Taking the Occupational Historydepts.washington.edu › uwmedres › pdf › clinics › Occupational_History.pdfmon illnesses (6). An example of the former may be a workei- in a foundry,

DIAGNOSIS AND TREATMENT

Taking the Occupational HistoryTHE OCCUPATIONAL AND ENVIRONMENTAL HEALTH COMMITTEE* OF THE AMERICAN LUNGASSOCIATION OF SAN DIEGO AND IMPERIAL COUNTIES; San Diego, California

The occupational history is an integral part of a thoroughmedical interview, but may be difficult to interpret. Aconvenient format for obtaining an individual occupationalhistory data base is provided, with guides to theinterpretation of pertinent responses. Once conipleted,the occupational history can be extended by selectedfollow-up questions and by consulting authoritativeinformation sources available to the clinician. Theoccupational history can be used on four levels: basic(a knowledge of the patient's current occupation andimplications of the present illness for employment),diagnostic (to investigate an association with the presentillness), screening (for individual surveillarice), andcomprehensive (to investigate complex problems indepth, usually in consultation with other occupationalhealth professionals). The format provided is suitable forthe screening level and to initiate investigation at thediagnostic and comprehensive levels.

T H E CONSCIENTIOUS clinician places great emphasis onthe patient's medical history. The well-known directionof Osier to "listen to the patient" is accepted withoutquestion by virtually all physicians. Yet many clinicianswho would never omit the family history from a thor-ough interview, or disregard the patient's current medica-tion in the evaluation of a new and unexplained rash, willignore or disregard that part of the patient's history deal-ing with one third of the patient's life. Often, mention ofthe patient's current occupation will be omitted entirelyfrom the medical record or will be confined to billinginformation (1).

The occupational history is an integral part of a thor-ough medical history, but its proper application requiresa fund of knowledge and training (1, 2). In this way, theoccupational history is no different from the family histo-ry or the past medical history. Without a working knowl-edge of occupational medicine, however, the occupation-al history is a bewildering catalogue of exposures to unfa-miliar chemicals and the physical or psychological stress-es of many jobs. The complexity of interpreting the occu-pational history is discouraging to many clinicians whomight otherwise incorporate it into their practice.

In 1978, the American Lung Association of San Diegoand Imperial Counties devised an occupational historyform that was extensively used in metropolitan San Die-go and elsewhere. In the second phase of this continuingproject, the Association's Committee on Occupationaland Environmental Health has adapted the form for con-

*Tee Lamont Guidotti, M.D., M.P.H., Chairman; Jan H. Cortez, B.S., Staff.Members of the Occupational History Subcommittee: Herrold L. Abraham,M.D.; William Hughson, M.D., Ph.D.; Abraham D. Krems, M.D., Ph.D.; Thom-as S. Neuman, M.D.; Andrew L. Bryson, M.S.; and Brian I. Heramb, B.S.

• From the American Lung Association of San Diego and Imperial Counties; SanDiego, California.

Annals of Internal Medicine. 1983;99:641-651.

venient insertion in the medical record. (This forrri isreproduced full size on pages 643-644 for convenience inxerographic copying.) We discuss here the purpose, for-niat, and use of the occupational history.

Reasons for Obtaining the Occupational History

A frequent objection to the occupational history is thatit is an impractical addition to an already extensive database on each patient and is unnecessary in the evaluationof most patients. However, when properly used, the occu-pational history need not be burdensome. Like every oth-er component of a thorough patient interview, it may beabbreviated, expanded, or specifically focused, but itshould never be omitted.

Although the performance of an occupational historyrequires some cost in time and effort, the benefits can beextraordinarily high. Such a payoff cannot be expected inevery case, of course, but over time the value of inquiryinto occupation becomes apparent as cases are identifiedin which a significant exposure, ergonomic problem, orsafety hazard would otherwise have been overlooked. Ifthe performance of virtually risk-free investigative procerdure is beneficial to many patients, the additional effort toimplement it merits the consideration of a conscientiousclinician.

Legal precedent is currently incomplete. However, theliability of the physician should be cause for concern if acorrectable occupational hazard is ignored or if a poten-tially compensable disability is inadequately evaluatedand falsely denied or falsely certified (3).

This is an era when health care financing is dominatedby employer payment of premiums for third-party cover-;age and workers' compensation. There is a distinct trendtoward contractual arrangements between health care fi-nancing agents and health care providers to provide carefor groups of patients. The adequacy of a provider's man-agement of occupational illness and injury will, likelyemerge as a factor to be considered in view of the uncon-trolled rise in costs to the employer of employee healthinsurance and workers' compensation assessments, aswell as collective bargaining agreements.

Although occupational medicine has recently receivedmuch more attention in the medical literature, it is not apassing interest. Rather, concern about occupational ill-nesses and injuries historically runs in cycles in the Unit-ed States; this concern reached a'irecent nadir in the1960s from which it is now regaining prominence. In Eu-rope, the appreciation of occupational associations of ill-ness and injury has been more consistent than in theUnited States (1).

© 1983 American College of Physicians 6 4 1

Four Levels of Use of the Occupational History

As in all medical data-gathering activities, the occupa-tional history must be used selectively (4, 5), A compre-hensive evaluation is simply not necessary for most pa-tients seen in a primary care setting. However, a generalawareness of the patient's occupation, or lack of employ-ment, is almost always desirable for the proper manage-ment of adults. Four levels of use of the occupationalhistory can be identified,

BASIC

This basic level is the one appropriate for most pri-mary care problems, in which the presenting illness isacute, presents no diagnostic dilemma, and is straightfor-ward to manage. The only essential datum is the patient'scurrent occupation or employment status (if unemployedor retired). The implications ofthe occupational historyare threefold: Is there a direct occupational associationthat may be overlooked that bears on the patient's condi-tion and alters management, such as a welder whose"simple" diagnosis of influenza may really be metal fumefever? Is there an occupational association that is reporta-ble, such as a simple back strain that the patient on ques-tioning recalls having occurred while on the job? Whatare the implications for the patient's return to work, suchas laryngitis that affects a teacher, who may have to delaya return to the classroom?

DIAGNOSTIC

A more complex medical problem may require a limit-ed series of questions designed to identify a specific occu-pational association, without necessarily reviewing thepatient's entire occupational history. An example is a pa-tient with an entrapment syndrome (usually carpal turi-nel) who on questioning is shown to have an ergonomicbasis for the condition, such as repetitive rotation at thewrist on an assembly line. Here, the same questions per-tain as in the basic level, but the occupational historyassists in the diagnosis and manipulation of the patient'sjob assignment or work practices. Examples of the latterinclude preventing a patient with an allergy from sustain-ing further exposure to the offending agent in the work-place, or teaching a patient with chronic low back painthe correct technique for lifting objects,

SCREENING

A more complete occupational history is needed whenaccumulating a data base for screening patients or groupsof patients. This may be in the context of surveillance, inwhich a patient at risk for a condition is followed forearly detection of that condition; or periodic healthscreening, in which persons in generally good health arefollowed for disease prevention or early detection of com-mon illnesses (6). An example of the former may be aworkei- in a foundry, smelter, battery plant, or drop-hani-mer operation who is at risk for lead intoxicatiori. Anexample of the latter may be the executive who, beforeentering management, put himself through college byworking summers on construction projects where asbes-tos was used. In this situation, the history should high-

light significant exposures, provide an adequate data baseto modify the screening procedure if necessary, and allowreconstruction of the most probable attribution of liabili-ty if the patient subsequently develops an occupationallyrelated condition. It should be noted that this documen-tation protects employers against liability for problemsthat were more plausibly associated with exposure onprevious jobs and assists the employee in making claiinsin the future by providing a less biased record of pastexposure. The occupational history form is designed to beused for this purpose.

COMPREHENSIVE

The most complete occupational history is appropriatefor the investigation of complex medical problems indepth. At this level, the history must be comprehensiveand detailed, and explore all reasonable alternative riskfactors. Such a comprehensive ievaluation is obviously im-practical for most situations and almost always requiresconsultation with specially-trained occupational healthprofessionals. Examples of difficult cases requiring thisapproach include interstitial pneunionitis, pneumocon-ioses, peripheral neuropathies, bladder cancer, leukemia,recurrent fever of unknown origin, and others involvingevery organ system. Occasionally, such investigationslead eventually to the identification of newly recognizedoccupational illnesses, as in the case of vinyl chloride-as-sociated hepatic angiosarcoma, dimethyl-aminoproprion-itrile-associated autonomic dysfunction, dibromochloro-propane-associated infertility, and silicosis-induced im-munosuppression resulting in acinetobacter pneumonia.Difficult cases such as these require an evaluation far be-yond the scope of the occupational history form providedhere, but the investigation may properly begin with thisinstrument.

Structure and Purpose of the Occupational History Form

The occupational history form is divided into threeparts. The occupational profile is an inventory of occupa-tional experience from which exposure to hazards andthe degree of risk can be reconstructed. The occupationalexposure inventory is a directed interview intended toidentify factors of susceptibility, to alert the clinician to ahistory of occupationally related disorders, and to con-firm and extend the history of hazardous exposures. Theenvironmental history is intended to alert the physicianto the possibility of home or avocational exposures,which are not strictly occupational but may produce asimilar outconie. All three parts are essential to the prop-er use of the occupational history form and must be re-viewed together for adequate evaluation. The form is de-signed for convenient self-administration; it can be com-pleted while the patient is waiting or mailed tp the patientbefore a scheduled appointment. Because it is self-admin-istered, the form can be used in situations where no suit-ably trained staff person is available to conduct an inter-view.

The occupational profile is a comprehensive inventoryof the patient's occupations, employers, and potential ex-posures. This part of the occupational history form is

5 4 2 November 1983 • Annals of Internal Medicine • Votume 99 • Number 5

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III. OCCUPATIONAL EXPOSURE INVENTORY

1. Please describe any health problems or injuries you have experienced connected with your present or past jobs:

2. Have any of your co-workers also experienced health problems or injuries connected with the same jobs? No YesIf yes, please describe:

3. Do you or have you ever smoked cigarettes, cigars, or pipes? No Yes

If so, which and how many per day:

4. Do you smoke while on the job, as a general rule? No Yes

5. Do you have any allergies or allergic conditions? No YesIf so, please describe:

6. Have you ever worked with any substance which caused you to break out in a rash? No YesIf so, please describe your reaction and name the substance:

7. Have you ever been off work for more than a day because of an illness or injury related to work? No YesIf so, please describe:

8. Have you ever worked at a job which caused you trouble breathing, such as cough, shortness of wind, wheezing? No YesIf so, please describe:

9. Have you ever changed jobs or work assignments because of any health problems or injuries? No YesIf so, please describe:

10. Do you frequently experience pain or discomfort in your lower back or have you been under a doctor's care for back No Yesproblems?If so, please describe:

11. Have you ever worked at a job or hobby in which you came into direct contact with any of the following substancesby breathing, touching, or direct exposure? If so, please check the box beside the substance.

D Acids D Beryllium D Chromates • Heat (severe) D Nickel D Radiation D TrichloroethyleneD Alcohols D Cadmium • Coal dust D Isocyanates D Noise (loud) D Rock dust D Trinitrotoluene

(industrial) D Carbon D Cold (severe) D Ketones D PBBs D Silica powder D VibrationD Alkalis tetrachloride D Dichlorobenzene D Lead D PCBs D Solvents D Vinyl chlorideD Ammonia D Chlorinated D Ethylene dibromide D Manganese D Perchlcroethylene D Styrene D Welding fumesD Arsenic naphathalenes D Ethylene dichloride D Mercury D Pesticides D Talc D X-raysD Asbestos D Chloroform D Fiberglass D Methylene D Phenol D TolueneD Benzene D Chloroprene D Halothane chloride D Phosgene D TDI or MDI

If you have answered "yes" to any of the above, please describe your exposure on a separate sheet of paper.

IV. ENVIRONMENTAL HISTORY

1. Have you ever changed your residence or home because of a health problem? No YesIf so, please descr ibe:

2. Do you live next door to or very near an industrial plant? No YesIf so, please descr ibe:

3. Do you have a hobby or craft which you do at home? No YesIf SO, please descr ibe:

4. Does your spouse or any other household member have contact with dusts or chemicals at work or dur ing leisure No Yesactivities?If so, please descr ibe:

5. Do you use pest ic ides around your home or garden? No YesIf so, please descr ibe:

6. Which of the following do you have in your home? (Please check those that app ly )

n Air conditioner D Air purifier D Humidifier D Gas stove D Electric stove D Fireplace D Central heating

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6 4 4 November 1983 • Annals of Internal Medicine • Volume 99 • Number 5

designed to serve three distinct functions. By identifyingspecific industries in which the patient was employed, theoccupational profile raises the interviewer's index of sus-picion regarding possible exposures associated with thoseindustries. By identifying the specific job duties done bythe patient, the occupational profile alerts the interviewerto specific potential hazards in the workplace to whichthe patient has been exposed. These hazards cannot bedetermined merely by listing a job title. A "fireman" canwork on a hook and ladder or on a train, and a "techni-cian" or a "mechanic" can have many different responsi-bilities in different workplaces. Likewise, a welder mayweld many different materials under very different condi-tions. Identification of the known health hazards associ-ated with each job provides a double-check and clarifica-tion of the occupational exposure inventory, greatly ex-tending the usefulness of this later section and identifyingthe probable time elapsed since the exposure took place.In many important ways, the occupational profile resem-bles a medical history.

If the occupational profile resembles the medical histo-ry of a new patient evaluation, the occupational exposureinventory most resembles the review of systems. In thissection the patient is prompted to recall specific expo-sures of medical significance, and is asked about a fewspecific symptoms of particular concern or usefulness.Because the occupational history form is meant to extendthe scope of the physician's evaluation rather than tostand alone, questions on smoking, allergies, and cardinalsymptoms have been kept brief and to a minimum on thepresumption that the physician will record the data ingreater detail elsewhere in the medical record. The pur-poses of the occupational exposure inventory are toprompt recall of exposure to specific agents and to morefully characterize the circumstances of exposure. In prac-tice, the occupational exposure inventory highlights andcompletes the occupational profile, emphasizing thosepast or present employment situations most likely to posea risk to health. Both parts of the occupational historyform are required to yield a valid interpretation. Seriousomissions may occur when only one part is used; togeth-er, the two parts reinforce one another and prompt amore accurate recall.

The environmental history is intended to identify cer-tain important exposures in the home that may be clini-cally significant. In our experience a detailed environ-mental history contributes to the evaluation of a complexclinical problem most frequently in five circumstances:clinical manifestations of atopy (usually asthma), hyper-sensitivity pneumonitis, disorders related to hobbies, dis-orders related to the spouse's or other resident's occupa-tion, and neighborhood environmental exposure. The oc-cupational history form is not intended to be a guide tothe evaluation of clinical allergy and must be kept man-ageably brief. Emphasis has been on screening questionsrather than a comprehensive inventory of possible expo-sures.

Using the Form to Collect a Data Base

The occupational history form is designed to be self-

administered to conserve valuable physician and stafftime. Occasionally, patients may wish to take the formhome to consult personal records such as income tax re-turns or union documents. This use may be helpful incircumstances where the patient cannot clearly recall anemployment episode or when the patient is unable tocommunicate and the record must be reconstructed byrelatives. Before scheduled medical examinations, it isconvenient to mail the form to the patient in advance.The form collects basic data needed to construct a pre-liminary profile of risk and some information on the com-monest occupationally-associated health outcomes (7,8). The form cannot be comprehensive for all possibleoccupational illnesses.

Once the data base is collected, it can be rapidlyscanned for key exposure situations. The two critical col-umns are located in the occupational profile section andare headed "Describe your job duties" and "Knownhealth hazards in workplace". These two columns arearranged on the form so that they are adjacent and visu-ally emphasized. Scanned together, the two columns alertthe physician to high-risk situations. When a combina-tion has a potential for hazardous exposure. Tables 1 and2 have the information needed to make a preliminaryinterpretation of both the hazard and the exposure situa-tion.

The job duties can be better interpreted with referenceto the type of industry. (Knowledge ofthe specific work-place is necessary in the event that inquiries must bemade or a claim for compensation documented.) The du-ration of employment and the degree of personal protec-tion are also essential in judging the opportunity for sig-nificant exposure to a hazard. In cases of cancer orchronic illness, the specific dates of employment are crit-ical in determining whether sufficient time has elapsed toaccount for a plausible latency period for the disease inquestion.

The occupational exposure inventory is arranged sothat a quick glance down the right hand column instantlyidentifies a positive response. Likewise, all multiple-choice alternatives are clustered for rapid scanning. Theinterpretations of positive responses in the occupationalexposure inventory are relatively straightforward. Inten-tional redundancy is part of the design of this section inorder to obtain significant responses that may be misseddue to misunderstanding the wording of a question orpoor recollection that may be prodded by phrasing theinquiry differently.

Tables 1 and 2 are designed to be used together to aidin interpreting the occupational history. The job descrip-tions catalogued in the occupational profile can be com-pared with those listed in Table 2. Major categories ofexposure associated with these occupations are also listedin the table. Tables 1 and 2 list exposures and occupa-tions selected for their frequency in the United States;neither list is intended to be comprehensive. In our expe-rience, patients completing this and similar forms aremost likely to remember and to record on the form un-usual health hazards associated with their workplace.However, patients often tend to forget or take for granted

Occupational Health Committee • The Occupational History 645

Table 1. Selected Potentially Hazardous Exposures

A. Aerosols, Vapors, GasesCarbon monoxideFormaldehydeHydrogen sulfideEthylene oxideNitrogen dioxideOzonePhosgeneSmokeSewer gasSulfur dioxideInert gasesWelding fumes

B. Biological InhalantsBacteriaFungiMoldsSpores

C. Corrosive SubstancesAcidsAlkalisAmmoniaChlorinePhenol

D. Dyes, StainsAniline dyesAzo dyesBenzidine

E. Inorganic Dusts, PowdersAsbestosBerylliumCoal dustFiberglassNickelSilicaTalc

F. Insecticides, HerbicidesCarbamatesHalogenated

hydrocarbonsOrganophosphatesPhenoxyherbicides

G. Electromagnetic RadiationRadioactive materialsUltravioletX-rayYellowcakeMicrowaves

H. Metals, Metal FumesAluminuniArsenicCadmiumChromiumCobaltIronLeadMercuryNickel

I. Organic DustCotton dustWood dustPoison oak

J. Petrochemicals,Asphalt and tarCreosoteCoal tarPBB (polybrominated

biphenyls) and PCB( polychlorinatedbiphenyls)

Petroleum distillatesK. Physical Agents

Heavy liftingNoiseThermal stressVibration

L. PlasticsVinyl chlorideEpoxy resinsAcrylonitrileStyreneMethyl ethyl ketone

peroxideM. Sensitizing Agents

Methane diisocyanate,toluene diisocyanate

NickelPlatinumProteolytic (detergent)

enzymesAliphatic amines

N. SolventsBenzeneCarbon disulfideCarbon tetrachlorideChloroformMethanolTrichloroethyleneXyleneGlycol ethers

(cellusolves)

exposures that are routine or obvious to them, despitetheir unfamiliarity to the interviewer. The entries madein the column "known health hazards" on the occupa-tional history should therefore never be presumed to be acomplete exposure inventory.

The occupatiorial exposure inventory corripletes theprofile of the patient's exposure to hazardous substances,identifies factors that may modify exposure, and flags car-dinal symptoms of common occupational health prob-lems. If an exposure or symptom is mentioned in thissection that is omitted on the occupational profile, thepatient should be asked when the exposure or symptomoccurred, and this information should be recorded, di-rectly on the form if possible.

Integration of the Occupational History with the ClinicalEvaluation

The data base generated by the occupational historyform is useless unless it is applied to the evaluation of thepatient (1, 4, 5, 9). This may be done in three ways.

When the pat;ient i? well, as in a preplacement or peri-odic examination, or presents with a disorder for whichno occupational association is plausible, the occupationalhistory may suggest a need for monitoring the patient.For example, a person may have been exposed to a car-cinogen, such as asbestos or vinyl chloride, or to a sub-stance that may produce a chronic condition, such aslead pr silica. Such persons may merit periodic evaluationfor early detection, and periodic screening is required bylaw in some circumstances as for asbestos- or lead-ex-posed workers. For this reason, the occupational historyform is appropriate for all patients of working age as ascreening tool.

When the patient presents with a chief complaint andfindings that are not diagnostic, the occupational historycan be used to narrow the differential diagnosis by rulingout certain exposures or to suggest a diagnosis. For ex-ample, a patient with dyspnea and honeycombing on achest roentgenogram may have one of various causes ofinterstitial fibrosis, arriong them sarcoidosis and idiopath-ic interstitial fibrosis. If the occupational history suggestsexposure to beryllium, the patient may have a diseasethat is compensable under workers' compensation, butthat may otherwise be misdiagnosed as sarcoidosis. An-

Table 2. Inventory of Occupations and Corresponding Major Haz-ardous Exposures

Occupation or Activity

Agriculture, farming, and pestcontrol

Automobile, aircraft manufacturingand repair

Bakers, food handlersBoiler operations and cleaningCeramics and masonryCarpentry, woodworking, and

lumber industryChemical industry and usersConstruction work, demolition, road

work, maintenance, and plasteringDry cleaning, and laundryElectric, electronicsFoundry workHealth care, laboratory work, and

dental workMachinery, grinding, and metal workMiningOil industry, petrochemicalPaper industryPlastic manufacturingPlumbing, pipefitting, and shipfittingPrinting, lithographySandblasting, spray paintingShipyard, dock work, and

transportationTextile industryWeldingX-ray occupations

Exposures*

A,B,F,K

A,C,E,H,K,MB,L,MA,C,E,KE,H

B,I,J,K,NA-N

C,D,E,K,J,NJ,M,NC,E,H,J,MA;C,E,H,K

A,B,C,D,E,G,K,L,M,NA,C,H,K,M,NA,E,G,KA,C,J,K,NE,NE,J,LA,C,E,H,KD,I,K,NA,E,H,K,N

A,C,E,H,J,K,NA,D,E,I,NA,E,H,MG

* See Table I for exposure categories.

6 4 6 November 1983 • Annals of Internal Medicine • Volume 99 • Number 5

Table 3. Additional Questions for the Evaluation of Occupational Associations to the Present Illness

Question Interpretation

Is your condition better or worse when you are off work fora few days or on vacation?

Is your condition better or worse when you return to workafter a weekend or vacation?

Does your condition get worse or better after you have beenback at work for several days or shifts?

Describe your workplace. (Please draw a diagram and indicateyour work station.)

What ventilation systems are used in your workspace? Do theyseem to work?

Does the protective equipment you are issued fit properly? Doyou receive instructions in its proper use? Do you ever fix ormake changes in the equipment to make it more comfortable?

Where do you eat, smoke, and take your breaks when you areon the job?

Where are your (your spouse or partner's) work clotheslaundered?

How often do you wash your hands at work, and how do youwash them?

What is your spouse or partner's occupation?

Have any of your fellow workers experienced similar conditions?

Do you recall a specific incident or accident that occurred on thejob? Were others also affected?

Are animals (pets, livestock, birds, or pests such as mice) presentin the vicinity of the workplace? Has there been a change intheir health, appearance or behavior?

Identify patterns suggesting either improvement or exacerbationon withdrawal from exposure.

Identify patterns suggesting return of condition on reexposure inthe workplace.

Identify patterns suggesting either tolerance or cumulative effectswith multiple exposure.

Evaluate proximity to exposure, protection available (ventilationor barriers), mobility within workplace, location of coworkerswho may also be affected.

Obtain general impression of adequacy of ventilation by airmovement and odors.

Consider possibility that protective equipment is not fullyeffective. In the case of respirators (masks), ask if they are "fit-tested" to comply with Occupational Safety and HealthAdministration regulations.

Identify opportunities for food- and cigarette-borne intake,adequacy of rest stations (isolation from heat, noise, fumes).

Identify possibility of passive exposure at home or prolonged skincontact.

Identify potential for contamination of hands or contact withsolvents or drying agents.

Identify potential for passive exposure (occupational history forpartner may be indicated).

Identifying others who may have been affected may lead toinquiries which clarify tlie individual patient's problem.Prevention-oriented interventions or requests for investigationby the state or federal Occupational Safety and HealthAdministration rnay be required.

Identify unusual or transient conditions which may have resultedin an exposure not reflected in the occupational history, suchas leaks, fires, or uncontrolled exothermic chemical reactions.

Animal (and especially animal wastes) may be a source ofinfectious or allergic hazards. Animals may also respond totoxic exposures which affect humans.

Other possibility is that the same person could have ahypersensitivity pneumonitis that would benefit from dif-ferent treatment and by avoiding future exposure.

When the patient presents with a known disorder forwhich an occupational association is suspect or plausible,on the other hand, the occupational history is used as atool for clinical evaluation. When the disorder is acute orrecurrent, the next step is to establish a relationship be-tween the present illness and the pattern of work prac-tices (4, 9). Further inquiry may be necessary to docu-ment a pattern of association with work or the possibilityof passive exposure. Table 3 provides questions that canbe used to follow-up on positive responses or to investi-gate other possibilities for exposure.

The integration of the occupational history with theclinical evaluation requires answers to three questions insequence. The first two can be answered from the occupa-tional history; the third may require consultation: Towhat occupational hazards might the patient have beenexposed (Tables 1, 2, and 3)? What factors inherent inthe patient may predispose to or modify the response toan occupational hazard (Table 4)? What effects are likelyto be seen with this exposure situation (Tables 5 and 6)?

Applications of the Completed Occupational History Form

The data base obtained and organized by the occupa-tional history can be used in many applications in medi-cal practices. The following are specific applications illus-

trated by examples drawn from our experience in SanDiego.

PATIENT EVALUATION

The occupational history can be used on the diagnostic(focused) or comprehensive levels to evaluate a patient'spresenting illness, as in recent cases of toluene-inducedperipheral neiiropathy and suspected polychlorinated bi-phenyl intoxication. Our form is used for the evaluationof both hospital inpatients and outpatients.

COMPENSABILITY

Establishing eligibility for Social Security disability,workers' compensation, "black lung" benefits, or localplans require knowledge of the worker's exposure to oc-cupational risks. In cases of chronic illness, such expo-sure may be very distant (mesothelioma associated withexposure to asbestos decades previously), legally "dis-tributive" (a laboratory technician with cancer exposedto high and low level chemical carcinogens, asbestos, andlow-level radiation), or cumulative (hearing loss after ex-posure to noise in several jobs over many years) (10, 11).

LIABILITY AND RISK CONTROL

Documentation of previous exposure or response to ahazard capable of producing a chronic disorder (such ascancer, neuropathies, chronic pulmonary diseases, or or-thopedic complications) protects the employer from as-

Occupational Health Committee • The Occupational History 6 4 7

Table 4. Factors That Modify Risk of Occupationally Related Illness

Modifying Factor Known or Probable Effect

GeneralAgeSexSmoking status

Current smokerSmoker at time of exposureSmoking during exposure

Family history

ExerciseConditioningAt time of exposure

Metabolic states

MedicalAtopy

AsthmaEczema

Chronic respiratory diseaseRespiratory insufficiencyBronchitis

Chronic cardiovascular diseaseCardiac insufficiencyCoronary artery disease

InfectionAcute viral illnessExposure to infectious agents

Immune deficiency statesHereditaryImmunosuppressive therapy

Renal diseaseRenal insufficiencyChronic renal disease

Neurologic conditionsDiminished mental capacityNeurological diseaseSeizure disorderImpaired perceptive ability (visual

or hearing impairment, anosmia)Dermatologic conditionsSubstance abuse

Hepatic insufficiency

Systemic conditionsMalnutrition (general)Vitamin deficiency (selective)Inborn errors of metabolismGenetic diseases

Mental status

Youth—latency for cancer; Elderly—more susceptible to toxicitySex differences exist for some toxicity states; reproductive effects

Confers additive risk in some situationsConfers synergistic risk in some situationsModifies toxic exposure in some situations, such as polymer fume feverHereditary conditions or predispositions may be exacerbated or triggered, such as cancer-

prone families

Fitness may reduce susceptibility in some situationsGenerally, increased susceptibilityActivity of certain enzyme systems involved in activation, detoxification, and adaptation

to toxic exposures may modify response although within range pf normalGenerally, any debilitatirig condition may enhance clinical susceptibilityTendency toward easy sensitizationIncreased bronchial reactivity

Diminished pulmonary reserveIncreased bronchial reactivity; exacerbated bronchial irritation

Increased susceptibilityAngina in some situations, such as carbon monoxide, methylene chloride

Increased susceptibility to bronchial irritation; possibly synergistic effectsCertain exposures may depress host defensesIncreased susceptibility to infections

Additive or synergistic effects may occur with exposure to nephrotoxic agentsIncreased susceptibility to toxic agents excreted via renal routeImmunodeficiency; increased susceptibility to toxic effects

May affect judgment and response to exposure situationToxic effects may be additive; increased clinical susceptibilityCertain toxic exposures may alter thresholdImpaired ability to avoid hazard

Skin rashes may increase dermal absorption; rnay condition responseConcomitant alcohol and drug abuse may have additive or synergistic effects in some

situationsIncreased susceptibility to toxic agents detoxified by liver; increased susceptibility to

hepatotoxic agent; reduced hepatic reserve

Increased susceptibility to toxic effectsDiminished host defenses against toxic effectsSelective susceptibility (depending on abnorrnality)Certain genetic diseases associated with increased susceptibility to mutagenic effectsStress may increase susceptibility to some toxic exposures. Stress, affective disorders,

iieuroses or psychoses may mask, mimic, or subtly modify the clinical presentation

suming unwarranted liability for health problems thatmay have resulted from exposures occurring before thepatient's current employment. Examples include an em-ployee of a medical technology manufacturer who pre-sented with a metastatic, very poorly differentiated carci-noma presumed to be hepatocellular; evaluation showedthat the least plausible latency period of the cancer wouldhave exceeded the length of employment at the firm, butthat the patient had been exposed previously to variouspotential hepatotoxins as an insurance inspector special-izing in chemical storage facilities in an underdevelopednation, and also carried the hepatitis B surface antigen.An ergonomic example is the documentation of an em-ployee's history of back problems before he or she was

648

employed as a maintenance worker in a local publicagency.

SCREENING

The occupational history can be used to modify thestrategy and battery of tests used for surveillance of em-ployee groups and for periodic health screening. In theformer, the occupational history can be used to establishan estimate of risk and the design of an appropriate pro-gram of medical surveillance for persons known to havebeen exposed to a hazard, as in the case of a recent stnallgroup of employees of a major utility who sustained ex-posure to polychlorinated biphenyls. In the latter, a peri-odic occupational history update is incorporated into a

November 1983 • Annals of Internal Medicine • Volume 99 • Number 5

Table 5. Non-Profit Services Providing Consultation on the Evaluation of Occupational Exposures and Illnesses

National ResourcesAmerican Conference of Governmental Industrial Hygienists (ACGIH).

National professional association of practicing industrial hygiene personnel in federal, state, and local agencies. Compilesguidelines and practical information for the evaluation and control of the industrial environment. Publications on occupation-al health and safety are available and technical information is provided (513-661-7881).

American Medical Association. Department of Environmental, Public and Occupational Health.Consultation services are provided on occupational and environmental health topics. Staff consists of specialists in occupational

medicine, industrial hygiene, and environmental health. Publications on subjects related to above areas are available (312-751-6528).

Cancer Information Service, National Cancer Institute.Provides twenty-four telephone service answering questions about cancer and related diseases including causes, diagnosis,

treatment and prevention (toll free number: 800-638-6694).Art Hazards Information Center (Center for Occupational Hazards, Inc.).

National clearinghouse for research and information on health hazards in the arts (212-227-6220).Clearinghouse for Occupational Safety and Health Information. National Institute for Occupational Safety and Health (NIOSH).

Provides literature searches from these in-house data bases: NIOSHTIC—Bibliographic information, CRF—Current ResearchFile, and RTECS—Registry of Toxic EflFects of Chemical Substances; and provides NIOSH publications and general informa-tion from library or other sources upon request. Information (513-684-8326); publications (513-684-4287)- chemical infor-mation (513-684-8328).

RCRA Superfund Industry Assistance Hotline. U.S. Environmental Protection Agency.RCRA is the acronym for the Federal Resource Conservation and Recovery Act (toll free number: 800-424-9346).

Toxicology Information Response Center. Oak Ridge National Laboratory (fee for service).Provides answers to questions regarding toxic compounds and processes. Conducts literaturp searches and compiles bibliogra-

phies. Handles inquiries from government agencies, physicians, lawyers, and private citizens (615-576-1743).U.S. Consumer Product Safety Commission.

Provides information on the safety of consumer products. Current subjects of study are kerosene heaters, formaldehyde,asbestos, and other indoor hazards. Fact sheets and booklets are available upon request (toll free number: 800-638-2772).

Regional ResourcesEducational Resource Centers

The National Institute for Occupational and Environmental Health (NIOSH) supports Educational Resource Centers at majorU.S. colleges and universities. These Centers provide continuing education and training to occupational health and safetyprofessionals. In addition, consultation is provided to physicians and health professionals by in-house occupational healthspecialists. Centers throughout the United States include:Region I (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont): Harvard School of Public Health,

Department of Environmental Health Sciences (617-732-1260).Region II (New Jersey, New York, Puerto Rico, Virgin Islands): Mount Sinai School of Medicine (212-650-6174).Region III (Delaware, District of Columbia, Maryland, Pennsylvania, Virginia, West Virginia): The Johns Hopkins Univer-

sity School of Hygiene and Public Health (301-955-3602).Region IV (Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee): University of

North Carolina School of Public Health, Department of Environmental Sciences and Engineering (919-962-2101); Univer-sity of Alabama at Birmingham, School of Public Health (205-934-7032).

Region V (Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin): University of Cincinnati, Institute of EnvironmentalHealth (513-872-5701); University of Illinois School of Public Health (312-996-7887); University of Minnesota School ofPublic Health (612-221-8770); University of Michigan, Department of Industrial Operations Engineering (313-763-2245).

Region VI (Arkansas, Louisiana, New Mexico, Oklahoma, Texas): The University of Texas Health Science Center atHouston, School of Public Health (713-792-7450).

Region VII (Iowa, Kansas, Missouri, Nebraska): No center in this region.Region VIII (Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming): Rocky Mountain Center for Occupation-

al and Environmental Health, University of Utah Medical Center (801-581-8719).Region IX (Arizona, California, Hawaii, Nevada): Arizona Center for Occupational Safety and Health, University of

Arizona Health Sciences Center (602-626-6835); University of California, Irvine, Department of Community and Envi-ronmental Medicine (714-752-2335); University of California at Berkeley (415-642-0761).

Region X (Alaska, Idaho, Oregon, Washington): Northwest Center for Occupational Safety and Health, University ofWashington, Department of Environmental Health (206-543-1069).

Local ResourcesComputer search services through local medical libraries, such as Medline and Toxline.County health departments; some have occupational health bureaus for county employees; environmental health bureaus may also

be helpful.Hospital, medical, or law libraries. Be certain references are current; law libraries often have extensive sections on occupational

health and forensic toxicology.Local American Lung Association affiliates; information and referral service, occupational health materials available.Nonprofit health research and education organizations, such as the Western Institute of Occupational and Environmental Sci-

ences, Berkeley, California.Occupational Safety and Health Administration (OSHA), local offices, or OSHA-approved state agencies. Consultation services

are available to answer public and professional inquiries in both federal and state OSHA offices, usually in major cities.Poison control centers.University programs in occupational health, industrial hygiene, or toxicology. Many universities have occupational health pro-

grams that are not educational resource centers but function as regional resources, such as University of Iowa School ofMedicine, University of Pittsburgh Graduate School of Public Health, San Diego State University Graduate School of PublicHealth.

Occupational Health Committee • The Occupational History 6 4 9

Table 6. Sources of Information for the Interpretation of the Oc-cupational Exposure Profile*

BECKER CE, ed. Occupational disease—New vistas for medi-cine. WestJMed. 1982;137:477-594.

BURGESS WA. Recognition of Health Hazards in Industry: Re-view of Materials and Processes. New York: John Wiley andSons, Inc.; 1981.

CLAYTON GD, CLAYTON FE, eds. Patty's Industrial Hygieneand Toxicology. 3rd ed. New York: John Wiley and Sons;1982.

DouLL J, KLAASEN C, AMDUR M , eds., Casarett and Doull'sToxicology. 2nd ed. New York: Macmillan; 1980.

FiNKEL AJ. Hamiton and Hardy's Industrial Toxicology. 4thed. Littleton MA: John Wright—PSG; 1982.

GLEASON MN, GossELiN RE, HODGE HC, SMITH RF. Clini-cal Toxicology of Commercial Products. Baltimore: Williamsand Wilkins Co.

GOODMAN LS, GILMAN AG. Goodman and Gilman's ThePharmacologic Basis of Therapeutics. 6th ed. New York:Macmillan; 1980.

HANENSON IB. Quick Reference to Clinical Toxicology. Phila-delphia: J.B. Lippincott; 1980.

KEY M M , HENSCHEL AF, BUTLER J, LIGO RN, TABERSHAWIR, EDE L. Occupational Diseases: A Guide to their Recog-nition. Washington, D.C: U.S. Department of Health, Edu-cation and Welfare, Public Health Service, Centers for Dis-ease Control, National Institute for Occupational Safety andHealth; 1977.

KusNETZ S, HUTCHISON MK, eds. A Guide to the Work-Re-latedness of Disease. Cincinnati, Ohio: U.S. Department ofHealth, Education and Welfare, Public Health Service, Cen-ters for Disease Control, National Institute for OccupationalSafety and Health; 1979.

LEVY BS, WEGMAN DH, eds. Occupational Health. Boston:Little, Brown and Co.; 1983.

MERCK, SHARP AND DOHME. Merck Manual of Diagnosis andTherapy. Rahway, New Jersey: Merck Sharp and DohmeResearch Laboratories.

MICHAELS D , MARKOWITZ S. Learning about Patients' Occu-pations: Why and How. New York: Department of SocialMedicine, Montefiore Hospital; 1980.

OLISHIFSKI JB, ed. Fundamentals of Industrial Hygiene. Chica-go: National Safety Council; 1979.

PROCTOR NH, HUGHES JP. Chemical Hazards of the Work-place. Philadelphia: J.B. Lippincott; 1978.

ROM WN, ed. Environmental and Occupational Medicine. Bos-ton: Little, Brown & Co.; 1983.

U.S. NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY ANDHEALTH, OCCUPATIONAL SAFETY AND HEALTH ADMINIS-TRATION. Occupational Health Guidelines for ChemicalHazards. Washington D.C: U.S. Government Printing Of-fice; 1981. DHHS (NIOSH) Publication No. 81-123. (can-not be used alone—guidelines for many common and impor-tant hazards are omitted because of federal standards review)

WARREN B, GRAY MR. The Occupational and EnvironmentalHistory: Project Module. Tucson, Arizona: Arizona Centerfor Occupational Safety and Health; 1980. (HRA ContractNo. 232-78-0191)

ZENZ C ed. Occupational Medicine: Principles and PracticalApplications. Chicago: Year Book Publishers; 1975.

ZENZ C, ed. Developments in Occupational Medicine. Chicago:Year Book Publishers; 1980.

* This list is not intended to be comprehensive. Only selected sources of infor-mation that are accessible and readily useful as a reference by the practicingclinician are included.

lifetime health monitoring program developed for the oc-cupational medicine service of a large medical grouppractice and routinely admihistered to employees of par-ticipating employers (6).

RESEARCH

Compilation of a data base on occupational exposuresis invaluable for epidemiologic research, both when theprimary interest is in occupational associations of diseaseand when occupational exposures may be a confoundingvariable or contributing risk factor. Adaptations of ourform have been incorporated into research projects by theGraduate School of Public Health at San Diego StateUniversity. An abbreviated occupational history shortlywill be administered to all patients admitted to the Can-cer Center at the University of California San DiegoMedical Center.

COMMUNITY EDUCATION

As a tool to increase public awareness of occupationalhazards, a simplified version of the occupational historycan be very effective. An earlier version of our form wasadministered to several dozen observers of an exhibit at aregional shopping center during a community health fairin a largely white-collar, upper middle-class neighbor-hood in San Diego. As the large number and diversity ofpotentially hazardous exposures occurring in the pastamong the unselected participants became obvious, theexercise served to show to the assembled crowd the ubi-quity of occupational hazards, even in a population con-sidered to be at low risk. Of course, such informal exer-cises have no epidemiologic significance and are not de-signed for any purpose other than to impress on the pub-lic that such hazards are not rare.

Summary

The occupational history is an integral component of athorough medical interview. Once acquired, however, thedata base must be interpreted. It is at this step that clini-cians may become discouraged in their efforts to improvetheir skills in evaluating the occupational associationsand implications of illnesses and injuries. We hope thatthis form and guide will assist the practitioner in makingfull use of the clinically pertinent information that can beobtained by the critical and selective use of the occupa-tional history.ACKNOWLEDGMENTS: The authors thank the following institutions forsharing their current work in progress: the Graduate School of PublicHealth at San Diego State University, The Rees-Stealy Medical Group (SanDiego), University of California San Diego School of Medicine, Universityof Arizona, Montefiore Hospital and Medical Center (New York), the Uni-versity of Washington, Miller Communications, Inc. (Norwalk, Connecti-cut), and the Atlantic Richfielti Company (Los Angeles). The authors alsothank Ruth M. Heifetz and Thomas V. McManamon for their work on theoriginal version of the occupational history format.

• Requests for reprints should be addressed to the American Lung Associa-tion of San Diego and Imperial Counties, 3861 Front Street, P.O. Box 3879;San Diego, CA 92103.

References1. FELTON JS. The occupational history: A neglected area in the clinical

history. 7Fam iVacf. 198O;ll:33-9.2. ROSENSTOCK L. Occupational medicine: too long neglected. Ann Intem

Med. 1981;95:774-6.3. ZASLOW J. Medical malpractice. In: LADOU J, ed. Occupational Health

Law: A Guide for Industry. New York: Marcel Dekker, Inc.; 1981;146-9.

4. GOLDMAN RH, PETERS JM. The occupational and environmentalhealth history. JAMA. 1981;246:2831-6.

5. WARREN B, GRAY MR. The Occupational and Environmental Health

650 November 1983 • Annals of Internal Medicine • Voiume 99 • Number 5

History: Project Module. Tucson: Arizona Center for OccupationalSafety and Health, 1980; HRA Contract No. 232-78-0191.

6. GUIDOTTI TL. Application of the lifetime health monitoring programconcept to defined populations not at exceptional risk. / Occupat Med.1983. (In press).

7. U.S. DEPARTMENT OF LABOR. An Interim Report to Congress on Oc-cupational Diseases. Washington D.C: U.S. Department of Labor, As-sistant Secretary for Policy, Evaluation and Research; 1980: 11-53.

8. DIVISION OF LABOR STATISTICS AND RESEARCH. California Work In-juries and Illnesses, 1980. San Francisco: California Department of In-

dustrial Relations; 1982.9. BECKER CE. Key elements of the occupational history for the general

physician. West J Med. 1982;137:581-2.10. MuLRYAN LE, MCCARTHY KJ, LADOU J. Cumulative injury and occu-

pational stress. In: LADOU J, ed. Occupational Health Law: A Guide forIndustry. New York: Marcel Dekker; 1981:73-87.

11. CALIFORNIA WORKERS' COMPENSATION INSTITUTE. Cumulative Inju-ry in Califomia: The Continuing Dilemma. San Francisco: CaliforniaWorkers' Compensation Institute; 1978.

Overdrive Pacing for Ventricular Tachyarrhythmias: A ReassessmentPETER R. KOWEY, M.D.; and TOBY R. ENGEL, M.D.; Philadelphia, Pennsylvatiia

Overdrive pacing was used for many years to preventventricular tachycardia and there are many reports of itseffectiveness. Nevertheless, the use of overdrive pacingfor most types of ventricular tachyarrhythmia has beenabandoned. One notable exception is torsades de pointes,in which interventions that increase heart rate, includingpacing, at least temporarily protect against recurrence.Overdrive may work by narrowing dispersion of ventricularrefractoriness, and measurement of the latter couldprovide a marker to selectively apply overdrive pacing,thus increasing its usefulness.

T H E RATIONALE FOR the use of overdrive pacing to pre-vent ventricular tachyarrhythmias is based on the obser-vation made early in this century that heart rate is criticalto the genesis of some arrhythmias. It was noted thatsevere bradycardia was frequently accompanied by com-plex ventricular ectopic activity. Syncope and suddendeath in patients with complete heart block often resultedfrom ventricular tachycardia or fibrillation. It was as-sumed that increasing heart rate would not only alleviatethe symptoms of bradycardia but also prevent the emer-gence of potentially lethal ventricular arrhythmias. Theliterature reporting the prevention of tachyarrhythmiasby pacing consists principally of many anecdotal case re-ports. Table 1 summarizes several studies in which morethan one representative case was reported.

The initial experience with overdrive pacing focused onpatients with atrioventricular block in an effort to main-tain heart rate to prevent recurrent ventricular tachycar-dia and fibrillation. Schnur (1) reported in 1948 that re-current ventricular tachycardia and fibrillation were pre-vented in a patient with complete heart block by usingepinephrine and ephedrine treatments to increase theventricular escape rate. ZoU and associates (2) in 1960reported their experience with external cardiac pacing forthe prevention of ventricular tachyarrhythmias after suc-cessful defibrillation. Four of their patients were main-tained in a regular rhythm for several hours to days, driv-ing the heart at a rate of 40 to 60 beats/min. Slowing theventricular paced rate to less than 40 beats/min resultedin ectopic activity that degenerated into ventricular fibril-

• From the Cardiovascular Division, Department of Medicine. The Medical Col-lege of Pennsylvania: Philadelphia. Pennsylvania.

lation. Their technique was painful, precluding continuedpacing, and many of these early patients eventually died.The next development was the use of electrodes affixeddirectly to the heart at thoracotomy, using an externalpower source, but the major breakthrough was implanta-tion ofthe power source. Dressier (3) reported his expe-rience with such a system in 1964. He noted that Adams-Stokes syndrome resulted from ventricular tachycardia in19 of 28 patients with the syndrome. Permanent ventricu-lar pacing at 60 to 80 beats/min prevented seizures in allofthe 19 patients, preventing further episodes of ventric-ular tachycardia in 15. Sowton and colleagues (4), in thesame year, reported 2 patients similarly benefiting fromchronic ventricular pacing. One of these patients neededboth drug therapy and a pacemaker, whereas the otherhad incessant episodes of ventricular fibrillation that werecontrolled for 14 days by ventricular pacing.

Ventricular pacing of patients in sinus rhythm for sup-pression of ventricular tachyarrhythmias (overdrive pac-ing) was pioneered by Eraklis and colleagues (5) and byHeiman and Helwig (6) in the mid-1960s. Eraklis andcolleagues (5) reported the case of a patient temporarilyresponding to atrial overdrive pacing during a stormypostoperative course after mitral commissurotomy. Hei-man and Helwig (6) treated two patients with overdrive.The first was a 42-year-old woman who, in retrospect,was considered to have torsades de pointes secondary toquinidine sulfate. Her torsades was resistant to all antiar-rhythmic agents but responded to atrial pacing at 155beats/min. Over the next week, the pacing rate was pro- •gressively lowered to 110 beats/min, but rechallenge withquinidine caused recurrence of torsades. The patient wasweaned from the pacer after the quinidine was stopped,but she died 3 months later. Their second patient had asimilar syndrome and needed permanent ventricular pac-ing (110 to 130 beats/min). This patient had a function-ing pacemaker at the time of discharge but died suddenly6 months later.

Kastor and coworkers (7) reported the successful useof temporary pacing to treat ventricular tachyarrhythmi-as in two patients, one of whom required pacing at 100beats/min. Both patients needed only temporary pacingand were well at discharge. Wellens and associates (8)

Annals of Internal Medicine. 1983;99:651-656. © 1983 American College of Physicians 6 5 1