Prevalence of Latent TB among Health Care Workers in Four Major Tertiary Care Hospitals in Riyadh, Saudi Arabia

THE JOURNAL OFTHE EGYPTIAN PUBLICHEALTH ASSOCIATION

Vol. 85 No. 1&2 2010

J Egypt Public Health Assoc Vo/. 85 N°. 1 & 2,2010

Prevalence of Latent TB among Health CareWorkers in Four Major Tertiary Care Hospitals

in Riyadh, Saudi Arabia

Moustafa A.F. Abbas *'**, Nasser AE. AIHamdan *, Lamiaa A.Fiala **,*** Awwad K. AIEnezy ****, Mohamed S. AIQahtani ****

* Community Medicine Dept., Faculty oJ Medicine, KFMC, KSA U-HS,Riyadh, Saudi Arabia

** Community Medicine Dept., Faculty oJ Medicine, Suez Canal University,Ismailia, Egypt

*** Community Health Sciences Dept., King Saud University, Riyadh, SaudiArabia

****Employee Health Clinics, KFMC, MOH, Riyadh, Saudi Arabia

ABSTRACT

Background: Tuberculosis (TB) infection represents a global health

problem and a great risk to Health Ca~'e Workers (HCWs). Identifyingindividuals, particularly HCWs with latent tuberculosis infection (LTBI)will support TB control through chemoprophylaxis and prevent crossinfection. Objectives: This study aimed to identify prevalence of Latent

TB among a two-year new hires of HCWs in 4 major tertiary carehospitals in Riyadh, Saudi Arabia. Material and Methods: 2650 recently(2-years) hired HCWs were surveyed for latent TB using TuberculinSkin Test (TST). Data was collected from January 2008 to December

2009. Induration due to TST equal to or more than 10 mm. within 48-72hours was considered positive. The results of TST were correlated withother variables such as age group, gender, job category, country of

origin. Results: as an overall rate, 291(11%) out of 2650 were positive forTST, with the highest significant positive rates among physicians(14.9%) and nurses (12.9%) compared to students as a reference group.

Corresponding Author:Dr. Moustafa A. F. Abbas

Community Medicine Dept.Faculty of Medicine, King Fahad Medical CityRiyadh, Saudi Arabia.Faculty of Medicine, Suez Canal University.Ismailia, Egypt.Email: [email protected]

J Egypt Public Health Assoc Vol. 85 N°. 1 & 2,2010

No statistically significant difference was detected between both sexes.The highest significant positive TST rates were found among HCWs inthe age group of 50 years and older (32.6%) compared to 10-19years agegroup as a reference group, and among HCWs coming from subSaharan countries (61.1%) compared to Saudi HCWs with the lowestpositive rates (5%) as a reference group. Conclusion andrecommendations: LTB is prevalent among newly hired HCWs inRiyadh tertiary hospitals. Stcndard programs for detection andtreatment of LTBshould be encouraged.

Keywords: Health Care Workers (HCWs), Latent Tuberculosis (LTB),occupational health.

INTRODUCTION

Tuberculosis is a global health problem and World Health

Organization (WHO) in 2010 reported that someone in the world

is newly infected with TB bacilli every second. One-third of the

world's population is currently infected with the TB bacillus.

Also, 5-10% of people who are infected with TB bacilli (but whoare not infected with HIV) become sick or infectious at some time

during their life.(l)

TB is on the list of biologic health hazards to HCWs, and

remains a very important occupational risk for HCWs in Low andMedium Income Countries and for workers in some institutions

in High Income Countries. Risk appears particularly high whenthere is increased exposure like working at infectious diseases

hospitals, emergency rooms and laboratory settings, combined

with inadequate infection control measures.(2-4)

De Vries et aI., (2006) (5) confirmed the importance of

vigilance in TB control and emphasized that a high suspicion of

tuberculosis by the clinician, adequate infection control

78


measures by hospital authorities, and early identification of

latent tuberculosis infection by occupational and public-healthspecialists are necessary to prevent tuberculosis amonghealthcare workers.

Many studies pointed to the high prevalence of Latent TB

among health care workers that reached up to 69% in some

studies. (6,7) On the other hand, molecular-epidemiologicalstudies and a comprehensive review of the existing evidence

concerning the infection risk for HCWs lead to the conclusion

that TB in HCWs is often caused by infection at the workplace. (8)

TST testing has been accepted universally as the main

method for detecting LTB, in spite of its limitations and theeffectiveness of recent BCG vaccinations. (9,10)

Identifying positive Latent TB among HCWs helps m

reducing the risk of later development of open TB among them.

The aim of this study was the identification of the prevalence of

Latent TB among recently hired HCWs in 4 major tertiary carehospitals in Riyadh, Saudi Arabia.

MATERIAL AND METHODS

This study included 2650 recently hired HCWs in 4 major

tertiary care hospitals in Riyadh, Saudi Arabia, starting from

January 2008 to December 2009. Data were collected from eachHCW including; age, gender, job category, and country of

citizenship. They were examined for Latent TB using TST byinjection of 0.1 ml (5 units) of Purified Protein Derivative (PPD)

intracutaneously, usually in the volar aspect of the forearm. Thereaction was read 48-72 hours later, the size of the reaction was

determined by measurement of the induration not the erythema.

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A measurement equal to or more than 10 mm was considered

positive. (11- 13) The results of the TST testing were correlated withother variables.

Statistical analysis:Statistical analysis was done using the Epi Info Software

program, version 6.04 (14) and the SPSS program version 16. (15)

Odds ratios were calculated and p values less than 0.05 were

considered significant.

RESULTS

Table (1) shows that the 2650 HCWs who participated in the

study included 429 (16.2%) physicians, 1164 (44%) nurses, 423

(16%) technicians, 453 (17.1%) administrative employees and

181 (6.7 %) medical students. Out of the 2650 HCWs, 291 (11%)

were positive for TST, of them 64 (14.9%) were physicians, 150

(12.9%) were nurses, 41 (9.7%) were technicians, 32(7.1%) were

administrative employees and 4 (2.2%) were medical students.There were statistically significant differences between rates of

positive TST among different job categories of HCWs compared tostudents as a reference group. The highest odds of infection was

among physicians (7.76, 95%CI (2.66-25.46)).

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1Egypt Public Health Assoc

Table (1): TST Results According to Job Categories

Vol. 85 N°. 1 & 2,2010

TST Results

Job

PositiveNegativeTotal p value

No.

No.No.Odds Ratio ±95% Cl(%)

(%)(%)

64365

4290.0000**Physician 14.985.1

16.2OR=7.76; 95%CI(2.66-25.46)

150

101411640.0000**Nurse 12.9

87.144.0OR=6.55; 95%CI(2.31-21.01)

41

3824230.002**Technician 9.7

90.316.0OR=4.75; 95%CI(1.6-15.86)32

4214530.028*Administrative 7.1

92.917.1OR=3.36; 95%CI(1.l-11.38)

4

177181Student Reference group2.2

97.86.7

291

23592650Total 11.0

89.0100.0

* Significant p <0.05** Significant p <0.0 I

Table (2) shows that out of 1470 females, 170 (11.6%) wereTST positive, while out of 1180 males, 121 (10.3%) were positive.

However, this difference was not statistically significant

(p=0.284; OR=1.14, 95%CI=0.89-1.48). On comparing TST

results among different age groups with the results of the group

10-19 years as a reference group, there was no statisticaldifference between the age group 20-29 years and the referencegroup while, significant statistical differences were found with

the other age groups, with the highest statistical difference

among age group 50 years and older (p<O.OOOO;OR=19.12, 95%CI=6.63-59.30).

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J Egypt Public Health Assoc

Table (2): TST Rcsults according to Age group and Sex

Vo!. 85 N°. 1 & 2,2010

TST ResultsTotalVariable

PositiveNegativeNo.

p value

No.

No.(%)Odds Ratio ±95% Cl

(%)

(%)

Age (years) 5

19820310-19 2.5

97.5100.0Reference group

85

134014250.0620-29 6.0

94.0100.0OR=2.51; 95%CI (0.97-7.11)

112

6047160.00000*'30-39 15.6

84.4100.0OR=7.34; 95%CI (2.84-20.69)

61

1592200.00000**40-49 27.7

72.3100.0OR=15.19; 95%CI (5.69-44.02)

28

58860.00000**50+ 32.6

67.4]00.0OR=] 9.12; 95%C] (6.63-59.30)

Sex: 170

130014700.28Females 11.6

88.4100.0OR=1.14; 95%CI (0.89-1.48)

121

10591180Males 10.3

89.7100.0Reference group

291

23592650Total 11.0

89.0100.0

** Significant p <0.01

Table (3) shows that Saudi HCWs had the lowest TST

positive rates; 63(5%) out of 1254 HCWs. On comparing theresults of HCWs with other nationalities with the results of Saudi

HCWs as a reference group, there were statistical significant

differences between these nationalities and the reference group

with the highest significant difference among HCWs coming from

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sub-Saharan countries (p<O.OOl; OR=29.71; 95% CI=13.77

64.65).

Table (3): TST Results according to Nationality groups

TST ResultTotalp valueNationalityPositive

NegativeNo.No.

No.(%)Odds Ratio ±95% Cl

(%)

(%)

63

11911254Saudi

Reference group5.0

95.0100.0

0.00000**42

243285

Middle East

OR=3.27;95%CI(2.12-14.7

85.3100.05.04)

147

8349810.00000**East Asia 15.0

85.0100.0OR=3.33; 95%CI(2.42-4.59)

17

74910.00000**Western 18.7

81.3100.0OR=4.34; 95%CI(2.32-8.06)

22

14360.00000**Sub-Saharan 61.1

38.9100.0OR=29.71; 95%CI(13.77-64.65)

291

23562647Total 11.0

89.0100.0

**Significant p <0.01

DISCUSSION

Efforts to control Tuberculosis are huge but still inefficient.

One important step in TB control is to identify LTBI especiallyamong HCWs. In this study the prevalence of positive TST among

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J Egypt Public Health Assoc Vo/. 85 N°. 1 & 2,2010

HCWs was found to be 11% with the highest prevalence (32.6%)alIlOng age group 50 years or older. These results were

comparable to the findings of Nienhaus et al., (2007) (6) whofound a positive TST prevalence of 12.8%. In their study, therewas also strong relationship between age and TST results, with

the highest prevalence of positive TST (69.2%) among age group

60 years or more. On the other hand, lower rates were reportedby other studies. For example, among health care workers in a

hospital for pulmonary diseases in Germany, Schablon et al.,(2009) (7) found the prevalence of LTBI to be 7.2%. In HCWs

younger than 30 years LTBI prevalence was 3.5% and in thoseolder than 50 years it was found to be 22% which is less than

our findings probably due to the use of Quantiferon blood ELISA

testing which has much less false positive results than standardTST used in our study.

By using the interferon-gamma release assay (IGRA) inanother study by Nienhaus, (2009) (8) LTBI prevalence in HCWs

was 10 %, and this study recommended that preventionstrategies in Germany should be reconsidered.

On studying 1755 Italian HCWs, Franchi et al., in 2009 (9)

found the overall Positive TST to be 6% which is much less than

our findings, but agreed with our results in that older age andbeing physicians were high risk factors for TST positivity.

While Demkow et al., (2008) (16) on studying 155 HCWs m

Poland, using interferon-gamma whole blood and tuberculin skin

tests, found that the prevalence of LTBI was, on average, 27.1%,a higher risk of acquiring LTBI was associated with certain work

locations (TB lab workers--prevalence 50%, TB ward clinicians-

34%, nurses--30%, analytical lab technician-- 20%, and in

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J Egypt Public Health Assoc Vo!. 85 N°. 1 & 2,2010

administration staff-- 15%). Drobniewski et al., (2007) (17)

mentioned that Russia is one of 22 high burden tuberculosis

countries. LTBI was seen in 40.8% (107/262) of staff and was

significantly higher in doctors and nurses (39.1%) than in

students (8.7%). In their systematic review, Joshi et aI., (2006) (18)

reported high rates of LTB among HCWs in many countries; our

findings agreed with their results in that physicians had higherTST positive rates among all HCWs job categories.

CONCLUSIONS AND RECOMMENDATIONS

LTB was prevalent among HCWs (11%) who are newly hired

m major hospitals in Saudi Arabia. Higher TST positive rates

were associated with older age and certain job categories as

physicians and nurses. Testing of HCWs at hire and periodicallycan help in the detection of LTBI and using prophylaxistreatment for positive TST cases can reduce the number of HCWs

who may develop TB later on. There is a need for using the newly

introduced method of ELISA techniques in performing more

studies for detection of LTB, hopefully to increase true positive

results and reducing false negative results encountered on usingTST.

REFERENCES

1. World Health Organization. Tuberculosis. Fact sheet N°104, March,2010.

2. Menzies D, Joshi R, Pai M. Risk of tuberculosis infection and disease

associated with work in health care settings. Int J Tuberc Lung Dis.2007; 11(6):593-605.

85

J Egypt Public Helllth Assoc Vo!. 85 N°. 1 & 2,2010

3. Garber E, San Gabriel P, Lambert L, Saiman 1. A survey of latent

tuberculosis infection among laboratory healthcare workers in New

York City. Infect Control Hosp Epidemiol.2003; 24(11):801-6.

4. Driver CRI Stricof RL, Granville K, Munsiff SS, Savranskaya G,

Kearns C et al. Tuberculosis in health care workers during declining

tuberculosis incidence in New York State. Am J Infect Control. 2005;

33(9):519-26.

5. De Vries G, Sebek MM, Lambregts-van Weezenbeek CS. Healthcare

workers with tuberculosis infected during work. Eur Respir J. 2006;

28(6):1216-21.

6. Nienhaus A Schablon A Loddenkemper K Hauer B, Wolf N, DielR. Prevalence of latent tuberculosis infection in healthcare workers

in geriatric care. Pneumologie. 2007; 61(9):613-6.

7. Schablon A Beckmann G, Harling M, Diel R, Nienhaus A.

Prevalence of latent tuberculosis infection among health care

workers in a hospital for pulmonary diseases. Journal of

Occupational Medicine and Toxicology. 2009. [cited 2009 January

9]. Available from: http://www.occup-med.com/content/ 4/1/1

8. Nienhaus A. Tuberculosis in healthcare workers. Pneumologie.

2009; 63(1):23-30.

9. Franchi A, Diana 0, Franco G. Job-related risk of latent tuberculosis

infection in a homogeneous population of hospital workers in a low

incidence area. Am J Ind Med. 2009; 52(4):297-303.

10. Brodie D, Schluger NW. The diagnosis of Tuberculosis. Clin Chest

Med. 2005; 26: 247-71.

11. Centers for Diseases Control (CDC). Notice to readers: revised

technical instructions for tuberculosis screening and treatment for

panel physicians. MMWR. 2008; 57:292-3.

86


12. American Thoracic Society. Diagnostic standards and classification

of tuberculosis in adults and children. Am J Respir Crit Care Med.2000; 161: 1376-95.

13. Jasmer RM, Nahid P, Hopewell Pc. Latent tuberculosis infection. N

Engl J Med. 2002; 347(23): 1860-6.

14. Epi Info ver 6.04: Centers for Diseases Control, USA, Statistical

Package for Epidemiologists. Release 6.04, Augustl, 2001.

15. SPSS Ver 16: Statistical Package for Social Studies. SPSS Inc. USA,

Release 16.0.0, September 17, 2007.

16. Demkow U, Broniarek-Samson B, Filewska M, Lewandowska K,

Maciejewski J, Zycinska K, et (11. Prevalence of latent tuberculosis

infection in health care workers in Poland assessed by interferon

gamma whole blood and tuberculin skin tests. J Physiol Pharmacol;

2008; 59(6): 209-17.

17. Drobniewski F, Balabanova Y, Zakamova E, Nikolayevskyy V,Fedorin 1. Rates of latent tuberculosis in health care staff in Russia.

PLoS Med., 2007; 4(2): e55.

18. Joshi R, Reingold AL, Menzies D, Pai M. Tuberculosis among health

care workers in low- and middle-income countries: a systematic

review. PLoS Med. 2006; 3 (12):e494.

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Prevalence of Latent TB among Health Care Workers in Four Major Tertiary Care Hospitals in Riyadh, Saudi Arabia

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