Dupuytren’s contracture due to hand-transmitted vibration

Dupuytren’s contracture due to hand-transmitted vibration - CM8860 May 2014Dupuytren’s contracture due to hand-transmitted
vibration Report by the Industrial Injuries Advisory Council in accordance with Section 171 of the Social Security Administration Act 1992 considering prescription
for Dupuytren’s contracture in workers exposed to hand-transmitted vibration.
Presented to Parliament by the Secretary of State for Work and Pensions By Command of Her Majesty
May 2014
Cm 8860
Dupuytren’s contracture due to hand-transmitted
vibration Report by the Industrial Injuries Advisory Council in accordance with Section 171 of the Social Security Administration Act 1992 considering prescription
for Dupuytren’s contracture in workers exposed to hand-transmitted vibration.
Presented to Parliament by the Secretary of State for Work and Pensions By Command of Her Majesty
May 2014
Cm 8860
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ID 2642422 05/14
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INDUSTRIAL INJURIES ADVISORY COUNCIL
Professor K T PALMER, MA, MSc, DM, FFOM, FRCP, MRCGP (Chair)
Dr P BAKER, MA, DM, MB, BS, MFOM
Mr K CORKAN, BA
Mr R EXELL, OBE
Professor S KHAN, BMedSci, FFOM, FRCGP, FRCP, DM
Dr I MADAN, MB, BS (Hons), MD, FRCP, FFOM
Professor D McELVENNY, BSc, MSc, CStat, CSci
Professor N PEARCE, BSc, DipSci, DipORS, PhD, DSc, FMedSci
Professor A SEATON, CBE, MD, DSc, FRCP, FRCPE, FMedSci
Ms C SULLIVAN
Mr F M WHITTY, BA
Ex-Council members:
Professor Sir M AYLWARD, CB, MD, FRCP, FFPM, FFOM, DDAM
Professor M G BRITTON, MD, MSc, FRCP, Dip(Ind. Health)
Professor R GRIGGS, BA, PhD, OBE
Professor D KLOSS, MBE, LLB, LLM, Hon FFOM
Dr I J LAWSON, MB BS, DRCOG, CMIOSH, FFOM, FACOEM, FRCP
Mr S LEVENE, MA
IIAC Secretariat:
Mr G ROACH (retired)
Assistant Administrative Secretary Mrs Z HAJEE
Dear Secretary of State
Review of Dupuytren’s contracture and hand-transmitted vibration
We present our review of Dupuytren’s disease and work involving hand-transmitted exposure to vibration.
Dupuytren’s disease is a disorder of the hand in which thickening of fibrous tissue of the palm and finger tendons leads, in more advanced cases, to the digits becoming permanently bent (flexed) into the palm, this last state being called “Dupuytren’s contracture”. Our review has been triggered by correspondence from an MP requesting that the Council consider prescription for this condition.
Appraisal of the scientific research literature, new analyses of data held by experts in the field, and a call for evidence have led us to conclude that, given sufficient exposure to hand-held vibrating tools, risks of Dupuytren’s disease and contracture can be more than doubled (the normal threshold employed by the Council when recommending prescription).
Early (pre-contracture) stages of the disease are not significantly disabling, however, and would be unlikely to qualify for benefit. For this reason we recommend that only the contracture stage of disease, namely that involving fixed flexion deformity of one or more of the digits as defined in this report, be added to the list of prescribed diseases for which Industrial Injuries Disablement Benefit (IIDB) is payable. The report outlines a ‘table top’ test, which can be used as a simple screen to help identify disease of this severity. Qualifying exposures would be those arising from work for ten years or more in aggregate which involves the use of hand-held powered tools whose internal parts vibrate so as to transmit vibration to the hand for at least two hours per day on three or more days per week.
Yours sincerely
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Summary 1. This report reviews the link between work with hand-held vibratory tools and a
disorder of the hand called Dupuytren’s disease, in which thickening of fibrous tissue in the palm and tendons of the fingers leads, in more advanced cases, to the digits becoming permanently bent (Dupuytren’s contracture).
2. This condition has various established non-occupational causes. Additionally, associations have long been suspected with occupational use of hand-held powered vibratory tools, and evidence on this has grown over time.
3. The Industrial Injuries Advisory Council’s (IIAC’s) inquiries in this area have included a detailed review of the research literature, consultation with experts in the field, and fresh analyses of three existing datasets held by other parties. When taken together, the evidence indicates that risks of the disease can be more than doubled (the threshold commonly employed in deciding on prescription under the IIDB Scheme), provided that exposures to vibration are sufficiently long.
4. The Council recommends that Dupuytren’s contracture be added to the list of prescribed diseases for which IIDB is payable following work for ten or more years in aggregate which involves use of hand-held powered tools whose internal parts vibrate so as to transmit vibration to the hand for at least two hours per day on three or more days per week.
5. Dupuytren’s disease exists across a wide spectrum of severity, but the majority of cases cause little or no functional loss. To encourage claims activity only in circumstances where the assessed level of disablement is likely to contribute meaningfully to the award of benefit, the Council proposes that cases affecting only the palm and with no involvement of the fingers should be excluded from consideration; for the purposes of prescription, the disease should involve fixed flexion deformity (contracture) of one or more of the digits. The report outlines a ‘table top’ test, which can be used in clinical practice as an aid to define disease of this severity.
This report contains some technical terms, the meanings of which are explained in a concluding glossary.
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Background to the review 6. In January 2011, a Member of Parliament (MP) asked the Industrial Injuries Advisory
Council (IIAC) to consider prescription for Dupuytren’s contracture (Dupuytren’s disease) in relation to coal mining. This request triggered the present report.
7. Dupuytren’s contracture is a connective tissue disorder of the hand and fingers, in which the fingers of the hand become bent (flexed) into the palm so that they cannot be straightened (Figure 1). The ring finger and little finger are most commonly affected, and less often the middle finger and the index finger, with the thumb nearly always spared. The condition bears the name of Baron Guillaume Dupuytren, who first described it in 1831.
Figure 1 Hand with Dupuytren’s disease.
8. Slowly and painlessly over time, the fibrous tissue in the palm (palmar fascia) thickens. Typically, nodular thickenings, skin puckering and then fibrous bands become manifest in the palm. Eventually the connected digital tendons shorten and cannot move freely. The associated disablement arises because the affected digits have reduced function and grip may be impaired. The deformity may also cause distress, although, not infrequently, people accept it.
[Reprinted with permission from Professor Keith Palmer, Medical Research Council Lifecourse Epidemiology Unit, University of Southampton].
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Background to the review 6. In January 2011, a Member of Parliament (MP) asked the Industrial Injuries
Advisory Council (IIAC) to consider prescription for Dupuytren’s contracture
(Dupuytren’s disease) in relation to coal mining. This request triggered the
present report.
7. Dupuytren’s contracture is a connective tissue disorder of the hand and fingers,
in which the fingers of the hand become bent (flexed) into the palm so that they
cannot be straightened (Figure 1). The ring finger and little finger are most
commonly affected, and less often the middle finger and the index finger, with
the thumb nearly always spared. The condition bears the name of Baron
Guillaume Dupuytren, who first described it in 1831.
Figure 1. Hand with Dupuytren’s disease. [Reprinted with permission from Professor Keith
Palmer, Medical Research Council Lifecourse Epidemiology Unit, University of
Southampton].
8. Slowly and painlessly over time, the fibrous tissue in the palm (palmar fascia)
Nodule
Bands
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9. In severe cases the mainstay of treatment is surgical correction, which is effective, but is frequently followed by recurrence. Other modalities of treatment exist, a recent option involves the injection of an enzyme designed to weaken and dissolve the fibrous contractures.
10. A rough guide to severity is provided by the so-called ‘table top’ test – that is, the inability of a patient to place their hand flat against a hard surface, such as a table, because of fixed digital deformity. The disease can be staged clinically according to the presence of nodules, bands and degree of contracture. Although practices vary somewhat, many authorities suggest that surgery should be considered when:
(a) the metacarpophalangeal joint (the joint intersecting with the palm at the base of the finger) is bent forwards by 30 to 45 degrees and cannot be straightened; or
(b) the proximal interphalangeal joint (the second joint from the finger tip) is bent permanently by 10 to 20 degrees. Intervention at this point is recommended to promote a good surgical outcome.
11. Dupuytren’s contracture is a fairly common disorder amongst the general population, although estimates of frequency vary greatly depending on the age profile, clinical characteristics, nationality of surveyed samples and the criteria employed in case definition. The condition is comparatively rare before age 40 and becomes more common with age. Cases can run in families and are more common in certain countries (for example, Norway, Iceland, Scotland) than in others (for example, Japan), suggesting a genetic contribution to disease occurrence. Other recognised associations include diabetes, epilepsy (especially treatment with the antieplieptic drug phenytoin), heavy alcohol consumption and cirrhosis of the liver. Often, however, none of these risk factors are present.
12. Several estimates of disease frequency have been made in the UK. In 1951, Herzog examined the hands of 3,000 steel workers, miners, and office clerks from Northern England and estimated that 2 per cent had Dupuytren’s disease of any extent. In men over 40 years of age the prevalence rose to 4.3 per cent.
13. In 1962, Early surveyed 4,688 employees of a large engineering works, together with a cross-section of the population in Leigh, Lancashire and residents of a care of the elderly home. Some 3.8 per cent of men and 2.3 per cent of women were affected. Rates were higher at older ages. Thus, 7.4 per cent of men from the locomotive works aged 45 to 74 years had Dupuytren’s disease. In almost 80 per cent of cases, however, involvement was confined to the palm, without associated digital contracture.
14. Early’s findings imply that cases of the disease are often mild. Similarly, Mackenney (1983) in reporting a prevalence of 5 per cent among men and 3.5 per cent in women, chosen at random from 919 adults attending orthopaedic clinics in the Cotswolds and Chilterns, noted that the disease was confined to the palms in 58 per cent of assessed cases. Two other surveys imply that the disease is under-recorded in general practice records, probably because medical help is not always sought. Geoghegan et al. (2004) identified only 821 cases in a computerised database of more than 300,000 patients aged 20 years or more (less than 0.3 per cent), while Khan et al. (2004) reported a new consultation rate in general practice of only 0.034 per cent per year in a survey covering 500,000 patients.
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15. Finally, according to Lennox et al. (1993), in consecutive patients aged over 60 years from hospitals in Aberdeen, finger contracture was less common than palmar nodules in isolation (diagnosed orthopaedically in 35 of 400 assessed hands).
16. The available research suggests two broad links with occupational activity – with manual work and with exposure to hand-transmitted vibration (possibly, but not clearly consequent on the manual aspects of handling powered vibratory tools). A link with occupation was first suggested in the context of hand injury, although some uncertainty exists over how such an association with injury could arise. It is possible, for example, that mild forms of the condition might come to medical attention for the first time following assessment of an injury (diagnostic bias), or that the contracture could make hand accidents more likely (reverse causation). Preliminary data on associations were small-scale and studies were ill-equipped to address confounding, for example, by age. Somewhat inconclusive findings prompted several orthopaedic textbooks (and current websites) to record the case for work causation as unproven.
17. Dupuytren’s disease was last considered by the Council in the course of its review Work-related upper limb disorders, Cm 6868 (2006). At that time a literature search identified some evidence on occupational causation, including a body of reports reviewed by Liss and Stock in 1996. These authors had concluded that there was ‘good support for an association between vibration and Dupuytren’s contracture’, but the Council found the data insufficient to meet the normal threshold for prescription.
18. Since then, however, further evidence has accumulated. This present review commenced with an updated search of the literature. At this scoping stage new reports were found both in relation to manual work and occupational exposure to hand-transmitted vibration.
19. The Council concluded, however, that ‘manual work’ covered such a broad spectrum of occupational activities, and was defined so openly and generally in research reports, as to render untenable the practical definition of coverage for this group of workers. It was decided, therefore, to limit the review to potential prescription for Dupuytren’s contracture in workers exposed to hand-transmitted vibration, the focus of the MP’s original inquiry.
The Industrial Injuries Disablement Benefit Scheme 20. IIAC is an independent statutory body set up in 1946 to advise the Secretary of State
for Work and Pensions in Great Britain, and the Department for Social Development in Northern Ireland on matters relating to the Industrial Injuries Scheme. The major part of the Council’s time is spent considering whether the list of prescribed diseases for which benefit may be paid should be enlarged or amended.
21. The Industrial Injuries Disablement Benefit (IIDB) Scheme provides a benefit that can be paid to an employed earner because of an occupational accident or prescribed disease.
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The legal requirements for prescription 22. The Social Security Contributions and Benefits Act 1992 states that the Secretary of
State may prescribe a disease where he is satisfied that the disease:
a) ought to be treated, having regard to its causes and incidence and any other relevant considerations, as a risk of the occupation and not as a risk common to all persons; and
b) is such that, in the absence of special circumstances, the attribution of particular cases to the nature of the employment can be established or presumed with reasonable certainty.
23. In other words, a disease may only be prescribed if there is a recognised risk to workers in an occupation, and the link between disease and occupation can be established or reasonably presumed in individual cases.
24. In seeking to address the question of prescription for any particular condition, the Council first looks for a workable definition of the disease. It then searches for a practical way to demonstrate in the individual case that the disease can be attributed to occupational exposure with reasonable confidence. For this purpose, reasonable confidence is interpreted as being based on the balance of probabilities according to available scientific evidence.
25. Within the legal requirements of prescription it may be possible to ascribe a disease to a particular occupational exposure in two ways – from specific clinical features of the disease or from epidemiological evidence that the risk of disease is at least doubled by the relevant occupational exposure.
Clinical features 26. For some diseases attribution to occupation may be possible from specific clinical
features of the individual case. For example, the proof that an individual’s dermatitis is caused by his/her occupation may lie in its improvement when s/he is on holiday and regression when they return to work, and in the demonstration that they are allergic to a specific substance with which they come into contact only at work. It can be that the disease only occurs as a result of an occupational hazard (for example, coal workers’ pneumoconiosis).
Doubling of risk 27. Other diseases are not uniquely occupational. Moreover, when caused by occupation,
they are indistinguishable from the same disease occurring in someone who has not been exposed to a hazard at work. In these circumstances, attribution to occupation on the balance of probabilities depends on epidemiological evidence that work in the prescribed job, or with the prescribed occupational exposure, increases the risk of developing the disease by a factor of two or more.
28. The requirement for at least a doubling of risk follows from the fact that if a hazardous exposure doubles risk, for every 50 cases that would normally occur in an unexposed population, an additional 50 would be expected if the population were exposed to the hazard. Thus, out of every 100 cases that occurred in an exposed population, 50 would do so only as a consequence of their exposure while the other 50 would have been expected to develop the disease, even in the absence of the exposure. Therefore, for any individual case occurring in the exposed population, there would be a 50 per cent chance that the disease resulted from exposure to the hazard,
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and a 50 per cent chance that it would have occurred even without the exposure. Below the threshold of a doubling of risk only a minority of cases in an exposed population would be caused by the hazard and individual cases therefore could not be attributed to exposure on the balance of probabilities; above it, they may be.
29. The epidemiological evidence required should ideally be drawn from several independent studies, and be sufficiently robust that further research at a later date would be unlikely to overturn it.
30. Dupuytren’s contracture has established non-occupational causes and does not have clinical features that differ in cases alleged to arise in an occupational context. The argument for prescription rests, therefore, on reliable evidence of a doubling or more of risk in exposed workers.
Method of investigation 31. The Council’s Research Working Group conducted a literature review, focusing on
research reports on occupation and Dupuytren’s contracture. Account was taken, in particular, of a recent systematic review of evidence by Descatha et al. (2011), which in turn cited nine primary research reports, seven of which indicated a more than doubling of risk from hand-transmitted vibration under some circumstances of exposure. These papers and others identified by the Council’s search were retrieved and evaluated. Additionally, correspondence was conducted with authors of three of the papers, requesting re-analyses particular to the Council’s needs; and one of the Council’s members supplied additional relevant data from a national survey of vibration. Several experts in the health effects of hand-transmitted vibration were also consulted (Appendix 1).
Consideration of the evidence 32. Bovenzi et al. (1994) studied 828 working-aged men from Italy, comprising stone
workers (145 quarry drillers and 425 stonecarvers) and 258 manual controls. The exposed population was long-serving (mean exposure duration 17.4 years) with little turnover, and few workers are likely to have been selected out of employment because of the disease. Levels of exposure to hand-transmitted vibration would have been relatively high.
33. Risks (odds ratios (OR)) were elevated more than two-fold and there was evidence of a dose-response relationship. However, exposure levels in the report were defined in terms of a complex composite of vibration magnitude and time, potentially unusable within the context of the IIDB Scheme. Professor Bovenzi, when requested, kindly provided an alternative analysis of the original data (Table…