A medical assessment process for a large volume of medico-legal compensation claims for hand arm vibration syndrome

Transcription

1 Occupational Medicine 2003;53: DOI: /occmed/kqg011 A medical assessment process for a large volume of medico-legal compensation claims for hand arm vibration syndrome I. J. Lawson 1 and K. L. McGeoch 2 Background The judgement on preliminary issues of nine lead cases of suspected hand arm vibration syndrome (HAVS) in former coal miners in the UK ruled that there was evidence of damage and breach of duty of care (Armstrong and Others v. British Coal, 1996). In anticipation of > cases and at significant cost, a handling agreement was prepared in This recommended a single medical assessment process (MAP) to determine general damages for which almost 200 doctors attended 2 days of training. Aims Methods Results Conclusion Key words This paper outlines the assessment process and the results to date. Seventeen test centres across the UK were commissioned. Standardization of the performance by both the doctors and technicians within individual examination centres and across all centres was necessary. A pragmatic solution using best available assessment techniques, whilst at the same time coping with the large number of claimants, was required. Doctors were trained to administer questionnaires for clinical symptoms, past medical history and occupational history, and a standardized clinical assessment pro-forma. Three standardized tests were used: vibrotactile thresholds, thermal aesthesiometry and cold water provocation testing. A modification of the Stockholm Workshop Scales and scoring system was adopted. At time of writing, claimants had been assessed by the MAP. Analysis of results showed that 5% were assessed at 0SN, 15% at 1SN, 18% at 2SN (early), 28% at 2SN (late), 33% at 3SN, 21% at 0V, 13% at 1V, 38% at 2V and 28% at 3V. It is concluded that the MAP is a practical and time-efficient tool for assessing a large volume of claimants with suspected HAVS. Further analysis of the process and staging is required to confirm its validity as a medico-legal examination. Hand arm vibration syndrome; medico-legal. Received 29 January 2002 Revised 23 September 2002 Accepted 11 November 2002 Background The judgment on preliminary issues of nine lead cases of suspected hand arm vibration syndrome (HAVS) in 1 Rolls-Royce plc, PO Box 31, Derby DE24 8BJ, UK Stanely Avenue, Paisley PA 2 9LB, UK. Correspondence to: I. J. Lawson, Rolls-Royce plc, PO Box 31, Derby DE24 8BJ, UK. Tel: ; ian.lawson@rolls-royce.com former British coal miners ruled that there was evidence of damage and breach of duty of care (Armstrong and Others versus British Coal, 1996) [1]. The court used the term vibration white finger. The ruling took account of expert scientific evidence from major publications on the long-term effects of hand-transmitted vibration. On 31 December 1998, the British Coal Corporation ceased to exist and its liabilities were taken over by the Department of Trade and Industry (DTI). Copyright Society of Occupational Medicine. Printed in Great Britain. All rights reserved /03 302

2 I. J. LAWSON AND K. L. MCGEOCH: ASSESSING COMPENSATION CLAIMS FOR HAVS 303 The claimants were represented by the Claimants Steering Group (CSG). This group acts on behalf of some 70 different firms of solicitors. To avoid further lengthy expensive court cases, following exhaustion of the appeal process, the main parties reached a handling agreement recommending a single medical assessment procedure (MAP) to determine general damages. This examination was to determine the presence or absence of disease caused by previous exposure to occupational vibration and, if present, the extent of general damage. From the outset, it was known that there would be a large number of claimants (at present > cases, but the authors estimate that this represents only 50% of the mining population) and high costs in processing the claims, assessment and compensation (at present around 3 billion Sterling). Compensation to an injured worker consisted of: 1. general damages varying with the extent of the injury; 2. damages for handicap in the labour market; 3. special damages for disability in the more seriously injured claimants, following a second completely separate assessment process; these carried higher financial awards than the general damages and labour market handicap awards (1 and 2). One of the authors (K.L.M.) was requested to produce a medical specification which would be the basis of the single medical examination for (1) and (2) above. With the agreement of the DTI, a group of four, with wide experience of the problems of vibration-induced disease, was enlisted and became the Independent Medical Advisory Group (IMAG). The process described in this paper refers only to the general damages assessment and labour market handicap. The severity of disability was outside the remit of the IMAG. The only instruction from the DTI was that the process should be fair to the claimant and fair to the taxpayer. To our knowledge, a similar exercise on this scale had not previously been attempted. The format created under the guidance of Professor W. Taylor and in use by Mitsui Babcock since 1990 and Rolls-Royce plc since 1995 was taken as the basis for the examination process. It was made clear by the DTI that there were tight time-scales for the implementation of a satisfactory examination process and for completion of the contract. From the outset, it was obvious that, as well as medical considerations, there were political and legal dimensions. There were protracted negotiations, as every detail of the assessment process had to be agreed by the interested parties (CSG, DTI). It also resulted in the parties agreeing some aspects of the medical assessment process without referral to the IMAG. The CSG initially did not want the type of examination process recommended by the IMAG. Their experience was with vascular surgeons who did not use the proposed format or any form of standardized testing. Both main parties favoured the simple grading of vibration-induced damage found in the Taylor/Pelmear Classification and it was only with great difficulty that they were persuaded to recognize damage to the neurological system and accept the use of the Stockholm Workshop Scales (SWS) [2]. There was no possibility of the parties accepting an assessment of other associated upper-limb musculo-skeletal abnormalities. The parties finally agreed scales for (1) and (2) based on the SWS. Neither the IMAG nor the examining doctor had any involvement in setting the amount of an award to any individual claimant, other than the arrival at an SWS staging. The problem for the IMAG was to create a MAP that would give similar results from centres across the UK. Initially, there were to be 12 centres, but this number was increased to 17. The need for standardization across these centres was critical to the success of the whole process, which had to be compatible with the projected time-scales and with reasonable costs. This requirement for standardization meant that the examinations had to be software driven. Initially, the plan was to limit data entry, as far as possible, to yes/no tick-boxes. Scoring systems for both the standardized tests and staging by the SWS were developed. However, experience showed that audit was impossible where only yes/no boxes had been completed. It was necessary to include more details of the history and of the doctor s findings. Three pilot centres were commissioned to test the MAP. This required training of both doctors and nurse/ technicians. After some months, the pilot trial was judged to be fit for purpose and a contract was put out to open tender. The contract was awarded with a start date of 1 August Shortly after the contractor was in place, the role of the IMAG was complete. It was superseded by a medical reference panel (MRP) to oversee quality assurance aspects and advise on other problems. Unfortunately, lack of agreement by the parties meant that problems such as the position regarding carpal tunnel syndrome (CTS) remained unresolved at the start of the main contract. A claims-handling company was employed by the DTI to liaise with the claimants solicitors. Because of poor Coal Board records of exposure to vibration, a simplistic grading was used: 1. claimants who worked in situations where there was known exposure to vibration that was probably excessive; 2. claimants who were exposed to vibration of unknown severity;

3 304 OCCUPATIONAL MEDICINE 3. claimants with no known exposure to vibration. The handling company arranged appointments at appropriate geographical centres for claimants in groups (1) and (2). It issued the claimants details and years of exposure to vibration according to the Coal Board s records. These were the only exposure data available. Several hundred different types of vibratory tool were in use over the relevant period. The history of exposure to vibration given by the claimants during the examination rarely agreed with that suggested by the Coal Board records. All claimants attending for examination underwent the full MAP process, even if the history excluded the diagnosis of HAVS. Methods Training Doctor training Doctors were recruited by a medical agency to criteria set by the IMAG. A training course consisted of 10 or fewer doctors and lasted 2 days. The first day covered all aspects of HAVS. On the second day, the doctors were introduced to the MAP pro-forma. During training, the doctors were advised to avoid asking leading questions whenever possible and to let the claimant describe in detail their symptoms and problems. Thereafter, the questions on the pro-forma were put to the claimant. The course ended with an examination that consisted of simulated cases and a multiple-choice questionnaire. A satisfactory assessment was required before a doctor was allowed to examine claimants. The training course for the doctors was designed and performed by the authors. Nurse/technician training The nurse/technicians were trained to perform the standardized tests. Initially, the course lasted 1 day, but had to be extended by half a day. Medical Assessment Process During creation of the MAP, consideration had to be given to practicality, repeatability, time and costs. During the pilot trial, the doctors were expected to examine three claimants during a 4 h session. In the actual contract, the parties agreed, for economic reasons, to increase the throughput to four claimants per session. Centres that have multiple sets of equipment have examined >100 claimants in a week. The scope of the MAP was limited to the diagnosis or otherwise of HAVS and to grading the extent of the damage caused by occupational vibration using the SWS. The question of prognosis was outside the MAP s remit. Where the condition may appear to have improved, for example where a claimant was no longer exposed to cold and therefore did not have vaso-spastic attacks, the doctor was expected to record these facts. The final award then depends on negotiation between the parties. If an unrelated diagnosis was found, there were mechanisms for notifying the claimant s general practitioner. All questionnaires and test procedures were software driven. The tests were included to overcome the total reliance on the claimant s history. It was accepted that none of the tests had the sensitivity or specificity for individual diagnosis. Vibrotactile thresholds (VTT), thermal aesthesiometry (TA) and cold water provocation (CPT) were chosen as the three standardized tests, in line with publications by the UK Health & Safety Executive (HSE) [3]. This choice of tests was in keeping with the recommendations in other publications [4 7]. The terminology standardized tests was used because it was recognized that, apart from the CPT, the tests were not truly objective. Standardization refers to all centres using tests that were calibrated and performed in the same tightly controlled manner. The criteria for the diagnosis of HAVS were a history of exposure to vibration and complaint of appropriate symptoms, supported by evidence of abnormalities on clinical examination and results from the standardized tests. The stages of the assessment were: 1. questionnaire to ascertain any history of symptoms of HAVS; 2. questionnaire to help with the differential diagnosis and detection of any possible dual pathology; 3. clinical examination of the claimant by the doctor; 4. performance of the standardized tests; 5. scoring system and guidance on staging of the sensorineural and vascular components; 6. staging using the SWS. Details Symptomatology questionnaire At the start of the examination, due to the lack of adequate exposure records and time restraints, the doctor was only able to take a short history of vibration exposure. Questioning without the use of leading questions was encouraged; for example, how do your hands trouble you?. This was followed by careful and discreet questioning to elicit symptoms of blanching or other colour changes. If there was a history of cold-induced whiteness, information was recorded on when this was first noticed and whether episodes were all year round or confined to

4 I. J. LAWSON AND K. L. MCGEOCH: ASSESSING COMPENSATION CLAIMS FOR HAVS 305 winter. A blanching score was recorded as described by Rigby and Cornish [8] and Griffin [9]. A description of blueness was accepted, but not coldness without a change of colour. The effects on job, hobbies and sport were also recorded. Identical questions were asked about numbness and tingling. Circumstances of tingling and numbness were ascertained after the use of vibrating tools, in response to cold, during attacks of whiteness or at other times. For the sake of standardization, cut-off points had to be decided with regard to the terms transient and persistent tingling and numbness, as described in the SWS. As no published guidance on these aspects could be found, the IMAG agreed that tingling and/or numbness for >20 min was regarded as abnormal. Persistent tingling and/or numbness of 2 h or more was considered to be abnormal. The effects of tingling and numbness on job, hobbies and sport were recorded. Nocturnal wakening with tingling or numbness was noted. The answers may raise the possibility of an entrapment neuropathy. Symptoms of pain, swelling, stiffness and weakness of grip were recorded. Details of loss of dexterity in a warm environment were taken. Past medical history questionnaire Past medical history details, including smoking and alcohol consumption, were recorded. The list of possible dual pathological/co-morbid conditions was potentially huge. It was very unlikely that many of these conditions would complicate the examination; however, at the insistence of one party, six such conditions were accepted: cervical spondylosis; osteoarthritis; rheumatoid arthritis; cardiovascular and peripheral vascular disease; diabetes mellitus; and primary Raynaud s disease. Emphasis was placed on ascertaining whether white finger attacks occurred prior to entering the industry, whether feet, ears or nose were affected and whether there was a family history of Raynaud s disease in firstdegree relatives. Enquiry was made about attacks being precipitated by emotion [10]. Medication, particularly of those drugs that could either effect symptom presentation or the CPT (e.g. betablockers or calcium channel blockers), was recorded, including any effect on symptomatology of starting or stopping such medication. Clinical examination The doctors were required to examine the claimant, paying particular attention to abnormalities in cervical spine, shoulders, elbows, wrists and hands, specifically looking for signs of arthritis, circulatory problems, trophic changes, connective tissue problems or muscle wasting. Blood pressure in both arms, radial and ulnar pulses, Allen s test [11] and Adson s test [12] were performed, as were Phalen [13] and Tinel tests [14]. The doctor carried out tests of dexterity and grip strength. A number of tests were reviewed. The Purdue pegboard test the PPT [15,16] was deemed to be the most suitable, as it included a time factor and had published age-related normative data. The Jamar dynamometer [17] was used to measure grip strength, because of the availability of normative data. The doctor did not receive the results of the standardized tests until the clinical examination was completed. Performing the standardized tests The standardized tests used were TA, VTT and CPT, the equipment for which was manufactured by HVLab, University of Southampton. TA and VTT were carried out on both index and little fingers in order to test the median and ulnar nerves. The VTT was measured at 31.5 and 125 Hz. The CPT was carried out with thermocouples attached to each of the eight fingers. After a settling period of 2 min, the hands were placed inside plastic gloves immersed up to the wrist for 5 min at 15 C and then finger skin temperature was monitored for 10 min after exiting the bath. Scoring system and guidance for staging sensorineural and vascular components using the SWS The scoring system was adopted from previous studies and available normative data from the existing laboratories in the UK [3,18,19] were pooled, as shown in Table 1. A modification of the SWS, recognizing that tingling was as important as numbness, is shown in Table 2. The assessment process requires separate assessment for each hand. Final staging It was emphasized that if the history was not consistent with a diagnosis of HAVS, the doctors had to record their reasons for this decision. Sensorineural staging As stage 2SN sensorineural was thought to cover a wide range of sensorineural damage, it was divided into early and late parts. The temperature neutral zone score for each hand was added to the VTT result, to give a total sensorineural hand score, i.e. TA + VTT. If loss of dexterity in a warm environment was diagnosed and there was TA + VTT hand score 9, then a 10 was added to this result, but only if the PPT was abnormal. All three factors were necessary for a stage of 3SN. This ensured that only those with significant

5 306 OCCUPATIONAL MEDICINE Table 1. Scoring system used for the standardized tests Vibrotactile threshold (VTT) index and little finger At 31.4 Hz <0.3 ms² = ms², <0.4 ms² = ms² = 2 At 125 Hz <0.7 ms² = ms², <1.0 ms² = ms² = 2 Thermal aesthesiometry (TA) 1º/s, index and little finger Temperature neutral zone (TNZ) <21ºC = 0 21ºC, <27ºC = 2 27ºC = 4 Cold provocation test (15ºC for 5 min, 10 min recovery) T(+4º) 300 s = 0 >300 s, 600 s = 1 >600 s = 2 Table 2. Modification of the Stockholm Workshop Scales Assessment Stage Criteria Left hand Right hand Sensorineural staging 0SN Vibration exposure but no symptoms 1SN Intermittent numbness and/or tingling with a sensorineural score of 3, <6 2SN (early) Intermittent or persistent numbness and/or tingling, reduced sensory perception with a score of 6, <9 2SN (late) As 2SN (early), but with a score of 9, 16 3SN Intermittent or persistent numbness and/or tingling, reduced manipulative dexterity and an SN score of 19 Vascular staging 0V No attacks 1V Attacks affecting only the tips of the distal phalanges of one or more fingers, usually a blanching score of 1 4 2V Occasional attacks of whiteness affecting the distal and middle (rarely also the proximal) phalanges of one or more fingers, usually a blanching score of V Frequent attacks of whiteness affecting all of the phalanges of most of the fingers, usually a blanching score 18 4V As 3V plus trophic changes neurological damage were assigned to this category. Once again, if there was a difference between the history and the doctor s final staging, an explanation had to be recorded. Vascular staging If the history was in keeping with the diagnosis of the vascular component of HAVS, the history, examination findings and clinical test results determined the overall staging. There was a lack of normative data for the CPT. Such data as were available from three laboratories operating in the UK were pooled to set a mean and two standard deviations for the time to rewarm by 4 C from the lowest finger temperature. This was found to be T + 4 < 300s. If one finger had a result 300 s, then the whole CPT was classed as abnormal. It was our opinion at the start of process that an abnormal result was strong supportive evidence of vascular damage. However, we appreciated that a large number of studies questioned the sensitivity, specificity and false-negative results of this test, particularly when such tests were performed during the summer months [20]. Studies have been reported in the literature showing that the vascular symptoms correlated with sensorineural test results [21,22]. In the presence of a good history of finger blanching, but a normal CPT, the doctors were allowed to take account of the sensorineural test results when arriving at a vascular staging. It is the authors experience that high vascular stages rarely occur when all the tests are either normal or show minimal abnormalities. The doctors were asked to give an opinion on what percentage of the claimant s condition was as a result of their exposure to vibration during their time at the Coal Board. It was recorded if one of the six dual pathological/co-morbid conditions was present. This led to a small number of claimants receiving a discounted award. They also recorded whether there was any evidence of CTS based on the history and clinical examination. Results Over claimants have been through the process and the overall breakdown by stages is shown in Table 3. The mean age of claimants was 56 years (range years) and mean exposure 24.5 years (range 5 45 years),

6 I. J. LAWSON AND K. L. MCGEOCH: ASSESSING COMPENSATION CLAIMS FOR HAVS 307 Table 3. Sensorineural and vascular staging for right hand (n = ) Sensorineural staging right hand Vascular staging right hand 0SN 1SN 2(e)SN 2(l)SN 3SN 0V 1V 2V 3V 4V No % Table 4. Years of exposure Range 40 Minimum 5 Maximum 45 Mean SD as shown in Table 4. The average testing times were: TA, 31 min; VTT, 18 min; and CPT, 21 min. The doctor time averaged at 38 min, with an overall assessment time of 1 h 48 min. The assessment process will be subject to ongoing audit and the final analysis of results is clearly not complete. Discussion This contract will produce the largest worldwide database on vibration-exposed workers. Unfortunately, the Coal Board s records of vibration exposure and dosage were either very poor or non-existent. It has not been possible to reach any reliable dose-related findings. The contract included very tight time-scales for opening of the centres (originally 12 and now 17 in number), throughput of claimants and completion of the contract. This led to considerable problems in agreeing aspects of the MAP without adequate trial. There were important unresolved issues between the parties, as follows. 1. Was CTS part of HAVS, or was a separate specification required? 2. Were there dual pathological conditions which could influence the presenting signs and symptoms and, if so, did it justify a discounted award? 3. The problem of late onset of symptoms, i.e. when symptoms began >2 years after exposure to vibration ceased. 4. How should co-morbid conditions, not related to HAVS but interfering with the assessment of any injury, be measured? During the pilot scheme, there was auditing of the different centres and of the individual doctors and nurse/ technicians. However, sufficient support was not available to cover the larger numbers involved under the contract. After a year, the data showed unacceptable variations between centres and also individual doctors. Once this was recognized, far greater effort was put into the auditing process and retraining seminars were held for all participants. This huge database has allowed the MRP to audit both centres and doctors. It can analyse the results of the individual tests and their association with the Stockholm staging, look at the prevalence of HAVS in this population and also the prevalence of conditions such as Dupuytren s contracture and diabetes mellitus. By completion of the contract, it is expected > miners will have been examined. The system allows for ~1000 claims to be processed per week. The age range is wide. The presence of so many elderly miners brought its own complications. The medical specification had to be based on evidence available from normal working populations. This has probably not been ideal for the older miners with all the different degenerative diseases. The MAP was an attempt to overcome total reliance on the claimant s history. Unfortunately, coaching, while probably not widespread, has undoubtedly been a factor. Several pamphlets giving guidance became available, as did a web page which gave accurate advice before it was rapidly closed down. The tests used were thought to be those best suited to the requirements of all parties, taking into consideration the time-scales and costs. Serious consideration was given to the inclusion of nerve conduction studies and electromyography. Both of these tests had to be foregone for the following reasons: 1. the examination had to take place at one site and on one occasion; 2. neither the National Health Service (waiting time many months) nor the private sector could cope with the numbers involved and practice across the UK was not uniform; 3. the overall costs would have greatly increased. The MAP and thus the database was created and funded by the DTI, purely for the purpose of rapidly examining a large number of claimants in a medicolegal situation in order to avoid protracted, potentially adversarial court proceedings. It was not constructed with research as its primary purpose. However, the MRP believe that, in spite of the in-built bias due to all

7 308 OCCUPATIONAL MEDICINE examinees being claimants, much useful data can be retrieved. Future papers will look at many aspects of this unique database. The use of the CPT in assessing vascular damage and staging by the SWS will be fully investigated in one paper. A separate paper will consider the use of TA and VTT in grading the neurological component. The evidence of CTS found during these examinations requires detailed analysis. The association of the neurological tests and the vascular component also requires scrutiny. Conclusions The MAP has been shown to be a practical and timeefficient tool for assessing a large volume of claimants with suspected HAVS. Many lessons have been learned throughout the process that would help avoid mistakes next time. Further analysis of the data is required before recommendations can be made regarding the use of a MAP-like process in the future. However, expensive litigation schemes are never likely to based entirely on medical grounds, nor are they likely to be free of the political and partisan interference experienced with this contract. Acknowledgements The authors wish to acknowledge Professors C. L. Welsh and M. J.Griffin for their participation, with the authors, in IMAG and Professor Frank Burke and Mr George Proud for their participation, with the authors, in the MRP. References 1. Armstrong WJ and Others v. British Coal Corporation, Reference no.: U Judgement on preliminary issues (High Court of Justice Queen s Bench Division, Law Courts, Newcastle Upon Tyne), Brammer AJ, Taylor W, Lundborg G. Sensorineural stages of the hand arm vibration syndrome. Scand J Work Environ Health 1987;13: Lindsell CJ, Griffin MJ. Standardised diagnostic methods for assessing components of the hand arm vibration syndrome, Contract Research Report 197. Southampton: Institute of Sound and Vibration Research, University of Southampton for HSE, McGeoch KL, Taylor W, Gilmour WH. The use of objective tests as an aid to the assessment of the sensorineural stages of the Stockholm Classification in HAVS. Proceedings of the 6th International Conference on HAV. Essen: Druckzentrum Sutter & Partner GmbH, 1992; Pelmear PL, Wong L, Dembeck B. Laboratory tests for the evaluation of hand arm vibration syndrome. Proceedings of the 6th International Conference on HAV. Essen: Druckzentrum Sutter & Partner GmbH, 1992; Proceedings of the Stockholm Workshop, Working Group 2, 1994; Health & Safety Executive (HSE). Hand Arm Vibration. London: HSE, 1994; Rigby TA, Cornish D. Vibration Syndrome Research Panel. Guest Keen, and Nettlefolds (GKN Forgings Ltd) and Rolls-Royce, Derby (England), Griffin MJ (ed.). Handbook of Human Vibration. London: Academic Press, 1990; Taylor W, Pelmear PL. Introduction. In: Taylor W, Pelmear PL, eds. Vibration White Finger in Industry. London: Academic Press, 1975; XVII XXII. 11. Ashbell TS, Kutz JE, Kleinert HE. The digital Allen test. Plast Reconstr Surg 1967;39: Adson AW. Surgical treatment for symptoms produced by cervical ribs and the scalenus anticus muscle. Surg Gynecol Obstet 1947;85: Heller L, Ring H, Costeff H, Solzi P. Evaluation of Tinel s and Phalen s signs in diagnosis of the carpal tunnel syndrome. Eur Neurol 1986;25: Mossman SS, Blau JN. Tinel s sign and the carpal tunnel syndrome. Br Med J 1987;297: Reddon JR, Gill DM, Gauk SE, Maer MD. Purdue pegboard: test retest estimates. Percept Mot Skills 1988;66: Tiffin J, Asher EJ. The Purdue pegboard norms and studies of reliability and validity. J Appl Psychol 1948;32: Mathiowetz M, Kashman N, Volland G, Weber K, Dowe M, Rogers S. Grip and pinch strength: normative data for adults. Arch Phys Med Rehabil 1985;66: Lawson IJ, Nevell DA. Review of objective tests for the hand arm vibration syndrome. Occup Med 1997;47: McGeoch KL, Harper Gilmour W, Taylor W. Sensorineural objective tests in the assessment of the hand arm vibration syndrome. Occup Environ Med 1994;51: Gautherie M. Clinical studies of the vibration syndrome using cold stress test measuring finger temperature. Presented at the 7th International Conference on Hand Arm Vibration, Prague. Centr Eur J Publ Health 1995;3: Coutu-Wakukzyk G, Brammar AJ, Piercy JE. Association between quantitative measures of tactile acuity and hand symptoms reported by operators of power tools. J Hand Surg 1997;22: McGeoch KL, Gilmour WH. Cross sectional study of a workforce exposed to hand arm vibration with objective tests and the Stockholm workshop scales. Occup Environ Med 2000;57:35 42.