Director; Occupational and Environmental Health Program; University of Massachusetts; Medical Center; Worcester, MA (Pransky)
Department of Neurology; University of Massachusetts; Medical Center; Worcester, MA (Long)
The Authors Reply: Mr Guldalian's letter raises questions about several important issues that deserve clarification. Although employee screening is not a pure science, one would hope that there are at least some objective data to justify a procedure that may have deleterious health and economic effects by creating unfounded fears about future disease and depriving workers of income.
Pre-employment testing may be an acceptable approach to risk reduction if the screening procedure is acceptable to workers, technically and economically feasible, has reasonable predictive value, the risks are job-related and significant, and other, more acceptable alternatives are unavailable.1 The Americans with Disabilities Act has defined a risk that is sufficient to warrant exclusion, a direct threat, as"a significant risk to the health or safety…that cannot be eliminated by reasonable accommodation."2 There are no published data that suggests that pre-employment nerve conduction screening will meet these criteria or that asymptomatic persons with a positive result pose a direct threat. A recent investigation by Werner et al concluded that asymptomatic formal nerve conduction abnormalities did not predict future risk for carpal tunnel syndrome in industrial workers.3 The prevalence of asymptomatic formal nerve conduction test abnormalities in workers is generally reported to be in the range of 10%-20%, slightly higher in those with hand-intensive occupations; the vast majority of these asymptomatic persons have had an entire career without diagnosis or treatment for the carpal tunnel syndrome.4,5 Thus even if a screening test is followed by a confirmatory test, a confirmed abnormality in an asymptomatic person has little value in predicting risk of future injury.
Our study raised further concerns about the accuracy of these devices, the high number of false-positive and false-negative results, and significant test-retest instability, which diminishes the value of longitudinal data. This raises serious concerns about using these devices to establish a baseline in workers who are entering hand-intensive, high-risk occupations, where the goal of testing is to deny work-relatedness of subsequent CTS claims if slowing was present at initial examination.
Given the absence of scientific credibility, why do the makers of these devices continue to enjoy success in promoting their use for employment examinations? Several reasons are apparent. First, employers may prefer to exclude workers at risk rather than take on the more difficult task of re-engineering the workplace to reduce risks for all employees. Second, there has been much confusion about the role of these devices in reducing workers' compensation costs; for example, in the instance cited by Mr Guldalian, the reduction was the result of a comprehensive, multi-faceted program, and cannot be attributed to pre-placement screening. Finally, the Equal Employment Opportunity Commission (EEOC) has not completed litigation in an important case of employment discrimination that is directly relevant,6 and thus the promise of adverse legal consequences for those who discriminate based on these tests has not yet been realized. Nevertheless, the EEOC's Director of ADA Policy and assistant legal counsel advises that redirecting potential employees away from jobs based on this type of screening is a risky policy and would be an ADA violation, as the future risks are speculative and not based on objective evidence.7 Employers should be aware that workers who have been excluded from a job because of false-positive tests may not only sue for employment discrimination, but also for the adverse consequences of an erroneous diagnosis. Mr Guldalian suggests that screening, further testing for those with abnormalities, and redirection to other jobs can occur without discrimination. Yet few employers have a sufficient variety of available, equivalent jobs or willingness to pay for expensive nerve conduction tests on at least one of every 10 job applicants to satisfy his criteria for implementation of such a program without discrimination. Although CTS has received much press, it represents less than 10% of all cumulative trauma disorders, and these tests have no bearing on future risk for tendinitis, epicondylitis, and other disorders due to repetitive motion, which collectively may be much more prevalent and costly than CTS in many workplaces.
Mr Guldalian states that, "according to the ADA, none of these tests can be used for pre-employment testing, as suggested in the discussion." The ADA indeed prohibits medical testing before a conditional offer of employment, but in the Act, the term "pre-employment" refers to all testing done before employment commences, including permitted medical evaluations.8
We apologize for lack of information on the specific model used; however, the comparison for NP to EDS was indeed appropriate, as we used the raw data from the Neurosentinel to ascertain stimulus to peak latency. The testing was performed in the winter of 1995.
Glenn Pransky, MD, MOccH
Director; Occupational and Environmental Health Program; University of Massachusetts; Medical Center; Worcester, MA
Randall Long, MD
Department of Neurology; University of Massachusetts; Medical Center; Worcester, MA
1. Pransky GS, Frumkin H, Himmelstein JS. Decision-making in worker fitness and risk evaluation. Occupational Medicine: State of the Art Review. 3:2. Philadelphia: Hanley and Belfus; 1988:179-192.
2. Americans with Disabilities Act of 1990, Title 1, Section 101(3), Direct Threat.
3. Werner RA, Franzblau JW, et al. Use of screening nerve conduction studies for predicting future carpal tunnel syndrome. Occup Environ Med. 1997;54:96-100.
4. Bingham RC, Rosencrance JC, Cook TM. Prevalence of abnormal median nerve conduction in applicants for industrial jobs. Am J Ind Med. 1996;30:355-361.
5. Nathan PA, Keniston RC, Lockwood RS, Meadows KD. Tobacco, caffeine, alcohol, and carpal tunnel syndrome in American industry: a cross-sectional study of 1464 workers. J Occup Environ Med. 1996;38:290-298.
6. Equal Employment Opportunity Commission vs Rockwell International, Inc.
7. [Anonymous.] Nerve conduction studies can lead to ADA violations. Occup Manage. 1997;7:144-145.
8. Americans with Disabilities Act of 1990, Title 1, Section 102 (2), Pre-employment Examinations, paragraph (3), Employment Entrance Examinations.
Readers are invited to submit letters for publication in this department. Submit them to: The Editor, Journal of Occupational and Environmental Medicine, PO Box 370, Bryn Mawr, PA 19010. Letters should be typewritten and double spaced and should be designated”For Publication.”
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