INFLUENCE OF BODY-MASS INDEX AND WORK ACTIVITY ON THE PREVALENCE OF MEDIAN MONONEUROPATHY AT THE WRIST

Objective-To determine which proposed risk factor, work activity (indu strial v clerical), body mass index (BMI), or other demographic factor s had the most influence on the prevalence of median mononeuropathy at the wrist, and if there was an interaction between the risk factors. Methods-This was a cross sectional study of active workers at five dif ferent worksites; four were industrial sites and one was clerical. 527 workers were recruited-164 clerical and 363 industrial. The presence of a median mononeuropathy in either hand was measured by electrodiagn ostic techniques comparing median and ulnar sensory latencies. Results -30% of workers had an abnormality of the median sensory nerve at the wrist (34% of the industrial v 21% of the clerical workers). The adjus ted risk for industrial workers was twice that of clerical workers. Ob ese workers (BMI > 29) were four times more likely to present with a m edian mononeuropathy than workers who were normal or slender (BMI <25) . There was no significant interaction between BMI and worksite in rel ation to median mononeuropathy. Increasing age was also related to an increased risk of median mononeuropathy. Conclusions-Obesity, industri al work, and age are independent risk factors that influence the preva lence of median mononeuropathies among active workers.