Prediction of Tendinitis and Carpal Tunnel Syndrome among Solderers

Abstract

Carpal tunnel syndrome (CTS) is one of the fastest-growing occupational illnesses in the United States. Workers in the meat packaging, newspaper, poultry, textile, and electronics industries suffer from incidence rates as high as 20 to 50 percent per year. The costs associated with this syndrome range from $3500 to $30,000 per case in workers' compensation and medical costs. While numerous occupational and nonoccupational risk factors are known to be associated with CTS, no quantitative thresholds are known to exist. This nested cross-sectional study was designed to determine occupational and nonoccupational risk factors associated with CTS and to develop a predictive linear equation for tendinitis and CTS among the hands of solder touch-up workers in the electronics assembly industry. Subjects were employees of an electronics manufacturing company performing solder touch-up activities on printed circuit boards. Each received a questionnaire, a limited physical examination of the extremities by an occupational physician, and a detailed evaluation of work methods over a standardized series of work tasks. Data collected were used to draft a predictive equation using multivariate statistical techniques including factor analysis, discriminant analysis, and multiple logistic regression. The draft equation was tested on workers for whom the same measurements were collected at a similar yet different workplace from the same employer. By combining the data from both sites, a final equation was developed and its predictive accuracy evaluated. Results indicate that (1) interemployee differences in work practices are important determinants of CTS risk, (2) equations can predict whether or not the hands of exposed workers are likely to have tendinitis or CTS by applying measurements of currently accepted risk factors, (3) work-related risk factors appear to be more important than nonoccupational risk factors such as age and obesity in predicting whether a hand is likely to have CTS or not, and (4) interactions between occupational risk factors (angles and frequencies) are important predictor variables.