A comparison of approaches to modeling the relationship between ergonomic exposures and upper extremity disorders.
BACKGROUND
For a study of upper extremity musculoskeletal disorders among automobile manufacturing workers, an ergonomic exposure index was constructed by summing ten psychophysical (interview) items. Here we explore the sensitivity of the exposure-response relationship to the formulation of that index.


METHODS
Five alternative exposure indices were constructed: three a priori weighting schemes and two sets of weights derived from multivariate regression coefficients. In addition, structural equation modeling was performed with LISREL.


RESULTS
The original index and a priori weighting schemes had similar associations with upper extremity disorders, adjusted for nonoccupational covariates. A reasonable model fit was achieved in LISREL after two modifications; the standardized solution showed that nonneutral postures were significantly related to upper extremity signs and symptoms.


CONCLUSIONS
In this large population, with adequate range of exposures, the exposure-response relationship appeared generally robust to the mathematical formulation of the exposure index. Among the available exposure variables, postural strain had the strongest association.
Punnett
L
L
Department of Work Environment, University of Massachusetts Lowell, MA 01854, USA. lp@uml.edu
van der Beek
A J
AJ
D000328:Adult; D001134:Arm Injuries / Q000209:etiology*; D001336:Automobiles; D003198:Computer Simulation; D006804:Ergonomics; D005260:Female; D006801:Humans; D007221:Industry; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000209:etiology*; D009784:Occupational Diseases / Q000209:etiology*; D011601:Psychophysics; D012307:Risk Factors