ASSOCIATION OF SEMEN QUALITY AND OCCUPATIONAL FACTORS - COMPARISON OFCASE-CONTROL ANALYSIS AND ANALYSIS OF CONTINUOUS-VARIABLES

Objective: To compare two statistical approaches, case-control and ana lysis of continuous parameters of semen, in examining the relationship between occupational exposures and male reproductive function, Design : Case-control study, Setting: Males providing semen samples at a univ ersity infertility clinic, Patient(s): Nonvasectomized males who provi ded at least one semen sample at an infertility clinic, Main Outcome M easure(s): Standard clinical semen analysis, Result(s): Analyses using a dichotomous dependent variable did not uncover significant associat ions between any occupational factor and infertility case status, Howe ver, linear models incorporating continuous variables identified a num ber of occupational factors that were associated with specific paramet ers of semen, A reduction in percentage of progressive sperm and an in crease in percentage of coiled tail sperm defects in welders, compared with unexposed subjects, were found. Significant dose-response relati onships between level of perceived job stress and percentage of progre ssive sperm, total motile count, morphology, abnormal heads, and coile d tail defects were found. Conclusion(s): The findings suggest that su btle changes in semen variables, possibly associated with workplace ex posure, may be detected only with parametric analyses of continuous va riables of semen. (C) 1998 by American Society for Reproductive Medici ne.