Gastrointestinal problems in auto factory shift workers.

Abstract

The research question for this study was: what is the relationship between the shift work and self reported GI symptoms, GI medications, and GI diagnoses. The study was a secondary analysis from a cross-sectional survey: Noise effects on cardiovascular and stress related diseases by Professor Sally L. Lusk. Clock-in and clock-out times were collected post hoc for the 28 day period before participants completed the questionnaires. The subjects were 343 factory workers who were employed at least five years at the plant, in skilled or unskilled job categories, and either White or Black race. The dependent variables were GI diagnoses, GI medications, and GI symptoms. The independent variable was shift work. Subjects worked fixed day or evening shifts. Since their work times varied considerably due to overtime work, four shift work variables were used: assigned shift; number of hours worked; number of night hours worked (between midnight and 5 am); and schedule variability. Control variables were: demographic variables, lifestyle variables (smoking, alcohol use, noise exposure, use of hearing protection), and trait anxiety. Data analysis included multiple regression and logistic regression to test the effects of the shift variables while controlling for the effects of demographic, lifestyle and anxiety variables. The number of subjects on day shift was 225 and on evening was 118. Evening shift had more women, Black race, unmarried, slightly younger age, slightly less years employed, slightly more work hours, 2.7 times more night hours, and more schedule variability. GI symptoms were associated with age, sex, smoking, noise exposure and anxiety. After controlling these, evening shift was associated with 0.41 more symptoms (scale range 0--7; p = .02). Night hours showed a nonsignificant trend for 0.19 more symptoms. An interaction of alcohol use by schedule variability was significant (p = .015). With high alcohol use, as schedule variability increased, GI symptoms increased. With low alcohol use, as schedule variability increased, GI symptoms decreased slightly. Because GI diagnoses were reported by only 23 subjects, bivariate tests were used. A higher percentage of evening workers had a GI diagnosis (11.0% versus 4.4%; p = .02). A contradictory finding was that GI diagnoses were associated with less schedule variability (p = .02). GI medication use was associated with less hearing protection use and increased anxiety and noise. After controlling for hearing protection use, anxiety, and noise, hours worked approached significance (p = .09), and a schedule variability by noise interaction was significant (p = .008). The interaction indicated that when noise was low (for example 81 dBA), as schedule variability increased, use of GI medication increased. In conclusion, evening shift, increased schedule variability, hours worked, and night hours showed some modest adverse relationship to GI function.