Background: [corrected] This paper focuses on the relationship between sickness absence rates certified as attributable to common (non-work-related) diseases and occupational categories.
Methods: A cohort of 2,909 workers from an urban bus company was analysed from 1994 to 1996 (8,388.7 person-years), who reported 2,893 non-work-related sickness absence spells of three days or more (78% of all sickness absence spells in the period). Rates of sickness absence were calculated and an extension of the Andersen-Gill approach to proportional hazards modelling was used to adjust covariables.
Results: Assistant staff (35.63 per 100 person-years), and bus drivers (37.23) had the highest incidence rates. After adjusting for demographic variables, employment duration and health status, it was found that all occupational categories had a significant rate ratio (RR) in comparison to the manager category. The strongest positive associations were found among bus drivers (RR = 2.45; 95% CI: 1.52-3.97), assistant staff (RR = 2.57; 1.67-3.94), and technical staff (RR = 2.42; 1.57-3.74).
Conclusion: Occupational category was an important predictor of sickness absence incidence certified as attributable to common disease. Further research on the associations between working conditions and sickness absence needs to take into account the distinction between sickness absences due to work-related diseases and those due to common diseases.