Incidence of sickness absence by type of employment contract: one year follow-up study in Spanish salaried workers

BACKGROUND: To examine the differences in the incidence of registered sickness absence by type of employment contract in a large representative sample of salaried workers in Spain in 2009. METHOD: A study of 653,264 salaried workers covered by the Social Security system who had 133,724 sickness absence episodes in 2009. Crude and adjusted rate ratios and their corresponding 95 % confidence intervals (CIs) were calculated with Poisson regression models. RESULTS: The incidence rate per 100 workers-year of sickness absence for temporary workers (IR = 32.2) was slightly higher than that of permanent workers (IR = 28.9). This pattern was observed in both men (RR = 1.12; 95 % CI 1.10–1.14) and women (RR 1.11; 95 % CI 1.09–1.12). However, after adjusting for age, company size, and occupational category, the differences disappeared in men ((a)RR = 1.01; 95 % CI 0.99–1.02) and decreased in women ((a)RR = 1.06; 95 % CI 1.04–1.07). CONCLUSION: Our findings provide evidence on the independence of sickness absence benefits from the type of employment contract as well as on the nonexistence of incentives for taking sickness absence in workers with a permanent employment contract. In the context of increasing market flexibility, these results show a positive functioning of the Social Security system. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13690-016-0152-x) contains supplementary material, which is available to authorized users.