Objective There is a lack of studies investigating social capital at the workplace level in small and relatively homogeneous work-units. The aim of the study was to investigate whether work-unit social capital predicts a lower risk of individual long-term sickness absence among Danish hospital employees followed prospectively for 1 year.

Methods This study is based on the Well-being in HospitAL Employees cohort. The study sample consisted of 32 053 individuals nested within 2182 work-units in the Capital Region of Denmark. Work-unit social capital was measured with an eight-item scale covering elements of trust, justice and collaboration between employees and leaders. Social capital at the work-unit level was computed as the aggregated mean of individual-level social capital within each work-unit. Data on long-term sickness absence were retrieved from the employers’ payroll system and were operationalised as ≥29 consecutive days of sickness absence. We used a 12-point difference in social capital as the metric in our analyses and conducted two-level hierarchical logistic regression analysis. Adjustments were made for sex, age, seniority, occupational group and part-time work at the individual level, and work-unit size, the proportion of female employees and the proportion of part-time work at the work-unit level.

Results The OR for long-term sickness absence associated with a 12-point higher work-unit social capital was 0.73 (95% CI 0.68 to 0.78). Further, we found an association between higher work-unit social capital and lower long-term sickness absence across quartiles of social capital: compared with the lowest quartile, the OR for long-term sickness absence in the highest quartile was 0.51 (95% CI 0.44 to 0.60).

Conclusion Our study provides support for work-unit social capital being a protective factor for individual long-term sickness absence among hospital employees in the Capital Region of Denmark.