level (LDSL). Moreover, the correlations of the WLQ-subscales with functional disability and physical health were lower or similar in HDSL participants compared to LDSL participants. Conclusion This study provides the first evidence that measurement properties of the WLQ-16 may vary by depressive symptom level in workers who returned to work after musculoskeletal disorders. More research is needed to better understand how health-related work functioning measures perform in workers with depressive symptoms. Objectives To identify the role of lifestyle factors, work-related factors, and work engagement on health, work ability, and sickness absence. Methods Employees from two companies were invited to participate in a longitudinal study with questionnaires at baseline and six-month follow-up (n = 612, response: 40%). Lifestyle-related factors (physical activity, fruit and vegetable intake, body mass index), work-related factors (work demands, decision authority, skill discretion, physical job demands), and work engagement were assessed at baseline. At six-month follow-up, health, work ability, and sickness absence were assessed. Logistic regression analyses were performed to identify determinants of ill health, low work ability, and sickness absence. Additionally, additive interaction analyses were performed. Results A low work engagement at baseline was associated with ill health (OR: 2.02, 95% CI: 1.04-3.92) less than good work ability (OR: 3.51, 95% CI: 2.01-6.12), and sickness absence (short: OR: 1.51, 95% CI: 1.02-2.23, long: OR: 1.79, 95% CI: 0.99-3.24) at follow-up. A lack of vigorous physical activity (ORs 2.46-2.96) and obesity (ORs: 2.34-3.02) at baseline were associated with ill health, low work ability, and long-term sickness absence at follow-up. Frequently working in awkward postures (ORs: 4.85-5.25) was related with a low work ability and long-term sickness absence. Unhealthy lifestyle and unfavourable physical work-related factors were associated with a low work engagement at baseline. The interaction effects of lifestyle or work-related factors and work engagement on work ability were stronger than the sum of the single effects. Conclusion This study indicates that a low work engagement predicts ill health, a reduced work ability, and sickness absence. Furthermore, employees with an unhealthy lifestyle or unfavourable working conditions a low work engagement have a higher risk on a low work ability than their engaged colleagues. Hence, programs in occupational health should pay attention to both getting employees positively engaged in work and healthy in order to promote a productive work force. Results Among the most salient results, women worked mainly in the tertiary sector (78%), while men were distributed between the tertiary (44%) and primary sectors (37%). Over 70% of both women and men were not insured by their country's social security system. Among salaried workers, 24% of women and 20% of men had a written contract, approximately 13% of both had an oral contract and 3% had no contract. A...