Longitudinal trajectories of sickness absence among young adults with a history of depression and anxiety symptoms in Sweden

Background: Depression and anxiety are associated with increased risk of sickness absence (SA), yet the developmental patterns of SA remain unclear. We aimed to identify trajectories of SA in young adults with depression and/or anxiety, accounting for sociodemographic and occupational factors. Methods: Longitudinal study of 1445 twin individuals with elevated depressive/anxiety symptoms in late adolescence or young adulthood (age range: 19-30), assessed in Swedish surveys completed in 2005. Through linkage to nationwide registries, individuals were prospectively followed from 2006 to 2018. The outcome included consecutive annual days of SA, which were analyzed using group-based trajectory modeling. Multinomial logistic regression estimating odds ratios (OR) with 95 % confidence intervals (CI) was used to examine associations of age, sex, and educational level with the resulting SA trajectories. Results: Four distinct SA trajectories were identified in the total sample: 'high-increasing' (6 %), 'low-increasing' (12 %), 'high-decreasing' (13 %), and 'low-constant' (69 %). Increasing age was associated with higher odds of belonging to the low-increasing trajectory (OR = 1.07, 95 % CI = 1.02-1.12). Women had higher odds of belonging to the low-increasing trajectory (OR = 1.67, 95 % CI = 1.10-2.53), compared with men. Higher education was associated with lower odds of belonging to high-increasing (OR = 0.34, 95 % CI = 0.22-0.54) and high-decreasing (OR = 0.59, 95 % CI = 0.43-0.81) trajectories, compared with lower education. Few differences were observed in analyses stratified by occupational sector. Limitations: Information on potential confounders (e.g., psychiatric comorbidity, work-environment factors) was not available. Conclusions: Among young adults with prior depression/anxiety, close to every fifth showed rising SA trajectories over time. This calls for targeted strategies to improve public mental health already at young ages.