Process Evaluation of a Problem-Solving Intervention with Workplace Involvement for Employees on Sickness Absence Due to Common Mental Disorders in Swedish Primary Health Care

PURPOSE: This process evaluation examined the implementation of a problem-solving intervention with workplace involvement (PSI-WPI) for employees with common mental disorders, developed to reduce sickness absence. The aim was to understand factors influencing the "problem-solving in primary care" (PROSA) effect evaluation, which showed no significant difference in sickness absence days between PSI-WPI and care-as-usual (CAU). METHODS: PSI-WPI included a five-step process typically delivered over three sessions by primary care rehabilitation coordinators. Process outcomes assessed were reach, dose delivered, dose received, fidelity and dose response. Data came from questionnaires, medical records, and registry data. Kruskal-Wallis tests assessed associations between number of PSI-WPI sessions and sickness absence days. A post hoc analysis explored characteristics of employees receiving no, one or ≥ three PSI-WPI sessions. RESULTS: PSI-WPI coordinators reported slightly more face-to-face sessions and three-part meetings, whereas CAU coordinators reported more telephone sessions. Coordinator support was received by 85% of PSI-WPI participants compared to 43% of CAU; 41% PSI-WPI participants received ≥ three sessions. Employees receiving ≥ three sessions had significantly more sickness absence days during 18-months follow-up than those receiving none. CONCLUSION: The intervention was largely delivered as intended and supported by sufficient training and resources. Dose-response findings suggest the intervention was primarily delivered to employees with more complex needs, highlighting the importance of accounting for preintervention sickness absence and targeting support. Future studies should strengthen implementation planning, refine theoretical assumptions, and ensure alignment between intervention design and participant needs, particularly when adapting return-to-work interventions from occupational health services to primary health care. TRIALS REGISTRATION NUMBER: The trial was registered at ClinicalTrials.gov, identifier: NCT03346395 on January 12th, 2018.