Intervention adherence
RECRUITMENT
Among the two private and nine public intervention centres, the average proportion of enrolled patients that had a common mental health diagnosis in 2015 (the year the centres were recruited to the study) was 15% (range 13–18%). This was expected to provide a sound basis for patient recruitment. However, only five of the eleven intervention centres succeeded with protocol adherence. Together, RCs at these centres recruited 56 patients and successfully contacted 53 employers. In the six remaining centres, only 9 patients were recruited, and one employer contact was made. Post-intervention interviews with participant managers, RCs and GPs provide preliminary explanations for why centres failed or succeeded in their implementation. At the centres that succeeded, the RC had a clear role vis-à-vis the GPs, and routines for working with sickness certification and insurance medicine were well established before these centres engaged in the study. In other words, the compatibility between the intervention and pre-existing workflows was high. Second, centres that struggled with high workloads and staff turnover failed in their implementation. Here, both GPs and RCs were tasked with managing the daily operations, and their ‘readiness for change’ was low. However, these explanations should be explored further in future research.