Effectiveness of community mental health nursing on psychiatric hospitalisations in Switzerland: Mirror-image analysis

Background: Community Mental Health Nursing (CMHN) has gained importance in Switzerland as part of a broader shift toward community-based psychiatric care. While CMHN services are increasingly implemented, empirical evidence on their effectiveness in reducing psychiatric hospitalisations remains limited. This study aims to evaluate the effect of CMHN on psychiatric hospitalisations and to identify risk factors for hospitalisation during CMHN care.Methods: We conducted a naturalistic observational study using data from two linked national databases: the HomeCareData register and the Medical Statistics of hospitals. The study included adults who were admitted to CMHN services between January 2020 and December 2022 and whose data was documented in HomeCareData. With mirror-image methods we compared psychiatric hospitalisation rates in equally long pre-index and post-index periods, defined by each individual’s duration of CMHN care, with each participant serving as their own control. The start of CMHN care was defined as the index date. For a sensitivity analysis individuals hospitalized within 60 days before start of CMHN were excluded to address potential regression to the mean effects. Uni- and multivariable logistic regression were used to identify risk factors of hospitalisation during CMHN care.Results: The study sample comprised 5,252 individuals with a mean age of 52 years; 66% were female. The primary mirror-image analysis revealed a significant reduction in psychiatric hospitalisations following the start of CMHN (unadjusted Incidence Rate Ratio = 0.60; 95% Confidence Interval: 0.55–0.65). No significant effect was observed in the sensitivity analysis (unadjusted Incidence Rate Ratio = 0.97; 95% Confidence Interval: 0.87–1.09). Multivariable logistic regression identified previous psychiatric hospitalisations and compulsory admissions as significant risk factors of hospitalisation during CMHN care. Sociodemographic and diagnostic variables showed no significant associations.Conclusions: This is the first study to show a reduction of psychiatric hospitalisations after participation in CMHN services in Switzerland. However, this effect was not confirmed in the sensitivity analysis which may suggest a regression-to-the mean effect. The study demonstrates the feasibility of using linked routine data to evaluate real-world mental health interventions and underscores the need for broader data coverage and improved documentation to strengthen future research.