Measuring the level of compulsory hospitalisation in mental health care: The performance of different measures across areas and over time

Objective A variety of measures are used for reporting levels of compulsory psychiatric hospitalisation. This complicates comparisons between studies and makes it hard to establish the extent of geographic variation. We aimed to investigate how measures based on events, individuals and duration portray geographical variation differently and perform over time, how they correlate and how well they predict future ranked levels of compulsory hospitalisation. Methods Small-area analysis, correlation analysis and linear regressions of data from a Norwegian health registry containing whole population data from 2014 to 2018. Results The average compulsory hospitalisation rate per 100,000 inhabitant was 5.6 times higher in the highest area, compared to the lowest, while the difference for the compulsory inpatient rate was 3.2. Population rates based on inpatients correlate strongly with rates of compulsory hospitalisations (r = 0.88) and duration (r = 0.78). 68%–81% of ranked compulsory hospitalisation rates could be explained by each area's rank the previous year. Conclusion There are stable differences in service delivery between catchment areas in Norway. In future research, multiple measures of the level of compulsory hospitalisation should ideally be included when investigating geographical variation. It is important that researchers describe accurately the measure upon which their results are based