Geographic variation in the utilisation of specialist healthcare for patients with severe mental illness in Norway: a population-based registry study.

The levels of geographic variations in the utilisation of outpatient and inpatient mental healthcare services among patients with severe mental illness are high. However, the geographic variation in total services provided by hospital catchment areas calculating the two service modalities together using their treatment cost ratio, is low. This may reflect the relatively equal performance of hospital catchment areas in terms of resource utilisation regardless which service modality they prioritise. Factors contributing to high geographic variation in individual service modalities need further investigation.