Background Patients with severe mental disorder, like schizophrenia or bipolar disorders, need continuity of integrated healthcare to prevent crisis and hospitalization. Many of these patients discontinue their treatment, often experiencing adverse outcomes. The first objective of this study was to assess whether patients with schizophrenia or bipolar disorder receive continuity of psychiatric elective care. The second objective is to assess the relation between continuity of care with crisis and hospitalization. Methods Large registry-based retrospective cohorts of patients with schizophrenia or bipolar disorders were extracted from the registries of major Dutch healthinsurance companies over 2008-2014. The main research questions of six studies were: 1) Is the relation between continuity of care and hospitalization in the Netherlands changing from a period (2008-2011) with few financial barriers to receive psychiatric and somatic healthcare to a period (2012-2014) with a high rise in general co-payments, and a specific co-payment for psychiatric care in 2012 only? (studies 1-3) 2) What is the relation between route of administration of antipsychotic medication and time to discontinuation of psychiatric care? (study 4) 3) In patients treated for their disorder, can their previous psychiatric care predict discontinuity? Controlling for predictors of discontinuity, is there practice variation in continuity of care between providers of psychiatric care? (study 5-6) Major results 1) 60% of patients with schizophrenia or bipolar disorder receive continuity of care over 6 years 2) Continuity of care coincides with less crisis care, more elective care, more somatic care 3) The reduction in elective care over 2009-2014 is alarming 4) Somatic care increased 5) High co-payments coincide with less continuity of care and more crisis care 6) Crisis care was low under continuity of care and high in quarters with disorder specific medication only 7) High discontinuity in antipsychotic formulations: oral-weekly an alternative ...