Validity of police contacts as a performance indicator for the public mental health care system in Amsterdam: an open cohort study

The Public Mental Health Care (PMHC) system is a network of public services and care- and support institutions financed from public funds. Performance indicators based on the registration of police contacts could be a reliable and useful source of information for the stakeholders of the PMHC system to monitor performance. This study aimed to provide evidence on the validity of using police contacts as a performance indicator to assess the continuity of care in the PMHC system. Data on services received, police contacts and detention periods of 1928 people that entered the PMHC system in the city of Amsterdam were collected over a period of 51 months. Continuity of care was defined as receiving more than 90 days of uninterrupted service. The associations between police contacts and continuity were analyzed with multilevel Poisson and multivariate linear regression modeling. Clients had on average 2.12 police contacts per person-year. Clients with police contacts were younger, more often single, male, and more often diagnosed with psychiatric or substance abuse disorders than clients without police contacts. Incidence rates of police contacts were significantly lower for clients receiving continuous care than for clients receiving discontinuous care. The number of police contacts of clients receiving PMHC coordination per month was found to be a significant predictor of the percentage of clients in continuous care. The number of police contacts of clients can be used as a performance indicator for an urban PMHC system to evaluate the continuity of care in the PMHC system.