Co-occurring homelessness, justice involvement, opioid dependence and psychosis: a cross-sectoral data linkage study.

Background: Administrative data offer unique opportunities for researching experiences which pose barriers to participation in primary research and household surveys. Experiencing multiple social disadvantages is associated with very poor health outcomes, but little is known about how often this occurs and what combinations are most common. We linked administrative data across public services to create a novel population cohort containing information on experiences of homelessness, justice involvement, opioid dependence and psychosis.

Methods: We securely linked administrative data from (i) a population register derived from general practitioner registrations; (ii) local authority homelessness applications; (iii) prison records; (iv) criminal justice social work reports; (v) community dispensing for opioid substitution therapy; and (vi) a psychosis clinical register, for people aged ≥18 years resident in Glasgow, Scotland between 01 April 2010 and 31 March 2014. We estimated period prevalence and compared demographic characteristics for different combinations.

Results: Of 536 653 individuals in the cohort, 28 112 (5.2%) had at least one of the experiences of interest during the study period and 5178 (1.0%) had more than one. Prevalence of individual experiences varied from 2.4% (homelessness) to 0.7% (psychosis). The proportion of people with multiple co-occurring experiences was highest for imprisonment (50%) and lowest for psychosis (14%). Most combinations showed a predominance of men living in the most deprived areas of Scotland.

Conclusions: Cross-sectoral record linkage to study multiple forms of social disadvantage showed that co-occurrence of these experiences was relatively common. Following this demonstration of feasibility, these methods offer opportunities for evaluating the health impacts of policy and service change.