Schizoaffective disorder and schizophrenia are common presentations to psychiatry services. Research to date has focussed on hypothesised biological differences between these two disorders. Little is known about possible variations in admission patterns. Our study compared demographic and clinical features of patients admitted voluntarily and involuntarily with diagnoses of schizoaffective disorder or schizophrenia to three psychiatry admission units in Ireland.

We studied all admissions to three acute psychiatry units in Ireland for periods between 1 January 2008 and 31 December 2018. We recorded demographic and clinical variables for all admissions. Voluntary and involuntary admissions of patients with schizoaffective disorder were compared to those with schizophrenia.

We studied 5581 admissions to the study units for varying periods between January 2008 and December 2018, covering a total of 1 976 154 person-years across the 3 catchment areas. The 3 study areas had 218.8, 145.5 and 411.2 admissions per 100 000 person-years, respectively. Of the 5581 admissions over the study periods, schizoaffective disorder accounted for 5% (n = 260) and schizophrenia for 17% (n = 949). Admissions with schizoaffective disorder were significantly more likely to be female and older, and less likely to have involuntary admission status, compared to those with schizophrenia. As first admissions were not distinguished from re-admissions in this dataset, these findings merit further study.

Admissions with a schizoaffective disorder differ significantly from those with schizophrenia, being, in particular, less likely to be involuntary admissions. This suggests that psychotic symptoms might be a stronger driver of involuntary psychiatry admission than affective symptoms.

Minority ethnic and migrant groups face an elevated risk of compulsory admission for mental illness. There are overlapping cultural, socio-demographic, and structural explanations for this risk that require further investigation.

By linking Swedish national register data, we established a cohort of persons first diagnosed with a psychotic disorder between 2001 and 2016. We used multilevel mixed-effects logistic modelling to investigate variation in compulsory admission at first diagnosis of psychosis across migrant and Swedish-born groups with individual and neighbourhood-level covariates.

Our cohort included 12 000 individuals, with 1298 (10.8%) admitted compulsorily. In an unadjusted model, being a migrant [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.26–1.73] or child of a migrant (OR 1.27; 95% CI 1.10–1.47) increased risk of compulsory admission. However after multivariable modelling, region-of-origin provided a better fit to the data than migrant status; excess risk of compulsory admission was elevated for individuals from sub-Saharan African (OR 1.94; 95% CI 1.51–2.49), Middle Eastern and North African (OR 1.46; 95% CI 1.17–1.81), non-Nordic European (OR 1.27; 95% CI 1.01–1.61), and mixed Swedish-Nordic backgrounds (OR 1.33; 95% CI 1.03–1.72). Risk of compulsory admission was greater in more densely populated neighbourhoods [OR per standard deviation (s.d.) increase in the exposure: 1.12, 95% CI 1.06–1.18], an effect that appeared to be driven by own-region migrant density (OR per s.d. increase in exposure: 1.12; 95% CI 1.02–1.24).

Inequalities in the risk of compulsory admission by migrant status, region-of-origin, urban living and own-region migrant density highlight discernible factors which raise barriers to equitable care and provide potential targets for intervention.