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.