The chance of a person receiving involuntary care likely reflects a complex interplay between factors relating to the individual, their illness and the provider or episode of care.

We report an exploratory analysis factors associated with involuntary admission in a large sample of more than 166 000 admissions, of which 54% were involuntary, more than any primary study reported in the most recent meta-analysis.¹⁰

The strongest associations in our data were psychosis and organic mental health diagnoses, and being brought to hospital via legal means, likely reflecting the requirements of the NSW Mental Health Act.

However, demographic and episode-of-care factors, including those related to country of birth, socioeconomic status and marriage and insurance status, also contributed independently to involuntary status in our findings. The data suggests that non-clinical factors contribute to the decision to impose involuntary care, and that involuntary treatment might be imposed disproportionately on some groups, including people born overseas or with indicators of social disadvantage. There are numerous pathways by which these outcomes might be generated, including those related to the person, such as their trust in and willingness to engage with healthcare systems; those related to the clinician, including their assessments of the patient's function and safety in the community; and the service, including culturally appropriate treatment options.

Our findings are consistent with a previous large study of involuntary treatment in Ontario, Canada, which found that involuntary care was more common in people experiencing acute psychosis along with extreme agitation or suicidal ideation, as well as with recent police contact, although the strength of these associations was weaker than that found in our study.¹⁶

Large-scale ecological analyses of UK data^5,17 have found that involuntary treatment was more common in areas with high levels of deprivation. A recent meta-analysis found that male gender, single marital status, unemployment, receiving welfare benefits, being diagnosed with a psychotic disorder or bipolar disorder and previous involuntary hospital admission all had moderate associations with involuntary care.¹⁰ However, many studies have limited sample sizes and high risk of bias.¹⁰

Our study adds to meta-analytic evidence because meta-regression of study level data cannot easily explore interaction or covariation between variables in individuals. Where similar factors were available for our analysis, the results are broadly consistent; although our analysis found homelessness associated with voluntary, rather than involuntary status, which may reflect our large data-set being able to control for collinearity with other factors such as socioeconomic status.

The finding that gender has only a weak effect on involuntary status in our final model is also unexpected. Our study included measures of diagnosis, aggression, comorbidity and disability: a lack of association with gender after controlling for these factors may suggest that these variables may mediate the greater risk of involuntary care in males.

The association between race and involuntary treatment has received much attention, with migrants often found to be at greater risk of involuntarily treatment than locally born people.¹⁸ A systematic review found that Black Caribbean, Black African and South Asian people had a moderately increased risk of involuntary hospital admission compared with people of White ethnicity;¹⁸ however, that review some included studies that may be confounded by not controlling for differences in diagnosis between groups. We found that speaking a language other than English or being born overseas was weakly associated with an increased likelihood of involuntary treatment, but not for patients born in primarily English-speaking countries (the UK, Ireland, the USA or Canada).

Debate remains as to the cause for the increased rate of detentions among Black and minority ethnic groups, and whether it is confounded by relatively higher rates of psychotic illnesses^19,20 or by lower rates of voluntary treatment. Our finding that involuntary status was not uniformly more likely among people born overseas suggests that the issue is not simply related to the act of migration. These findings persisted after adjusting for diagnosis, clinical severity and comorbidity, although the effect size was weaker than that found in the recent meta-analysis.¹⁸ It is notable that Australia has a much higher proportion of overseas-born people in its population than the many countries in which the issue of involuntary status and race has been examined.²¹