Importance Determining whether migrants with nonaffective psychotic disorders (NAPDs) experience poorer outcomes after illness onset is essential to ensure adequate health care provision to these disadvantaged populations.

Objective To compare cumulative hospital days for NAPDs during the first 5 years of illness among refugee, nonrefugee, and second-generation migrants and their Swedish and Danish peers.

Design, Setting, and Participants This was a prospective cohort study of individuals treated for incident NAPDs in inpatient or outpatient settings between January 1, 2006, and December 31, 2013, and followed up for 5 years. This population-based study used Swedish and Danish national registries. Included participants were individuals in Sweden and Denmark, aged 18 to 35 years, treated for incident NAPDs. Data analyses were conducted from November 2022 to August 2023.

Exposures Population group (determined according to residency in either country, not both countries), categorized as refugee (migrants whose residence in Sweden or Denmark was registered as refugee status or family reunification with a refugee), nonrefugee (all other individuals born outside Sweden and Denmark), second generation (individuals born in Sweden or Denmark with at least 1 parent born abroad), or native born (individuals born in Sweden or Denmark with both parents born in these countries).

Main Outcome and Measures Total hospital days for NAPDs during the first 5 years of illness, analyzed using a hurdle model. Among those ever admitted, total number of admissions and mean admission length were examined.

Results In total, 7733 individuals in Sweden (mean [SD] age, 26.0 [5.1] years; 4919 male [63.6%]) and 8747 in Denmark (mean [SD] age 24.8 [5.0] years; 5324 male [60.9%]) were followed up for 5 years or until death or emigration. After adjusting for a range of sociodemographic and clinical factors, the odds of experiencing any hospital days for NAPD were significantly higher among migrant groups compared with their native-born peers (Sweden: second generation, odds ratio [OR], 1.17; 95% CI, 1.03-1.33; P = .01; nonrefugee migrant, OR, 1.45; 95% CI, 1.21-1.73; P < .001; refugee, OR, 1.25; 95% CI, 1.06-1.47; P = .009; Denmark: second generation, OR, 1.21; 95% CI, 1.05-1.40; P = .01; nonrefugee migrant, OR, 1.33; 95% CI, 1.14-1.55; P < .001). These odds were highest among nonrefugee (Sweden: OR, 2.53; 95% CI, 1.59-4.03; P < .001; Denmark: OR, 2.61; 95% CI, 1.70-4.01; P < .001) and refugee (Sweden: OR, 1.96; 95% CI, 1.43-2.69; P < .001; Denmark: OR, 2.14; 95% CI, 1.42-3.21; P < .001) migrants from Africa and those who had arrived within 3 to 5 years (Sweden: nonrefugee migrants, OR, 1.93; 95% CI, 1.26-2.95; P = .002; refugees, OR, 2.38; 95% CI, 1.46-3.88; P < .001; Denmark: nonrefugee migrants, OR, 1.66; 95% CI, 0.96-2.85; P = .07; refugees, OR, 3.40; 95% CI, 1.13-10.17; P = .03). Among those ever hospitalized, refugees in both countries (Sweden, incidence rate ratio [IRR], 1.30; 95% CI, 1.12-1.51; P < .001; Denmark, IRR, 1.47; 95% CI, 1.24-1.75; P < .001) and second-generation migrants in Denmark (IRR, 1.22; 95% CI, 1.07-1.39; P = .003) experienced more days hospitalized for NAPDs than native-born individuals.

Conclusions and Relevance In this prospective cohort study of individuals with NAPDs, results suggest that refugee, nonrefugee, and second-generation migrants experience more days hospitalized for these disorders than their native-born peers. Patterns were consistent across 2 countries with different models of psychosis care and immigration and integration policies.