Psychosis and suicide risk by ethnic origin and history of migration in the Netherlands

Background: There is an increased incidence of non-affective psychotic disorders (NAPD) among first- and second-generation migrants in Europe. The purpose of this population-based study was to compare the risk of suicide in Dutch natives and immigrants with or without NAPD. Methods: Cases of NAPD (n=12 580) from three Dutch psychiatric registers were linked to the cause of death register of Statistics Netherlands and were compared to matched controls (n=244 792) from the population register, who had no such diagnosis. Hazard ratios (HRs) of suicide were estimated and adjusted for age and gender by Cox regression analysis. Results: The presence of NAPD was strongly associated with suicide risk in each ethnic group. However, for all ethnic minority groups the HRs were somewhat lower than among Dutch natives, for whom the HR was 23.4 (95%-CI; 18.5-29.7). A closer examination revealed that suicide risk was influenced by the history of migration. While the risk for immigrants of the first generation, diagnosed with NAPD, was significantly lower than that for native Dutch patients (HR=0.45; 95%-CI: 0.28-0.73), the risk for those of the second generation was more similar to that for the Dutch (HR=0.85; 95%-CI: 0.51-1.40) (P value of history of migration=0.005). Conclusion: Immigrants diagnosed with NAPD of the first generation appear to be protected against suicide, whereas this protection is waning among those of the second generation. This is the first study worldwide on suicide in migrants with NAPD and the first study of suicide in patients with NAPD in the Netherlands.