The incidence of psychoses in diverse settings, INTREPID (2): a feasibility study in India, Nigeria, and Trinidad

Psychol Med. 2016 Jul;46(9):1923-33. doi: 10.1017/S0033291716000441. Epub 2016 Mar 28.


Background: There are striking global inequities in our knowledge of the incidence, aetiology, and outcome of psychotic disorders. For example, only around 10% of research on incidence of psychotic disorders originates in low- and middle-income countries. We established INTREPID I to develop, implement, and evaluate, in sites in India (Chengalpet), Nigeria (Ibadan), and Trinidad (Tunapuna-Piarco), methods for identifying and recruiting untreated cases of psychosis, as a basis for investigating incidence and, subsequently, risk factors, phenomenology, and outcome. In this paper, we compare case characteristics and incidence rates across the sites.

Method: In each site, to identify untreated cases of psychoses in defined catchment areas, we established case detection systems comprising mental health services, traditional and spiritual healers, and key informants.

Results: Rates of all untreated psychoses were 45.9 (per 1 00 000 person-years) in Chengalpet, 31.2 in Ibadan, and 36.9 in Tunapuna-Piarco. Duration of psychosis prior to detection was substantially longer in Chengalpet (median 232 weeks) than in Ibadan (median 13 weeks) and Tunapuna-Piarco (median 38 weeks). When analyses were restricted to cases with a short duration (i.e. onset within preceding 2 years) only, rates were 15.5 in Chengalpet, 29.1 in Ibadan, and 26.5 in Tunapuna-Piarco. Further, there was evidence of age and sex differences across sites, with an older average age of onset in Chengalpet and higher rates among women in Ibadan.

Conclusion: Our findings suggest there may be differences in rates of psychoses and in the clinical and demographic profiles of cases across economically and socially distinct settings.

Keywords: Epidemiology; India; Nigeria; Trinidad; incidence; psychoses.

MeSH terms

  • Adolescent
  • Adult
  • Catchment Area, Health
  • Epidemiologic Studies
  • Epidemiological Monitoring
  • Feasibility Studies
  • Female
  • Humans
  • Incidence
  • India / epidemiology
  • Male
  • Middle Aged
  • Nigeria / epidemiology
  • Psychotic Disorders / epidemiology*
  • Psychotic Disorders / physiopathology*
  • Schizophrenia / epidemiology*
  • Schizophrenia / physiopathology*
  • Trinidad and Tobago / epidemiology
  • Young Adult