Predicting postnatal mental disorder with a screening questionnaire: a prospective cohort study from Zimbabwe.

BACKGROUND: Postnatal mental disorders are common causes of morbidity but are rarely diagnosed or treated in busy primary care clinics in developing countries. OBJECTIVE: To determine whether a brief psychiatric screening questionnaire used in the 8th month of pregnancy can predict postnatal mental disorder. STUDY DESIGN: Prospective cohort study. SITE: A peri-urban settlement in Zimbabwe. POPULATION: 500 women in the 8th month of pregnancy identified by traditional birth attendants and primary care clinics. SAMPLE: "High risk" cohort consisted of all women who scored 8 or more on the Shona Symptom Questionnaire (SSQ), an indigenous psychiatric questionnaire (n = 95). Low risk cohort consisted of 105 women randomly selected from the remainder of the sampling frame. OUTCOME MEASURE: Revised Clinical Interview Schedule at six to eight weeks postpartum; scores of 14 or more indicate psychiatric caseness. RESULTS: The prevalence of postnatal mental illness was 16%. Odds ratios (95% confidence intervals) for high risk women becoming cases in the postnatal period were 10.6, 4.8, 23.9, p < 0.0001 after adjustment for age, marital status, and occupation. CONCLUSIONS: A brief method of detecting women at high risk of developing a postnatal mental disorder can be used with reasonable accuracy in the 8th month of pregnancy. Further research is needed to determine whether interventions applied to this high risk group can reduce their postnatal morbidity.