Studying the Mental Health of a Nation: A Preliminary Report on a Population Survey in Singapore

Abstract

Aim: A Singapore Mental Health Survey was designed to study the prevalence and pattern of psychiatric morbidity of the general population. Community surveys reveal the true pattern of mental disorders, free from any self-selection into, or referral within the health care system. Methods: A cross-sectional survey design was used to estimate the point prevalence of minor psychiatric morbidity (MPM) in an areaprobability sample drawn from different regions. Disproportionate quota sampling yielded approximately equal numbers of Chinese, Malays and Indians for inter-ethnic comparison. The General Health Questionnaire, 28-item version (GHQ-28) measured psychoemotional symptoms in 3,020 subjects aged between 13-65 years. The GHQ-28 was validated against ICD-10 psychiatric diagnoses derived from structured psychiatric interview with the Composite International Diagnostic Interview (CIDI). Results: The optimal cut-off point for the GHQ-28 was determined to be 4/5 for Chinese, and 5/6 for Malays and Indians. Using the validated ethnic-specific cut-offs, MPM rate for Chinese was 17.4%, Malays 15.1% and Indians 17.8%. The population MPM prevalence rate was estimated to be 16.6% after standardisation with population census data. Specific types of ICD-10 psychiatric disorders which give rise to MPM were mainly anxiety and depressive disorders. Twelve percent of individuals with MPM had at least one ICD-10 disorder in the previous year. Conclusion: Two-staged methodology is an efficient, cost-effective approach to study population prevalence of mental illness. Screening instruments utilised should be validated specifically for the culture and setting. Information from population surveys of psychiatric morbidity are important for the planning of mental health services for the country.