Generalised anxiety disorder in Singapore: prevalence, co-morbidity and risk factors in a multi-ethnic population

There has been a relative lack of epidemiological data on generalised anxiety disorder (GAD) in Southeast Asia. A previous study reported a lifetime prevalence of 1.5% and highlighted low preference for seeking professional help and consultation by persons suspected to be suffering from mental health problems. The present study is part of a National Mental Health survey of adults conducted from February 2003-March 2004 specifically assessing anxiety and depression in Singapore. In this paper we report on prevalence, co-morbidity and risk factors associated with GAD.

We interviewed 2,847 households from an ethnically stratified random sample of adults aged 20-59 years who were Singapore citizens or permanent residents. The General Health Questionnaire and Schedule for Clinical Assessment of Neuropsychiatry were administered, which generated Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnoses of GAD. We assessed socio-demographic correlates, life events, medical and other psychiatric co-morbidities related to GAD.

Lifetime prevalence of GAD was 3.3%, current prevalence is 3.0%. Female to male ratio is 3.6:1. GAD was significantly associated (p<0.001) with the presence of other psychiatric co-morbidities, including major depressive disorder, dysthymia, panic disorder, agoraphobia and social phobia. Prevalence increased in older individuals, with the odds of association greatest in subjects with three or more co-morbid medical conditions [adjusted odds ratio (OR) 3.66]. Those who had experienced one or more threatening life events showed increased odds of association with GAD. Chinese ethnicity, the divorced and persons from both the upper and the lowest socio-economic status had highest odds of association with GAD.

We challenge established notions that GAD tends to be a disorder of the socially disadvantaged. Life events are important as precipitating factors in GAD, and uniquely different types of events appear to affect both extremes of social classes. High co-morbidity associations with current GAD are grounds for concern. This may suggest failure to seek treatment, hence giving rise to an increase in severity of the primary condition.