PREVALENCE OF ASTHMA AND RISK-FACTORS AMONG CHINESE, MALAY, AND INDIAN ADULTS IN SINGAPORE

Background - The prevalence and morbidity of asthma vary greatly among different ethnic communities and geographical locations, but the role s of environmental and genetic factors are not fully understood. The d ifferences in prevalence of adult asthma among Chinese, Malay, and Ind ian ethnic groups in Singapore were examined, and the extent to which these could be explained by personal and environmental factors were in vestigated. Methods - A stratified disproportionate random sample (n = 2868) of Chinese (n = 1018), Malays (n = 967), and Indians (n = 883) of both sexes was drawn from households in five public housing estates , and an interviewer administered questionnaire was used to determine cumulative and current prevalence of ''physician diagnosed asthma'' (s ymptoms with a physician diagnosis of asthma). Results - Lifetime cumu lative prevalence (standardised to the general population) of ''physic ian diagnosed asthma'' was 4.7% in men and 4.3% in women; 12 month per iod prevalences were 2.4% and 2.0%, respectively. Cumulative prevalenc e of asthma was significantly higher in Indians (6.6%) and Malays (6.0 %) than in Chinese (3.0%); period prevalences of asthma were 4.5% in I ndians, 3.3% in Malays, and 0.9% in Chinese. Ownership of cats or dogs was more frequent in Malays (15.4%) and Indians (11.2%) than in Chine se (8.8%). Rugs and carpets were also more frequently used by Malays ( 52.2%) and Indians (40.7%) than by Chinese (8.9%). Current smoking pre valences were higher in Malays (27.3%) than in Indians (19.4%) and Chi nese (23.0%). Malays and Indians did not have higher rates of atopy (1 1.1% and 15.2%, respectively) than Chinese (15.4%). Adjustment for the se factors in multivariate analyses reduced the greater odds of asthma in Malays and Indians, but not to a significant extent. Conclusions - There are ethnic differences in the prevalence of asthma in Singapore which are not explained by differences in atopy, or other risk factor s. Other unmeasured environmental factors or genetic influences are li kely to account for residual differences in the prevalence of asthma.