Sarcoidosis in Singapore: Epidemiology, clinical presentation and ethnic differences

Background and objectives: The aim of this study is to better understand the epidemiological and clinical features of patients with sarcoidosis in Singapore and to ascertain if ethnic differences exist. Methods: A review of hospital medical records from June 1998 to May 2004 to identify patients with sarcoidosis. Results: There were 59 patients with sarcoidosis identified (19 Chinese, 29 Asian Indian and 11 Malay). The estimated annual incidence of sarcoidosis in Singapore was 0.56 per 100 000. There was a significant difference between the observed and expected disease frequency in Chinese (32.2% vs 78.7%) and Indians (49.2% vs 6.0%, P < 0.005). A bimodal distribution of age at diagnosis was seen with peaks in the 30-39 years and 50-59 years age groups; 38.9% of cases were over the age of 50. Chinese patients were more likely to be asymptornatic (57.9%, P = 0.015) and less likely to have impaired spirometry (P= 0.013). Pulmonary sarcoid presented largely as stage 0 or stage I disease (74.4%). Overall mean spirometry was unimpaired and prognosis was good with 79.2% showing no radiological deterioration. There were no significant differences in organ involvement or treatment between ethnic groups. Conclusion: Sarcoidosis in Singapore is rare and the incidence differs between ethnic groups. Chinese appear to have a lower incidence and a less symptomatic presentation; Indians have a higher incidence and poorer clinical course.