Sarcoidosis in Singapore: epidemiology, clinical presentation and ethnic differences

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.

A review of hospital medical records from June 1998 to May 2004 to identify patients with sarcoidosis.

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 asymptomatic (57.9%, P = 0.015) and less likely to have impaired spirometry (P = 0.013). Pulmonary sarcoid presented largely as stage 0 or stage 1 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.

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.