Letter by Karthikeyan et al regarding article, "Acute rheumatic fever and rheumatic heart disease: incidence and progression in the Northern Territory of Australia, 1997 to 2010".

BACKGROUND Although acute rheumatic fever (ARF) and its sequel, rheumatic heart disease (RHD), continue to cause a large burden of morbidity and mortality in disadvantaged populations, most studies investigating the effectiveness of control programs date from the 1950s. A control program, including a disease register, in the Northern Territory of Australia where the Indigenous population has high rates of ARF and RHD allowed us to examine current disease incidence and progression. METHODS AND RESULTS ARF and RHD incidence rates, ARF recurrence rates, progression rates from ARF to RHD to heart failure, and RHD survival and mortality rates were calculated for Northern Territory residents from 1997 to 2010. For Indigenous people, ARF incidence was highest in the 5- to 14-year age group (males, 162 per 100,000; females, 228 per 100,000). There was little evidence that the incidence of ARF or RHD had declined. The ARF recurrence rate declined by 9% per year after diagnosis. After a first ARF diagnosis, 61% developed RHD within 10 years. After RHD diagnosis, 27% developed heart failure within 5 years. For Indigenous RHD patients, the relative survival rate was 88.4% at 10 years after diagnosis and the standardized mortality ratio was 1.56 (95% confidence interval, 1.23-1.96). CONCLUSIONS For Indigenous Australians in the Northern Territory, ARF and RHD incidence and associated mortality remain very high. The reduction in ARF recurrence indicates that the RHD control program has improved secondary prophylaxis; a decline in RHD incidence is expected to follow.