Background/Purpose: Acute Rheumatic Fever (ARF) and Rheumatic Heart Disease (RHD) remain major public health problems in the South Pacific. Triggering by group A beta hemolytic streptococcal (GAS) skin infection has been suspected but little documented1. Very high incidences of ARF (106/100 000) and cutaneous infections have been reported in the Loyalty islands (New Caledonia), where health care of the 20,000 Melanesian inhabitants is centralized in a few locations and provides an extensive electronic database since 1998, and systematic screening for RHD is regularly performed.

The aims of the study was to explore the link between ARF, RHD and skin infections by a retrospective case-control study.

Methods: The study was approved by the New Caledonian committee of Ethics and dealt with patients aged 6 to 26 years, seen from 1998 to 2018. Cases were ARF and/or RHD. Definite ARF was diagnosed according to the Jones criteria2; additional cases with strong clinical suspicion were also included as probable cases. RHD was diagnosed by cardiac ultrasound scan allowing definite and borderline diagnosis2. Sore throat and presumed streptococcal cutaneous infections were diagnosed by an algorithm, previously validated on a sample of 3000 events by an experimented clinician, which identified specific medical terms and ICD-10 codes in the electronic medical records. Each case was matched with 3 controls (without ARF and RHD) of same age, sex and living location. Infections were retrieved from the electronic medical records during the month, 6 months, one year, 5 years preceding the date of the first ARF/RHD diagnosis, for each case with the same index date for its matched control, and since birth. Numbers of infections per these time intervals were compared between cases and controls by univariate and multivariate conditional regression analysis in the total study population and its various subcategories (definite or probable ARF, definite or borderline RHD).

Results: 311 cases of ARF and RHD including 206 definite cases were identified. Polyarthralgias (48%) were the main clinical presentation. Marginal erythema was not seen and Sydenham chorea was rare (6.8%). Mean age of diagnosis was 10.6 ±3.8 years. Skin infection episodes were 3 to 4 times more frequent than sore throats in all studied time-intervals.

Multivariate analysis showed an increased exposure to skin infections and sore throats in the year preceding ARF/RHD diagnosis in the whole population of cases as compared to controls ( OR 2.18, 95% CI 1.46, 3.26) and 1.54, 95% CI 1.01, 2.36] respectively); skin infections (but not sore throat) were also increased the 206 definite cases (OR 1.34, 95% CI 1.01, 1.80) and in the 220 definite and probable ARF (OR 1.47, 95% CI 1.11, 1.94). In addition we observed a correlation between the seasonality of ARF and skin infections, which were both more frequent during the rainy season, and an overlap of areas with high incidence of ARF and areas with high incidence of skin infections.

Conclusion: Our results support the hypothesis that GAS skin infections play a role in the pathophysiology of ARF/RHD. In view of these results, there is an urgent need to implement preventive measures to reduce the incidence of skin infections in the Loyalty Islands.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rheumatic-fever-and-streptococcal-cutaneous-infection-a-case-control-study-in-the-loyalty-islands-new-caledonia/