Risk factors for acute rheumatic fever: A case-control study.

Background: Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) remain an inequitable cause of avoidable suffering and early death in many countries, including among Indigenous Māori and Pacific populations in New Zealand. There is a lack of robust evidence on interventions to prevent ARF. This study aimed to identify modifiable risk factors, with the goal of producing evidence to support policies and programs to decrease rates of ARF.

Methods: A case-control study was undertaken in New Zealand using hospitalised, first episode ARF cases meeting a standard case-definition. Population controls (ratio of 3:1) were matched by age, ethnicity, socioeconomic deprivation, location, sex, and recruitment month. A comprehensive, pre-tested questionnaire was administered face-to-face by trained interviewers.

Findings: The study included 124 cases and 372 controls. Multivariable analysis identified strong associations between ARF and household crowding (OR 3·88; 95%CI 1·68-8·98) and barriers to accessing primary health care (OR 2·07; 95% CI 1·08-4·00), as well as a high intake of sugar-sweetened beverages (OR 2·00; 1·13-3·54). There was a marked five-fold higher ARF risk for those with a family history of ARF (OR 4·97; 95% CI 2·53-9·77). ARF risk was elevated following self-reported skin infection (aOR 2·53; 1·44-4·42) and sore throat (aOR 2·33; 1·49-3·62).

Interpretation: These globally relevant findings direct attention to the critical importance of household crowding and access to primary health care as strong modifiable causal factors in the development of ARF. They also support a greater focus on the role of managing skin infections in ARF prevention.

Funding: This research was funded by the Health Research Council of New Zealand (HRC) Rheumatic Fever Research Partnership (supported by the New Zealand Ministry of Health, Te Puni Kōkiri, Cure Kids, Heart Foundation, and HRC) award number 13/959.