Lay summary
Acute rheumatic fever (ARF) is an immune-mediated inflammatory condition triggered by the bacterium group A streptococcus, affecting the joints and heart valves. In approximately 50% of cases, ARF leads to permanent heart damage known as rheumatic heart disease (RHD). Approximately 150 Māori and Pacific children suffer from ARF each year in New Zealand. Four-weekly intramuscular penicillin injections prevent relapses, but there is no proven treatment that effectively reduces heart damage. Hydroxychloroquine (HCQ) has been safely used for many decades to treat rheumatological conditions such as systemic lupus erythematosus. Recent studies have shown that HCQ reduces inflammation in the blood of ARF patients. In 2019, two New Zealand patients with severe ARF were treated with HCQ, both with favourable responses. This trial involves randomising approximately 150 New Zealand children with ARF to receive either HCQ or placebo for 6 weeks, to see if this reduces inflammation and early heart damage.