de Dassel JL, et al. - Researchers used nested case–control and case–crossover designs as well as logistic regression to determine factors related to adherence (percent of doses administered), and the link between adherence and acute rheumatic fever (ARF) recurrence, progression to rheumatic heart disease, worsening or improvement of rheumatic heart disease, and mortality, by analyzing data from northern Australia. For the first time, it was shown in this study that increased adherence to penicillin prophylaxis led to attenuated ARF recurrence, and a possible mortality reduction. The factors that showed relation to higher adherence included being female, younger, having more-severe disease, and living remotely. A lower adherence was seen among those who misused alcohol. No decrease in the risk of ARF recurrence was seen until ≈40% of doses had been administered. A 4-fold increase in the odds of ARF recurrence was observed in association with receiving <80%, which also appeared to be associated with increased all-cause mortality.