Secondary prophylaxis

Secondary prophylaxis with regular benzylbenzathine penicillin G (BPG) is the only rheumatic heart disease (RHD) control strategy shown to be both clinically and cost effective at community and individual levels (Webb 2015; Wyber & Carapetis 2015; RHD Australia 2020), and needs to be complemented with other primordial and primary prevention activities to eliminate RHD. According to the clinical guidelines in place when the data in this report were collected, the recommended regimen to prevent recurrences of acute rheumatic fever (ARF) and progression of RHD involves regular intramuscular injections of BPG every 21 or 28 days, for a minimum of 10 years (RHD Australia 2012). (For a cohort of individuals without cardiac involvement during an ARF episode, the 2020 guidelines now state a minimum of 5 years since the most recent ARF episode.) This treatment aims to provide penicillin in the blood over a period of 3 to 4 weeks, providing protection against Strep A infections (Wyber 2013). As the penicillin concentration wanes, the individual’s susceptibility to subsequent Strep A infection and to recurrent ARF will increase. 

Delivery of secondary prophylaxis to people prescribed 4-weekly BPG is 13 annual doses given no more than 28 days apart. If a dose is not given by the 28th day after the previous dose, the person becomes vulnerable to Strep A infection and recurrent ARF. The days between day 28 and the date of the next dose is given are referred to as ‘days at risk’. As the number of days at risk increases, the risk of recurrent ARF increases (de Dassel 2018). (People prescribed 3-weekly BPG should receive 17 doses no more than 21 days apart).

BPG is routinely recommended every 28 days to maintain prolonged, low-level benzylpenicillin concentrations. A 21-day antibiotic regimen may be considered by a medical specialist for a small proportion of patients who have breakthrough ARF despite receiving the 28-day regimen, or are at high risk of adverse consequences if ARF occurs (RHD Australia 2020).

Delivery of BPG every 21 or 28 days is challenging for health services, affected individuals and their families. In remote Indigenous communities, a major factor contributing to low levels of prophylaxis delivery is the availability and acceptability of health services. Personal factors such as injection refusal, pain caused by injections or a lack of knowledge and understanding of ARF and RHD may negatively influence adherence to secondary prophylaxis but are often not major contributing factors (Parnaby & Carapetis 2010).