Antibiotic prophylaxis and incidence of endocarditis before and after the 2007 AHA recommendations

Background The American Heart Association updated its recommendations for antibiotic prophylaxis (AP) to prevent infective endocarditis (IE) in 2007, advising that AP cease for those at moderate risk of IE, but continue for those at high risk.

Objectives The authors sought to quantify any change in AP prescribing and IE incidence.

Methods High-risk, moderate-risk, and unknown/low-risk individuals with linked prescription and Medicare or commercial health care data were identified in the Truven Health MarketScan databases from May 2003 through August 2015 (198,522,665 enrollee-years of data). AP prescribing and IE incidence were evaluated by Poisson model analysis.

Results By August 2015, the 2007 recommendation change was associated with a significant 64% (95% confidence interval [CI]: 59% to 68%) estimated fall in AP prescribing for moderate-risk individuals and a 20% (95% CI: 4% to 32%) estimated fall for those at high risk. Over the same period, there was a barely significant 75% (95% CI: 3% to 200%) estimated increase in IE incidence among moderate-risk individuals and a significant 177% estimated increase (95% CI: 66% to 361%) among those at high risk. In unknown/low-risk individuals, there was a significant 52% (95% CI: 46% to 58%) estimated fall in AP prescribing, but no significant increase in IE incidence.

Conclusions AP prescribing fell among all IE risk groups, particularly those at moderate risk. Concurrently, there was a significant increase in IE incidence among high-risk individuals, a borderline significant increase in moderate-risk individuals, and no change for those at low/unknown risk. Although these data do not establish a cause–effect relationship between AP reduction and IE increase, the fall in AP prescribing in those at high risk is of concern and, coupled with the borderline increase in IE incidence among those at moderate risk, warrants further investigation.