March 24, 2014
A poster at CROI 2014, presented by Caroline Sabin from University College London and colleagues, presented follow-up results from D:A:D since the initial findings in 2008 of a link between abacavir use and risk of myocardial infarction (MI) in people with high cardiovascular risk.1
Given the high profile given to the initial results, abacavir should have been less likely to be prescribed in high CVD risk patients, with any confounding bias now working against seeing a continued association.
UK guidelines no longer recommend using abacavir in HIV positive people who have a high risk of cardiovascular disease (CVD), defined as >20% 10-year Framingham score.2 This is based on results from cohort studies that have reported an association, the largest of these being the prospective D:A:D study that was designed to look at ARVs and CVD and that first reported this associated at CROI in 2008.3
In this study, logistic regression models were used to compare CVD and abacavir use before and after March 2008.
When stratifying abacavir use, people at moderate or high CVD risk were more likely to use abacavir before March 2008 (aOR 1.14; 95%CI: 0.90, 1.44) and less likely to use it afterwards (aOR 0.74; 95%CI: 0.48, 1.13), p=0.007 for interaction. After March 2008, people at moderate/high CVD risk on abacavir were more likely to discontinue abacavir than those at low/unknown CVD risk (relative rate (RR) 1.49 [95% CI 1.34-1.65]).
In the new analysis, the rate of MI with current use of abacavir was 0.47 (95%CI: 0.42-0.52) compared to 0.21 (95%CI: 0.19-0.22) without, with abacavir associated with a 98% increase in MI (RR 1.98; 95%CI: 1.72-2.29). There was no difference in the early and late periods and results were unchanged after adjusting for other CVD-related factors.
It is notable that the D:A:D group took five years after the initial findings to accumulate sufficient new data to reassess this association.