Objectives: To estimate the 3-year risk of myocardial infarction (MI) among participants in the Data Collection on Adverse Events of Anti-HIV Drugs (DAD) study.
Methods: Conventional cardiovascular risk equations were applied to baseline data from the DAD study to estimate the 3-year risk of MI. Best estimates were obtained by simply applying the risk equations, with upper and lower limits based on worst case and optimistic case scenarios. Three-year risks of AIDS or death were also estimated based on a prognostic scoring system for patients receiving antiretroviral (ARV) treatment, and on estimated AIDS rates in untreated people with HIV for those patients not on ARVs or if they were to cease ARVs.
Results: Analyses were based on 17 600 patients (24.3% female) recruited into the DAD study with baseline data and no previous MI. The overall 3-year risk of MI was estimated to be 0.72% (lower limit 0.35, upper limit 1.12%), corresponding to a total predicted 127 (65-197) MIs over a 3-year follow-up period. The risk was much greater for men than women (0.92% vs. 0.07%), with only three (2-8) MIs predicted in women. The 3-year risk of MI was estimated to increase from 0.30% (0.20-0.38%) in ARV naive patients to 1.07% (0.43-1.77%) in patients receiving ARVs from all three drug classes. The estimated 3-year risk of AIDS or death was in the range 6.2% to 11.1% in patients receiving ARVs if they continued treatment, and 22.5% to 29.4% if they ceased ARVs.
Discussion: These models suggest that although the increase in relative risk of MI as a result of ARV treatment may be as high as threefold in a worst case scenario, the absolute risk is modest with a best estimate of 3-year risk less than or equal to 1% in all groups of patients, and is outweighed by the benefits of ARV treatment in terms of reduced risk of AIDS and death in most patients. As estimates are based on models not validated for people receiving ARV drugs, all estimates should be interpreted cautiously.