The scientific approach is to conduct a retrospective cohort study of patients with a claims diagnosis of HIV, AIDS, or ARC (simply referred to as HIV infection) among commercially insured people in the U.S. to estimate the IR of acute MI (AMI), AMI including coronary revascularization (CR) procedures, and CVD, comparing exposure to HAART treatments. We will identify a primary cohort of patients with an initial claims diagnosis of HIV infection occurring after at least 6 months of continuous enrollment in the Ingenix National Health Informatics (NHI) or Ingenix Impact National Managed Care (Impact) Databases between 01 January 1998 and 31 December 2007. For each eligible primary cohort member, we will identify all HAART dispensings during the baseline and follow-up periods and categorize person-time of exposure by any HAART, HAART class, and specific NRTI medications. We will also specifically evaluate the risk associated with fosamprenavir and amprenavir use. Study outcome events, including AMI, AMI including CR procedures, and CVD, will be identified from the medical claims data for all patients during the follow-up period.
For the primary analysis, we will estimate the absolute IR and 95% confidence intervals (CIs) of each study outcome event during periods of recent, past, non-use, and cumulative duration (non-use, \< 1 year, 1 - 2 years, and \> 2 years) of each HAART exposure classification. We will also estimate the rate difference (RD) and 95% CI of each study outcome event during periods of recent, past, and cumulative duration (\< 1 year, 1 - 2 years, and \> 2 years) of each HAART exposure classification relative to non-use. We will use Poisson regression models to estimate the multivariable adjusted rate ratio (RR) and 95% CIs of each study outcome event during periods of recent, past, and cumulative duration (non-use, \< 1 year, 1 - 2 years, and \> 2 years) of HAART use relative to non-use for each HAART exposure classification, adjusting for confounding variables derived from the claims history of each person during their 6-month baseline period to account for channeling bias and during the follow-up period to account for changing risk factors for CVD. To further account for confounding of indication by abacavir use, analyses will be stratified by calendar year 2004, during which time there was a significant change in the primary indication for abacavir use in HIV. Analyses will be repeated as a secondary analysis on the subgroup of patients in the NHI Database with any outpatient laboratory test result; these analyses will account for values of cholesterol, cluster of differentiation 4 (CD4) count, and viral load \[HIV-1 ribonucleic acid (RNA)\] laboratory tests.
Among the primary cohort, we will identify a subcohort of patients with an initial claims diagnosis of HIV infection occurring after at least 6 months of continuous enrollment and without HAART medication in the 6-month baseline period prior to the cohort entry date. We will repeat the primary and secondary analyses among this naïve subcohort of HAART initiators.
ViiV Healthcare is the new sponsor of this study, and GlaxoSmithKline is in the process of updating systems to reflect the change in sponsorship.
