Use of boosted protease inhibitors reduces kaposi sarcoma incidence among male veterans with HIV infection

Background. Kaposi sarcoma (KS) incidence has decreased since combination antiretroviral therapy (cART). However, effects of cART type and duration on KS remain difficult to interpret secondary to KS-associated immune reconstitution inflammatory syndrome (IRIS). Methods. We performed a retrospective study of Veterans Affairs Human Immunodeficiency Virus Clinical Case Registry data from 1985 to 2010. We analyzed the relationship between cART regimens and KS using multivariable Poisson regression, stratified or adjusted for timing around cART initiation. KS was identified by ≤1 inpatient or ≤2 outpatient International Classification of Diseases, Ninth Revision codes (176.0-9). Percent of cART on specific regimen and total duration on specific regimen were examined. Results. There were 341 KS cases among 25 529 HIV-infected male veterans (incidence rate = 2.02/1000 person-years). Stratified by years after starting cART, every additional 10% time on boosted protease inhibitors (BPIs) was associated with reduced KS incidence in the third year of cART (incidence rate ratio [IRR] = 0.79; 95% confidence interval [CI],. 69-.90). Months on BPIs was associated with lower KS incidence (P =. 02). KS incidence was lower at 12-23 (IRR = 0.47; 95% CI,. 23-.95) and ≤36 (IRR = 0.14; 95% CI,. 02-1.00) months on BPIs compared with <6 months. Longer duration on other regimens was not associated with decreased KS incidence. Conclusions. Lower KS incidence was observed with longer BPI use, after accounting for potential IRIS and other factors. Future research should evaluate newer cART regimens and long-term benefits of PI-based cART on KS in other cohorts and prospective studies.