Comparison of single and boosted protease inhibitor versus nonnucleoside reverse transcriptase inhibitor-containing cART regimens in antiretroviral-naïve patients starting cART after January 1, 2000

BACKGROUND: Few published studies have considered both the short- and long-term virologic or immunologic response to combination antiretroviral therapy (cART) and the impact of different cART strategies. PURPOSE: To compare time to initial virologic (<500 copies/mL) or immunologic (>200/mm3 cell increase) response in antiretroviral-naïve patients starting either a single protease inhibitor (PI; n = 183), a ritonavir-boosted PI regimen (n = 197), or a nonnucleoside reverse transcriptase inhibitor (NNRTI)-based cART regimen (n = 447) after January 1, 2000, and the odds of lack of virologic or immunologic response at 3 years after starting cART. METHOD: Cox proportional hazards models and logistic regression. RESULTS: After adjustment, compared to patients taking an NNRTI-regimen, patients taking a single-PI regimen were significantly less likely to achieve a viral load (VL) <500 copies/mL (relative hazard [RH] 0.74, 95% CI 0.54-0.84, p = .0005); there was no difference between the boosted-PI regimen and the NNRTI regimen (p = .72). There were no differences between regimens in the risk of >200/mm3 CD4 cell increase after starting cART (p > .3). At 3 years after starting cART, patients taking a single-PI-based regimen were more likely to not have virologic suppression (<500 copies/mL; odds ratio [OR] 1.60, 95% CI 1.06-2.40, p = .024), while there were no differences in the odds of having an immunologic response (>200/mm3 increase; p > .15). This model was adjusted for CD4 and VL at starting cART, age, prior AIDS diagnosis, year of starting cART, and region of Europe. CONCLUSION: Compared to patients starting an NNRTI-based regimen, patients starting a single-PI regimen were less likely to be virologically suppressed at 3 years after starting cART. These results should be interpreted with caution, because of the potential biases associated with observational studies. Ultimately, clinical outcomes, such as new AIDS diagnoses or deaths, will be the measure of efficacy of cART regimens, which requires the follow-up of a very large number of patients over many years.