Antiretroviral Therapy Discontinuation Common After Regimen Switch Despite Suppression

Switching antiretroviral therapy (ART) regimens was found to rarely result in virologic failure, discontinuation, or adverse effects, indicating discontinuations occurred for alternative reasons among patients with HIV infection who switched regimens. These study results were presented at IDWeek 2022, held from October 19 to 23, in Washington, DC.

Researchers conducted a cohort study to compare the efficacy of 3 different ART regimens among ART-experienced patients with HIV infection. Included patients were virologically suppressed (HIV viral load, <200 copies/mL) at enrollment. The researchers compared the real-world effectiveness of dolutegravir/lamivudine (DTG/3TC) — a 2-drug ART regimen — with bictegravir (BIC) and dolutegravir (DTG), both of which were 3-drug regimens. Cox proportional hazards regression and univariate Poisson regression models were used to determine the rate of virologic failure and regimen discontinuation. Virologic failure was defined as 2 or more viral load measurements equal to or greater than 200 copies/mL.

Among 8037 patients included in the analysis, 1450 switched to DTG/3TC, 5691 switched to BIC, and 896 switched to DTG. Of these 3 patient groups, 39%, 35%, and 35% were older than 50 years; 19%, 16%, and 18% were women; and 35%, 43%, and 49% were Black, respectively.

The incidence rate (IR) of virologic failure per 100 patient-years was evaluated among the 3 patient groups. The rate of virologic was highest among patients in the DTG group (IR, 1.78; 95% CI, 1.11-2.86), followed by those in the BIC (IR, 0.84; 95% CI, 0.66-1.09) and DTG/3TC (IR, 0.66; 95% CI, 0.35-1.23) groups.

The researchers also evaluated the rate of regimen discontinuations per 100 patient-years. Discontinuation incidence was highest among patients in the DTG/3TC group (IR, 17.69; 95% CI, 15.70-19.94), followed by those in the DTG (IR, 24.90; 95% CI, 21.94-28.26) and BIC (IR, 8.30; 95% CI, 7.66-8.99) groups. The rate of discontinuations due to adverse events was decreased among patients who received either DTG/3TC or DTG (3% vs 4%, respectively; P =.05) compared with those who received BIC (7%; P =.02). In all 3 groups, more than 50% of patients did not indicate a reason for ART discontinuation.

The risk for virologic failure and regimen discontinuation was assessed further after adjustments for baseline age, number of ART classes, sex, race/ethnicity, geographic location, core drug class of previous ART regimen, and CD4 cell count. Compared with patients who received DTG/3TC, there was a higher risk for virologic failure among patients who received DTG (adjusted hazard ratio [aHR], 5.21; 95% CI, 1.85-14.67) vs BIC (aHR, 1.39; 95% CI, 0.61-3.16). Compared with patients who received DTG/3TC, the risk for discontinuation was increased among those who received DTG (aHR, 1.69; 95% CI, 1.30-2.19) but decreased among those who received BIC (aHR, 0.51; 95% CI, 0.42-0.62).

Of patients who discontinued their regimen, virologic suppression was observed among 96%, 94%, and 93% of those in the DTG/3TC, BIC, and DTG groups, respectively, at the time of discontinuation. According to the researchers, “The most common reason for DTG 3DR [3-drug regimen] discontinuations was regimen simplification,” indicated by 21% of patients in the DTG group.

Based on these findings, “Most discontinuations were not attributed to the treatment (ie, loss of suppression, adverse diagnosis, side effects), suggesting other reasons for discontinuation despite high levels of suppression and tolerability,” the researchers concluded.