The comparative effectiveness of NRTI-sparing dual regimens in emulated trials using observational data from the Swiss HIV Cohort Study. Antiviral Therapy
Young et al. used data from the Swiss HIV Cohort Study to estimate the effectiveness of dolutegravir dual regimens relative to alternative NRTI-sparing dual regimens. For that, they emulated two trials by propensity score matching case patients on the dolutegravir regimen with control patients on an alternative regimen. They analysed the case control sets using Bayesian Cox model and estimated effectiveness as the percentage still on their trial regimen without virological failure at week 48.
The authors matched 58 cases treated with dolutegravir to 17 controls treated with boosted darunavir, both with lamivudine or emtricitabine. The estimated difference in effectiveness was 15% (95% credible interval [Crl] 2-33) and 12% (95% Crl 0-26) in two sequential analyses 1 year apart. In comparison of fully NRTI-sparing regimens, 54 cases treated with dolutegravir were matched to 32 controls treated with raltegravir (both with boosted darunavir). The estimated difference in effectiveness was 9% (95% Crl -1-21) and 5% (95% Crl -4-15) in the two sequential analyses.
In conclusion, the estimates of relative effectiveness suggest that at 48 weeks both dolutegravir regimens would be at worst 4% less effective than the alternatives – the non-inferiority margin recommended by the FDA for HIV switch trials. All four regimens seem suitable for patients needing an NRTI-sparing regimen: there were few virological failures and few treatment changes due to toxicity.