Differences in CD4 count increases in veterans starting antiretroviral therapy with lopinavir/ritonavir or efavirenz

Background

Efavirenz (EFV) and lopinavir/ritonavir (LPV/r) are both recommended as preferred backbone agents for combination antiretroviral therapy (cART) in treatment-naïve patients. Meta-analyses have suggested there is a difference in the magnitude of CD4 cell count response.

Methods

Within the virtual cohort of the VA clinical case registry (CCR), we used generalized linear models, accounting for multiple measurements within patients, to compare CD4 cell counts over a 48-month period following treatment initiation of either EFV- or LPV/r-containing cART (regardless of virologic response).

Summary of results

Between Sept. 1, 2000 and Dec. 31, 2006, 4,298 and 11,618 veterans started LPV/r- and EFV-containing cART, respectively. Only patients on continuous EFV or LPV/r therapy with no interruptions >60 days per pharmacy refill database were analyzed. There was no statistically significant difference in adherence or time on therapy between regimens. Baseline mean CD4 counts were 271 and 319, respectively (p < 0.001). Mean CD4 counts changes are presented in Table 1.

Table 1

Differences in CD4 changes were most pronounced for patients with low baseline CD4 count (<50 cells/μL): ΔCD4 was 303 vs. 206 cells at month 36; p = 0.0344.

Conclusion

Despite significantly lower baseline CD4 count, LPV/r-based regimens were associated with significantly greater CD4 gains at 6, 24, and 36 months compared with EFV-based regimens.