Compromising comprehensive AIDS management will lead to failure

Resistance profiles after different periods of exposure to a first-line antiretroviral regimen in a Cameroonian cohort of HIV type-1-infected patients

Background

The lack of HIV type-1 (HIV-1) viral load (VL) monitoring in resource-limited settings might favour the accumulation of resistance mutations and thus hamper second-line treatment efficacy. We investigated the factors associated with resistance after the initiation of antiretroviral therapy (ART) in the absence of virological monitoring.

Methods

Cross-sectional VL sampling of HIV-1-infected patients receiving first-line ART (nevirapine or efavirenz plus stavudine or zidovudine plus lamivudine) was carried out; those with a detectable VL were genotyped.

Results

Of the 573 patients undergoing VL sampling, 84 were genotyped. The mean number of nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) mutations increased with the duration of ART exposure ( P=0.02). Multivariable analysis showed that patients with a CD4+ T-cell count ≤50 cells/ mm3 at ART initiation (baseline) had a higher mean number of both NRTI and non-NRTI (NNRTI) mutations than those with a baseline CD4+ T-cell count >50 cells/mm3 (2.10 versus 0.56; P<0.0001; and 1.65 versus 0.76; P=0.005, respectively). A baseline CD4+ T-cell count ≤50 cells/mm3 predicted ≥1 NRTI mutation (adjusted odds ratio [AOR] 7.49, 95% confidence interval [CI] 2.20-32.14), ≥1 NNRTI mutation (AOR 4.25, 95% CI 1.36-15.48), ≥1 thymidine analogue mutation (AOR 8.45, 95% CI 2.16-40.16) and resistance to didanosine (AOR 6.36, 95% CI 1.49-32.29) and etravirine (AOR 4.72, 95% CI 1.53-15.70).

Conclusions

Without VL monitoring, the risk of drug resistance increases with the duration of ART and is associated with lower CD4+ T-cell counts at ART initiation. These data might help define strategies to preserve second-line treatment options in resource-limited settings.

Conservation of First-Line Antiretroviral Treatment Regimen where Therapeutic Options are Limited

Objectives

To determine rates and causes of switching from first- to second-line antiretroviral treatment (ART) regimens in a large treatment-naive cohort (a South African community-based ART service) where a targeted adherence intervention was used to manage initial virological breakthrough.

Methods

ART-naive adults ( n=929) commencing first-line non-nucleoside-based ART [according to WHO (2002) guidelines] between September 2002 and August 2005 were studied prospectively. Viral load (VL) and CD4+ T-cell counts were monitored every 4 months. All drug switches were recorded. Counsellor-driven adherence interventions were targeted to patients with a VL >1,000 copies/ml at any visit (virological breakthrough) and the VL measurement was repeated within 8 weeks. Two consecutive VL measurements >1,000 copies/ml was considered virological failure, triggering change to a second-line regimen.

Results

During 760 person-years of observation [median IQR) 189 (85–441) days], 823 (89%) patients were retained on ART, 2% transferred elsewhere, 7% died and 3% were lost to follow-up. A total of 893 (96%) patients remained on first-line therapy and 16 (1.7%) switched to second-line due to hypersensitivity reactions ( n=9) or lactic acidosis ( n=7). A Kaplan-Meier estimate for switching to second-line due to toxicity was 3.0% at 32 months. Virological breakthrough occurred in 67 (7.2%) patients, but, following use of a targeted adherence intervention, virological failure was confirmed in just 20 (2.2%). Kaplan-Meier estimates at 32 months were 20% for virological breakthrough but only 5.6% for confirmed virological failure.

Conclusion

Regimen switches were due to virological failure or toxicity. Although follow-up time was limited, over 95% of individuals remained on first-line ART using a combination of viral monitoring and a targeted adherence intervention.