The scale-up of antiretroviral therapy (ART) in Kenya is being undermined by high rates of treatment failure, investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes. Over a third of patients failed first- and second-line therapy. Use of inappropriate regimens and lack of adherence support were associated with failure to control viral load.
“We describe factors that influence adherence and virologic failure, and provide evidence to inform treatment decisions under conditions of limiting resources,” comment the authors. “Of the 514 patients…35.9% failed first-line regimen…and 36% failed second-line after switching treatment.”
Access to ART is expanding rapidly in Kenya. Evidence from around the world shows that ART can transform the health and life expectancy of people with HIV. But there is concern that weaknesses in health systems, use of inappropriate regimens and restricted access to viral monitoring are undermining the potential benefits of HIV therapy in Kenya.
Investigators therefore designed a study to determine the proportion of people taking long-term ART who experienced virologic failure with first- and second-line regimens and the impact of factors such as adherence support and viral load monitoring on treatment outcomes.
People aged between 5 and 73 years were recruited at six rural treatment centres and had been taking ART for up to 228 months (median, 48 months). All the facilities provided community peer support programmes run by HIV-positive volunteers to support patients to adhere to their therapy. Treatment failure was defined as viral load persistently above 1000 copies/ml in consecutive viral load tests at least six months apart.
The most commonly used (36%) combination of anti-HIV drugs was zidovudine, lamivudine and nevirapine or efavirenz, followed by stavudine, lamivudine and nevirapine or efavirenz (35%), with the remaining 23% of patients treated with tenofovir, lamivudine and nevirapine or efavirenz.
Approximately 46% of patients were actively involved in adherence support programmes; 21% had partial involvement and a third were uninvolved.
Overall, 35.9% experienced virologic failure. Rates differed according to regimen and were significantly higher for patients taking stavudine compared to tenofovir (41% vs 29%, p = 0.043).
Adherence peer support and higher levels of adherence were both associated (p < 0.001) with virologic suppression. Viral load declined significantly with increasing engagement with peer support. Patients actively engaged in community peer support programmes had viral load that was nearly 20-times lower (1.87 log10 copies) than patients who never received peer support (3.13 log10 copies).
Adherence was rated as good (95% or above) for 83% of patients receiving peer support. This compared to 39% of those who had partial engagement in this service and 29% of those who never received peer support. Patients taking tenofovir were less likely to report poor adherence than those treated with either stavudine or zidovudine.
Only 17% of patients changed therapy. The median time to treatment switch was 32 months. Approximately three-quarters of those changing therapy were taking stavudine, much higher than the 14% and 10% switch rates observed among people taking zidovudine and tenofovir.
Individuals who changed therapy were no more likely to have experienced virologic failure as patients who remained on their first-line therapy, and both switchers and non-switchers had comparable viral load at the time of the treatment change. “Thus, patients may be switched unnecessarily to secondary treatment, while others fail to gain timely access to critical treatment decisions,” comment the investigators.
There was a 36% virologic failure rate among patients who changed to second-line therapy.
A single viral load test after six or twelve months of therapy detected virologic failure as effectively as two sequential tests.
“We have demonstrated high virologic treatment failure among Kenyan ART patients and shown that peer support enhances adherence to improve treatment outcome,” conclude the authors. They recommend that adherence support using trained HIV-positive volunteers should be expanded and use of ART regimens recommended by WHO.
Ochieny W et al. Correlates of adherence and treatment failure among Kenyan patients on long-term highly active anti-retroviral therapy. J Acquir Immune Defic Syndr, online edition. DOI: 10. 1097/QAI.0000000000000580 (2015).