WHO: HIV drug-resistance remains low

BOSTON — Global surveillance from 2002 to 2010 suggest that overall transmitted HIV drug-resistance remains low, but geographic areas where surveys show moderate transmitted HIV drug-resistance merit attention, according to a presenter here.

In acquired HIV drug-resistance surveys, drug-resistance prior to ART initiation was very low, suggesting efficacy of current first-line regimens.

“As ART is scaled-up, the development of HIV drug-resistance is inevitable,” Silvia Bertagnolio, MD of the WHO department of HIV/AIDS in Switzerland, told Infectious Disease News. “Routine, standardized, population-based surveillance of transmitted and acquired HIV drug-resistance is imperative to the success of global ART scale-up.”

Transmitted HIV drug resistance

Bertagnolio presented results from two surveys using the WHO HIV drug-resistance strategy.

In total, 41 surveys of transmission of HIV drug resistance (TDR) were conducted in recently infected populations, which were mostly represented by pregnant women aged younger than aged 24 years, across 41 geographic regions in 20 countries.

Of these surveys, 85% were conducted in African countries, 22% in Asia, and one in Mexico City. Prevalence of TDR was classified into one of the following categories:

Low prevalence: <5%
Moderate prevalence: between 5% and15%
High prevalence: >15%

The combined analysis from all surveys showed overall HIV drug resistance prevalence is 3.7% (95% CI; 2.86-4.54) in the 1,920 recently infected subjects.

Approximately 83% of the 41 surveys show low TDR, and 17% show moderate TDR. Moderate levels of TDR was shown in four surveys to non-nucleoside reverse transcriptase inhibitors (NNRTI) (Yaoundé, Lilongwe, Maputo, Ho Chi Min City), two surveys to nucleoside reverse transcriptase inhibitors (NRTI) (Mexico City, Douala) and one survey to both NNRTI and NRTI (Ouagadougou).

“ART clinic and program factors in areas with reported moderate rates of TDR should be investigated to assess their potential contributions to the emergence and transmission of drug-resistant HIV,” she said. “However, at this stage, no treatment guidelines changes are warranted before further investigations. Available HIV drug-resistance data suggest that currently available first-line regimens are appropriate for the majority of the population.”

Acquired HIV drug resistance

For surveillance of acquired HIV drug-resistance (ADR) in populations on ART, 15 surveys were conducted in 15 clinics across India, Mozambique, Malawi, Burundi and Nigeria.

Of 2,150 patients initiating ART at 15 clinics (naive and ARV-exposed) 6% show HIV drug-resistance to any drug (5.0% to NNRTI, 2.7% to NRTI, 1.9% to NRTI + NNRTI, 0.3% to PI).

At 1 year, 90% of patients retained in care had viral loads less than 1,000 copies/mL. Those who discontinued ART or were lost-to-follow-up were classified as virological failure, 70% of whom met the WHO target criterion for viral load suppression at 1 year.

In patients failing ART, 67% had HIV drug-resistance to any drug, mainly NNRTI (65%) and 3TC (52%) at 1 year. Prevalence of Thymidine-associated mutations (TAM) remain limited (4.7% with more than 3 TAMs), 52% had 184V and 5% had K65R.

“Viral load suppression rates at 12 months, by both on treatment and per protocol analysis, observed in the 15 clinics surveyed in five countries are similar to those reported in cohorts in developed countries,” Bertagnolio said. “The survey results permit the identification of sites that perform above or below acceptable international standards for population based rates of viral load suppression. These surveys may be used as an alert to identify sites in need of additional support.”

Bertagnolio said a global approach to assessing HIV drug resistance is needed. “ART programs must be informed by robust programmatic evaluation of factors associated with HIV drug resistance. Routine, standardized, population-based surveillance of HIV drug resistance is imperative, and should be integrated into routine national Monitoring and Evaluation programs. Funders and national governments must step up to support and sustain population-based HIV drug resistance surveillance.” –by Ashley DeNyse

For more information:

Bertagnolio S. #52. Presented at: 18th Conference on Retroviruses and Opportunistic Infections; Feb. 27-March 2, 2011; Boston.

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WHO: HIV drug-resistance remains low