Response to HAART in non-Europeans: Conflicting data from UK centres

Doctors from two of London's leading HIV treatment centres have presented conflicting information on treatment outcomes in people infected with non-B HIV subtypes. These subtypes are predominantly carried by people who acquired HIV infection outside Europe and North America.

At the Royal Free Hospital, 50 people infected with non-B subtypes were compared with 50 matched subtype B patients from the Free's patient database. All had started HAART and had subsequent CD4 and viral load results recorded over a minimum of 24 weeks. There were no differences between the two groups in their average baseline viral load, the proportions who were treatment naïve, or in the regimens used. The groups differed only with respect to gender - women were found more frequently in the non-B group than the subtype B group.

After an average follow-up period of 75 weeks, there were no differences in the proportions whose viral load fell either below 400 or below 50 copies, or in the speed at which these two markers were reached. Similarly, there was no difference in the average fall in viral load, in the average duration of response, or in the proportions who maintained a virological response after 48 weeks of treatment.

However, a comparison between European and non-European patients at St Mary's Hospital found that non-Europeans were less likely to have undetectable viral load twelve months after starting HAART than European patients. Eighty-nine people with non-B subtypes, most of whom were Ugandan, were matched with 248 people infected with subtype B. The non-B group included a greater proportion of women than the subtype B group. After six months of HAART, viral load responses were similar across the two groups, with 81% having an undetectable viral load. However, by twelve months the groups had diverged: while 84% of the subtype B group had undetectable viral load at this point, only 56% of non-B patients were undetectable.

The St Mary's group suggest the differences they observed cannot be explained by differences in subtype response to anti-HIV drugs, given the similarity of viral load responses at the six month mark. Instead, they propose that poor adherence may explain the poorer response amongst non-B patients (though this was not measured within this study), and that there may be a need to reconsider the applicability of available adherence support measures to Africans and other non-Europeans.