Objectives:

To identify factors associated with sustained undetectable viraemia after HIV-1 seroconversion in treatment-naive patients, and to describe concomitant CD4 cell count progression.

Methods:

Seroconverters enrolled in CASCADE were assumed to control viraemia if at least two consecutive viral load measurements were< 400/500 copies/ml without treatment. Factors associated with undetectable viraemia were identified through a logistic regression. A joint model was used to describe simultaneously the CD4 cell count progression during and after that period and to identify factors associated with sustained undetectable viraemia.

Results:

Of 2176 seroconverters, 145 (6.7%) spontaneously controlled viraemia. Women were more likely than men to achieve undetectable viraemia [adjusted odds ratio (OR), 2.12; 95% confidence interval (CI), 1.49–3.12] unlike patients who reported a symptomatic primary infection (adjusted OR, 0.58; 95% CI, 0.36–0.94). AIDS and death rates were significantly lower in patients achieving undetectable viraemia than in the others. The median period of undetectable viraemia was 11.2 months; on average, CD4 cell counts remained stable during that period, and decreased with a mean rate of 5 cells/μl per month thereafter. High CD4 cell count at the beginning of undetectable viraemia and non-symptomatic primary infection favoured the preservation of undetectable viraemia.

Conclusion:

A small proportion of seroconverters appeared to be able to control HIV viraemia spontaneously, mostly those without seroconversion illness and within a few years following seroconversion; this is associated with the benefits of slower CD4 cell count decline and improved long-term prognosis. Such persons should be targeted for in depth investigation.