To assess the risk of clinical progression (CP) according to the duration of time spent without complete viral load (VL) suppression compared with that associated with periods of stably suppressed viremia in HIV-infected people who started highly active antiretroviral therapy (HAART) when previously naïve to antiretrovirals.
A cohort study of patients having started HAART after enrollment in the Italian Cohort of Antiretroviral-Naive Patients (ICoNA) and being followed for at least 6 months.
Person-years spent in different categories according to the VL level and the change in VL from the most recent value before the initiation of HAART were calculated. A multivariable Poisson regression model, including potential confounders, was constructed.
A total of 3023 patients were studied. The overall rate of CP was 13.4 per 1000 person-years. Evidence for a higher risk of CP was observed for people with a current VL >10,000 copies/mL. For each year longer spent on HAART with a VL >100,000 copies/mL, a 5-fold increased risk was observed (relative risk [RR] = 5.34, 95% confidence interval [CI]: 2.83 to 1.08; P = 0.0001). An increased risk of CP in patients with current suppression <1.5 log10 copies/mL (RR = 2.34, 95% CI: 1.16 to 4.74; P = 0.02) and in those with no suppression or a VL higher than their set point (RR = 2.39, 95% CI: 1.17 to 4.89; P = 0.02) was observed compared with those with suppression of >3 log10 copies/mL, although it was not significant. Longer duration on HAART with a VL suppressed below set point seemed to confer protection against CP.
Virologic failure to antiretroviral drugs is common. The risk of CP may remain low despite a low but detectable level of HIV viremia.
From the *Istituto di Clinica delle Malattie Infettive, Università Cattolica S. Cuore of Rome, Rome, Italy; †Royal Free Centre for HIV Medicine and Department of Primary Care and Population Sciences, Royal Free and University College Medical School, Royal Free Campus, London, United Kingdom; ‡Istituto di Malattie Infettive e Tropicali, Università di Milano, Milan, Italy; §Divisione Malattie Infettive, Ospedale Civile di Verbania, Verbania, Italy; ∥Divisione Malattie Infettive, Ospedale degli Infermi di Rimini, Rimini, Italy; ¶Divisione Malattie Infettive, Ospedale di Vicenza, Vicenza, Italy; #Divisione Malattie Infettive, Ospedale Sant'Anna di Como, Como, Italy; **Divisione Malattie Infettive B, Ospedale Amedeo di Savoia di Torino, Torino, Italy; ††Divisione Malattie Infettive, Ospedale di Busto Arsizio, Arsizio, Italy; ‡‡Istituto di Malattie Infettive, Università di Bologna, Bologna, Italy; and §§Servizio Regionale di Immunologia, Ospedale Regionale Generale di Ancona, Ancona, Italy.
Received for publication January 14, 2005; accepted August 2, 2005.
The ICoNA network is supported by unrestricted educational grants from Glaxo Smith Kline, Italy.
Reprints: Rita Murri, Department of Infectious Diseases, Catholic University of Rome, L.go A. Gemelli, 8, 00168 Rome, Italy (e-mail: firstname.lastname@example.org).