Objectives: To analyse the incidence, prevalence, and predictors for development of triple-class antiretroviral drug failure (TCF) in individuals infected with HIV.
Design: Population-based observational cohort study from 1 January 1995 to 31 December 2003, focusing on all 2722 recipients of highly active antiretroviral therapy (HAART) in Denmark.
Methods: We used person-years analysis, Kaplan–Meier survival curves and Cox regression analysis. TCF was defined as a minimum of 120 days with viral load > 1000 copies/ml on treatment with each of the three major drug classes.
Results: We observed 177 TCFs, yielding a crude incidence rate (IR) of 1.8 per 100 person-years [95% confidence interval (CI), 1.6–2.1]. Seven years after initiation of HAART, 17.2% (95% CI, 14.5–20.5) of antiretroviral (ART)-experienced patients, but only 7.0% (95% CI, 4.3–11.2) of ART-naive patients were estimated to have failed. After an initial rise, the IR from the third to the sixth year of HAART declined significantly for ART-experienced patients [incidence rate ratio (IRR), 0.80 per year (95% CI, 0.66–0.97); P = 0.022], and non-significantly for ART-naive patients [IRR, 0.79 per year (95% CI, 0.53–1.18); P = 0.255]. The IR for all patients being followed each year declined from 1997 to 2003 [IRR, 0.88 (95% CI, 0.81–0.96); P = 0.002]. The prevalence of TCF remained stable at less than 7% after 2000. Predictors of TCF at commencement of HAART were a CD4 cell count below 200, a previous AIDS-defining event, previous antiretroviral exposure, earlier year of HAART initiation, and young age.
Conclusions: The risk of TCF is declining in Denmark and the prevalence remains stable.
From the aOdense University Hospital, and University of Southern Denmark, Odense
bCopenhagen University Hospital Hvidovre, Hvidovre
cAarhus University Hospital Skejby, Aarhus
dAalborg Hospital, Aalborg
eHelsingør Hospital, Helsingør
fDepartment of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
gDepartment of Epidemiology, Boston University, Boston, Massachusetts, USA
hCopenhagen University Hospital Rigshospitalet, Denmark.
Received 27 September, 2004
Revised 30 January, 2005
Accepted 14 February, 2005
Correspondence to Nicolai Lohse, Department of Infectious Diseases, Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark. E-mail: email@example.com