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Declining risk of triple-class antiretroviral drug failure in Danish HIV-infected individuals

Lohse, Nicolaia; Obel, Nielsa; Kronborg, Gitteb; Laursen, Alexc; Pedersen, Courta; Larsen, Carsten Sd; Kvinesdal, Birgite; Sørensen, Henrik Toftf,g; Gerstoft, Janh

Epidemiology and Social

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:

© 2005 Lippincott Williams & Wilkins, Inc.