Impact of previous virological treatment failures and adherence on the outcome of antiretroviral therapy in 2007.
BACKGROUND
Combination antiretroviral treatment (cART) has been very successful, especially among selected patients in clinical trials. The aim of this study was to describe outcomes of cART on the population level in a large national cohort.


METHODS
Characteristics of participants of the Swiss HIV Cohort Study on stable cART at two semiannual visits in 2007 were analyzed with respect to era of treatment initiation, number of previous virologically failed regimens and self reported adherence. Starting ART in the mono/dual era before HIV-1 RNA assays became available was counted as one failed regimen. Logistic regression was used to identify risk factors for virological failure between the two consecutive visits.


RESULTS
Of 4541 patients 31.2% and 68.8% had initiated therapy in the mono/dual and cART era, respectively, and been on treatment for a median of 11.7 vs. 5.7 years. At visit 1 in 2007, the mean number of previous failed regimens was 3.2 vs. 0.5 and the viral load was undetectable (<50 copies/ml) in 84.6% vs. 89.1% of the participants, respectively. Adjusted odds ratios of a detectable viral load at visit 2 for participants from the mono/dual era with a history of 2 and 3, 4, >4 previous failures compared to 1 were 0.9 (95% CI 0.4-1.7), 0.8 (0.4-1.6), 1.6 (0.8-3.2), 3.3 (1.7-6.6) respectively, and 2.3 (1.1-4.8) for >2 missed cART doses during the last month, compared to perfect adherence. From the cART era, odds ratios with a history of 1, 2 and >2 previous failures compared to none were 1.8 (95% CI 1.3-2.5), 2.8 (1.7-4.5) and 7.8 (4.5-13.5), respectively, and 2.8 (1.6-4.8) for >2 missed cART doses during the last month, compared to perfect adherence.


CONCLUSIONS
A higher number of previous virologically failed regimens, and imperfect adherence to therapy were independent predictors of imminent virological failure.
Ballif
Marie
M
Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Ledergerber
Bruno
B
Battegay
Manuel
M
Cavassini
Matthias
M
Bernasconi
Enos
E
Schmid
Patrick
P
Hirschel
Bernard
B
Furrer
Hansjakob
H
Rickenbach
Martin
M
Opravil
Milos
M
Weber
Rainer
R
D000328:Adult; D044966:Anti-Retroviral Agents / Q000494:pharmacology / Q000627:therapeutic use*; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000188:drug therapy*; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D018579:Patient Selection; D012367:RNA, Viral / Q000235:genetics; D013557:Switzerland; D017211:Treatment Failure; D019562:Viral Load / Q000187:drug effects
D044966:Anti-Retroviral Agents; D012367:RNA, Viral