title: Risk factors for short-term virologic outcomes among HIV-infected patients undergoing regimen switch of combination antiretroviral therapy.
abstract: We investigated risk factors for unfavorable virologic responses among HIV-infected patients who recently switched antiretroviral regimens. We identified HIV-infected patients who switched antiretroviral regimens (defined as adding ≥2 new medications) between 2001 and 2008 at Kaiser Permanente California. Virological response, measured after 6 months on the new regimen, was classified as (1) maximal viral suppression (HIV RNA <75/ml), (2) low-level viremia (LLV; 75-5000/ml), or (3) advanced virologic failure (>5000/ml). Potential risk factors examined included (1) HIV disease factors, e.g., prior AIDS, CD4 cell count; (2) history of antiretroviral use, e.g., therapy classes of the newly switched regimen, medication adherence, and virologic failure at previous regimens; and (3) novel patient-level factors including comorbidities and healthcare utilization. Adjusted odds ratios (aOR) for LLV and advanced virologic failure were obtained from multivariable nominal logistic regression models. A total of 3447 patients were included; 2608 (76%) achieved maximal viral suppression, 420 (12%) had LLV, and 419 (12%) developed advanced virologic failure. Factors positively associated with LLV and advanced virologic failure included number of regimens prior to switch [aOR(per regimen)=1.38 (1.17-1.62) and 1.77 (1.50-2.08), respectively], nucleotide reverse transcriptase inhibitor-only regimens (vs. protease inhibitor-based) [aOR=2.78 (1.28-6.04) and 5.10 (2.38-10.90), respectively], and virologic failure at previous regimens [aOR=3.15 (2.17-4.57) and 4.71 (2.84-7.81), respectively]. Older age, higher CD4 cell count, and medication adherence were protective for unfavorable virologic outcomes. Antiretroviral regimen-level factors and immunodeficiency were significantly associated with virologic failure after a recent therapy switch and should be considered when making treatment change decisions.
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA 91101, USA. chun.r.chao@kp.org
authors.forename: Chun
authors.initials: C
authors.lastname: Chao
authors.forename: Beth
authors.initials: B
authors.lastname: Tang
authors.forename: Leo
authors.initials: L
authors.lastname: Hurley
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Silverberg
authors.forename: William
authors.initials: W
authors.lastname: Towner
authors.forename: Melissa
authors.initials: M
authors.lastname: Preciado
authors.forename: Michael
authors.initials: M
authors.lastname: Horberg
mesh_terms: D000328:Adult; D000367:Age Factors; D044966:Anti-Retroviral Agents / Q000008:administration & dosage*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D018791:CD4 Lymphocyte Count; D002140:California; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology*; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D012307:Risk Factors; D017211:Treatment Failure; D019562:Viral Load
chemical_list: D044966:Anti-Retroviral Agents