RT Journal A1 Elzi L, Marzolini C, Furrer H, et al T1 TReatment modification in human immunodeficiency virus–infected individuals starting combination antiretroviral therapy between 2005 and 2008 JF Archives of Internal Medicine JO Archives of Internal Medicine YR 2010 FD January 11 VO 170 IS 1 SP 57 OP 65 DO 10.1001/archinternmed.2009.432 UL http://dx.doi.org/10.1001/archinternmed.2009.432 AB Background  Adverse effects of combination antiretroviral therapy (CART) commonly result in treatment modification and poor adherence.Methods  We investigated predictors of toxicity-related treatment modification during the first year of CART in 1318 antiretroviral-naive human immunodeficiency virus (HIV)–infected individuals from the Swiss HIV Cohort Study who began treatment between January 1, 2005, and June 30, 2008.Results  The total rate of treatment modification was 41.5 (95% confidence interval [CI], 37.6-45.8) per 100 person-years. Of these, switches or discontinuations because of drug toxicity occurred at a rate of 22.4 (95% CI, 19.5-25.6) per 100 person-years. The most frequent toxic effects were gastrointestinal tract intolerance (28.9%), hypersensitivity (18.3%), central nervous system adverse events (17.3%), and hepatic events (11.5%). In the multivariate analysis, combined zidovudine and lamivudine (hazard ratio [HR], 2.71 [95% CI, 1.95-3.83]; P < .001), nevirapine (1.95 [1.01-3.81]; P = .050), comedication for an opportunistic infection (2.24 [1.19-4.21]; P = .01), advanced age (1.21 [1.03-1.40] per 10-year increase; P = .02), female sex (1.68 [1.14-2.48]; P = .009), nonwhite ethnicity (1.71 [1.18-2.47]; P = .005), higher baseline CD4 cell count (1.19 [1.10-1.28] per 100/μL increase; P < .001), and HIV-RNA of more than 5.0 log10 copies/mL (1.47 [1.10-1.97]; P = .009) were associated with higher rates of treatment modification. Almost 90% of individuals with treatment-limiting toxic effects were switched to a new regimen, and 85% achieved virologic suppression to less than 50 copies/mL at 12 months compared with 87% of those continuing CART (P = .56).Conclusions  Drug toxicity remains a frequent reason for treatment modification; however, it does not affect treatment success. Close monitoring and management of adverse effects and drug-drug interactions are crucial for the durability of CART.