title: Virological efficacy of abacavir: systematic review and meta-analysis.
abstract: OBJECTIVE
  The efficacy of abacavir/lamivudine has been reported to be inferior to tenofovir/emtricitabine. Several randomized clinical trials (RCTs) investigated the effectiveness and safety of abacavir/lamivudine and tenofovir/emtricitabine combined antiretroviral treatment (cART) and we have reviewed the available evidence.
  
  
  METHODS
  Systematic review and meta-analysis of RCTs using standard Cochrane Collaboration methodologies.
  
  
  METHODS
  We calculated risk ratios (RRs) with 95% CIs. The primary outcome was the rate of patients with viral load (VL) below the pre-defined cut-off at 48 weeks and/or at 96 weeks. Where available, results were analysed according to VL screening levels (<100,000 or >100,000 copies/mL) with conventional meta-analytical pooling by subgroups and meta-regression.
  
  
  RESULTS
  Meta-analytical pooling of RCTs with a direct comparison of abacavir/lamivudine and tenofovir/emtricitabine according to baseline VL at 48 weeks (six trials, 4118 patients) showed that the proportions of subjects with VL <50 copies/mL were similar in the overall comparison (RR 0.98; 95% CI 0.94-1.03), in the low baseline VL strata (RR 1.01; 95% CI 0.99-1.03) and in the high baseline VL strata (RR 0.96; 95% CI 0.90-1.03). Meta-regression analysis at 48 weeks confirms the results of subgroup analysis. Similar virological results were found at 96 weeks (four trials, 2003 patients). Differences in the occurrence of adverse events requiring discontinuation of treatment favoured tenofovir recipients (RR 1.26; 95% CI 0.99-1.61), but this difference, mostly related to suspected abacavir hypersensitivity reaction, was not statistically significant.
  
  
  CONCLUSIONS
  Our cumulative, cross-sectional data suggest a similar virological efficacy of abacavir/lamivudine and tenofovir/emtricitabine regardless of the baseline VL.
authors: Centre of Community Medicine & HIV Outpatient Clinic, Verona, Italy crucianimario@virgilio.it.
authors: Mario
authors: M
authors: Cruciani
authors: Department of Histology, Microbiology and Medical Biotechnology, University of Padua, Padua, Italy.
authors: Carlo
authors: C
authors: Mengoli
authors: Centre of Community Medicine & HIV Outpatient Clinic, Verona, Italy.
authors: Marina
authors: M
authors: Malena
authors: Centre of Community Medicine & HIV Outpatient Clinic, Verona, Italy.
authors: Giovanni
authors: G
authors: Serpelloni
authors: Department of Histology, Microbiology and Medical Biotechnology, University of Padua, Padua, Italy.
authors: Saverio G
authors: SG
authors: Parisi
authors: Department of HIV and Genitourinary Medicine, Chelsea and Westminster Hospital, London, UK.
authors: Graeme
authors: G
authors: Moyle
authors: Centre of Community Medicine & HIV Outpatient Clinic, Verona, Italy.
authors: Oliviero
authors: O
authors: Bosco
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000627:therapeutic use; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D015224:Dideoxynucleosides / Q000627:therapeutic use*; D000068679:Emtricitabine; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D063065:Organophosphonates / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D000068698:Tenofovir; D016896:Treatment Outcome; D000099227:Abacavir
chemical_list: D000225:Adenine; D019380:Anti-HIV Agents; D003841:Deoxycytidine; D015224:Dideoxynucleosides; D000068679:Emtricitabine; D019259:Lamivudine; D063065:Organophosphonates; D000068698:Tenofovir; D000099227:Abacavir
keywords: antiviral; meta-regression; tenofovir