title: How generalizable are the results of large randomized controlled trials of antiretroviral therapy?
abstract: OBJECTIVE
  To examine the generalizability of two large randomized controlled clinical trials of antiretroviral therapy in HIV-infected individuals.
  
  
  METHODS
  The demographic, clinical and laboratory characteristics of HIV-infected participants in two antiretroviral trials (Concorde and Delta) at three study sites were compared with those of two other groups of patients to whom the trial results would be applicable: eligible patients who were screened for the trials but who did not enrol, and eligible patients who were not approached or screened for the trials.
  
  
  RESULTS
  Among enrolled participants in the Concorde and Delta trials there was an under-representation of patients who had acquired HIV infection heterosexually (P = 0.014) or through injecting drug use (P = 0.03), and a greater representation of homosexual men (P < 0.001) compared to non-enrolled participants. Trial participants in Concorde had significantly less advanced immunosuppression compared to non-trial participants (P = 0.0001), while in Delta the converse was true. Concorde participants were also much less likely to be lost to follow-up for more than a year (9%) compared to eligible but unscreened patients (40%) (P < 0.001), and screened but unenrolled patients (22%) (P = 0.035).
  
  
  CONCLUSIONS
  In applying the findings of large randomized clinical trials, it is important to establish whether there are systematic differences between the characteristics of trial participants and eligible non-participants, which might affect the generalizability of the study results. A log of the characteristics of enrolled as well as eligible but non-enrolled patients should be maintained so that the representativeness of the trial population can be evaluated.
authors.affiliation: Department of Infectious Diseases, Hammersmith Hospital, London, UK.
authors.forename: D A
authors.initials: DA
authors.lastname: Moore
authors.forename: R L
authors.initials: RL
authors.lastname: Goodall
authors.forename: N J
authors.initials: NJ
authors.lastname: Ives
authors.forename: M
authors.initials: M
authors.lastname: Hooker
authors.forename: B G
authors.initials: BG
authors.lastname: Gazzard
authors.forename: P J
authors.initials: PJ
authors.lastname: Easterbrook
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D008297:Male; D018579:Patient Selection; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D015203:Reproducibility of Results; D015983:Selection Bias
chemical_list: D019380:Anti-HIV Agents