title: Methods to assess population effectiveness of therapies in human immunodeficiency virus incident and prevalent cohorts.
abstract: Two methods are presented for measuring population effectiveness (i.e., reduction of disease in a population in which only some receive treatment) of antiretroviral therapy among human immunodeficiency virus (HIV)-infected men at risk for acquired immunodeficiency syndrome (AIDS) and followed between January 1, 1986, and June 30, 1999, in the Multicenter AIDS Cohort Study. Method I, requiring use of a seroincident cohort, estimates relative hazards of AIDS for persons at equal duration of infection. Method II, allowing use of a seroprevalent cohort, estimates relative hazards since the beginning of therapy eras for persons starting at equal levels of prognostic markers of disease stage (CD4 cell count and HIV type 1 RNA). The follow-up interval was divided into four calendar periods to characterize different eras of antiretroviral therapy. For method I, the relative hazards were 1.52 (95% confidence interval (CI): 0.93, 2.49), 0.91 (95% CI: 0.66, 1.26), and 0.30 (95% CI: 0.18, 0.51) for the eras of no therapy, dual nucleoside therapy, and potent combination antiretroviral therapy, respectively (monotherapy was the reference era). For method II, the corresponding relative hazards were 1.52 (95% CI: 1.10, 2.09), 1.03 (95% CI: 0.77, 1.38), and 0.31 (95% CI: 0.21, 0.45). These results extend the measurement of population effectiveness from incident to prevalent cohorts and demonstrate the ability of cohort studies to complement information provided by clinical trials.
authors.affiliation: Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA. ptarwate@jhsph.edu
authors.forename: P M
authors.initials: PM
authors.lastname: Tarwater
authors.forename: J
authors.initials: J
authors.lastname: Mellors
authors.forename: M E
authors.initials: ME
authors.lastname: Gore
authors.forename: J B
authors.initials: JB
authors.lastname: Margolick
authors.forename: J
authors.initials: J
authors.lastname: Phair
authors.forename: R
authors.initials: R
authors.lastname: Detels
authors.forename: A
authors.initials: A
authors.lastname: Muñoz
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000517:prevention & control; D019380:Anti-HIV Agents / Q000627:therapeutic use; D015415:Biomarkers; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D018450:Disease Progression; D004812:Epidemiologic Methods; D006678:HIV / Q000302:isolation & purification; D015658:HIV Infections / Q000175:diagnosis / Q000188:drug therapy*; D006801:Humans; D008297:Male; D011379:Prognosis; D012367:RNA, Viral / Q000032:analysis; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D016896:Treatment Outcome
chemical_list: D019380:Anti-HIV Agents; D015415:Biomarkers; D012367:RNA, Viral