title: Adherence to first-line antiretroviral therapy affects non-virologic outcomes among patients on treatment for more than 12 months in Lusaka, Zambia.
abstract: BACKGROUND
  High-level adherence to antiretroviral therapy (ART) is associated with favourable patient outcomes. In resource-constrained settings, however, there are few validated measures. We examined the correlation between clinical outcomes and the medication possession ratio (MPR), a pharmacy-based measure of adherence.
  
  
  METHODS
  We analysed data from a large programmatic cohort across 18 primary care centres providing ART in Lusaka, Zambia. Patients were stratified into three categories based on MPR-calculated adherence over the first 12 months: optimal (> or =95%), suboptimal (80-94%) and poor (<80%).
  
  
  RESULTS
  Overall, 27 115 treatment-naïve adults initiated and continued ART for > or =12 months: 17 060 (62.9%) demonstrated optimal adherence, 7682 (28.3%) had suboptimal adherence and 2373 (8.8%) had poor adherence. When compared with those with optimal adherence, post-12-month mortality risk was similar among patients with sub-optimal adherence [adjusted hazard ratio (AHR) = 1.0; 95% CI: 0.9-1.2] but higher in patients with poor adherence (AHR = 1.7; 95% CI: 1.4-2.2). Those <80% MPR also appeared to have an attenuated CD4 response at 18 months (185 cells/microl vs 217 cells/microl; P < 0.001), 24 months (213 cells/microl vs 246 cells/microl; P < 0.001), 30 months (226 cells/microl vs 261 cells/microl; P < 0.001) and 36 months (245 cells/microl vs 275 cells/microl; P < 0.01) when compared with those above this threshold.
  
  
  CONCLUSIONS
  MPR was predictive of clinical outcomes and immunologic response in this large public sector antiretroviral treatment program. This marker may have a role in guiding programmatic monitoring and clinical care in resource-constrained settings.
authors.affiliation: Centre for Infectious Disease Research in Zambia, Lusaka, Zambia. bchi@uab.edu
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: Chi
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Cantrell
authors.forename: Isaac
authors.initials: I
authors.lastname: Zulu
authors.forename: Lloyd B
authors.initials: LB
authors.lastname: Mulenga
authors.forename: Jens W
authors.initials: JW
authors.lastname: Levy
authors.forename: Bushimbwa C
authors.initials: BC
authors.lastname: Tambatamba
authors.forename: Stewart
authors.initials: S
authors.lastname: Reid
authors.forename: Albert
authors.initials: A
authors.lastname: Mwango
authors.forename: Alwyn
authors.initials: A
authors.lastname: Mwinga
authors.forename: Marc
authors.initials: M
authors.lastname: Bulterys
authors.forename: Michael S
authors.initials: MS
authors.lastname: Saag
authors.forename: Jeffrey S A
authors.initials: JS
authors.lastname: Stringer
mesh_terms: D000293:Adolescent; D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D015496:CD4-Positive T-Lymphocytes; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology; D015497:HIV-1; D006801:Humans; D008297:Male; D054539:Medication Therapy Management / Q000706:statistics & numerical data*; D008875:Middle Aged; D013997:Time Factors; D014504:Urban Health; D055815:Young Adult; D015024:Zambia / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D019380:Anti-HIV Agents