Adherence to first-line antiretroviral therapy affects non-virologic outcomes among patients on treatment for more than 12 months in Lusaka, Zambia.
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.
Chi
Benjamin H
BH
Centre for Infectious Disease Research in Zambia, Lusaka, Zambia. bchi@uab.edu
Cantrell
Ronald A
RA
Zulu
Isaac
I
Mulenga
Lloyd B
LB
Levy
Jens W
JW
Tambatamba
Bushimbwa C
BC
Reid
Stewart
S
Mwango
Albert
A
Mwinga
Alwyn
A
Bulterys
Marc
M
Saag
Michael S
MS
Stringer
Jeffrey S A
JS
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
D019380:Anti-HIV Agents