Long-Term Outcomes on Antiretroviral Therapy in a Large Scale-Up Program in Nigeria

Abstract

Background: While there has been a rapid global scale-up of antiretroviral therapy programs over the past decade, there are limited data on long-term outcomes from large cohorts in resource-constrained settings. Our objective in this evaluation was to measure multiple outcomes during first-line antiretroviral therapy in a large treatment program in Nigeria.

Methods: We conducted a retrospective multi-site program evaluation of adult patients (age ≥15 years) initiating antiretroviral therapy between June 2004 and February 2012 in Nigeria. The baseline characteristics of patients were described and longitudinal analyses using primary endpoints of immunologic recovery, virologic rebound, treatment failure and long-term adherence patterns were conducted.

Results: Of 70,002 patients, 65.2% were female and median age was 35 (IQR: 29-41) years; 54.7% were started on a zidovudine-containing and 40% on a tenofovir-containing first-line regimen. Median CD4+ cell counts for the cohort started at 149 cells/mm3 (IQR: 78-220) and increased over duration of ART. Of the 70,002 patients, 1.8% were reported as having died, 30.1% were lost to follow-up, and 0.1% withdrew from treatment. Overall, of those patients retained and with viral load data, 85.4% achieved viral suppression, with 69.3% achieving suppression by month 6. Of 30,792 patients evaluated for virologic failure, 24.4% met criteria for failure and of 45,130 evaluated for immunologic failure, 34.0% met criteria for immunologic failure, with immunologic criteria poorly predicting virologic failure. In adjusted analyses, older age, ART regimen, lower CD4+ cell count, higher viral load, and inadequate adherence were all predictors of virologic failure. Predictors of immunologic failure differed slightly, with age no longer predictive, but female sex as protective; additionally, higher baseline CD4+ cell count was also predictive of failure. Evaluation of long-term adherence patterns revealed that the majority of patients retained through 84 months maintained ≥95% adherence.

Conclusion: While improved access to HIV care and treatment remains a challenge in Nigeria, our study shows that a high quality of care was achieved as evidenced by strong long-term clinical, immunologic and virologic outcomes.

Fig 1. Flowchart highlighting enrolled patient population.

Fig 2. Median age at ART initiation by sex, ARV-naïve patients (N = 70,002).

Fig 3. First-line ART regimen by enrollment year, ARV-naïve patients (N = 70,002).

Fig 4. Median follow-up time on ART by first-line ART regimen, ARV-naïve patients (N = 70,002).

Fig 5. Baseline patient status by enrollment year, ARV-naïve patients.

A) median baseline CD4+cell count (cell/mm³); and, B) percentage patients by WHO clinical stage.

Fig 6. Clinical and virologic outcomes over duration on ART, ARV-naïve patients.

A) median CD4+ cell count (cells/mm³) over time on ART; and, B) percentage of patients with virologic suppression (≤400 copies/mL) over time on ART.

Fig 7. Characterization of treatment failure over time.

A) Virologic and immunologic failure rates over duration on ART, 95% CI; and, B) Percentage of patients with virologic failure within first 18 months on ART by enrollment year.

Fig 8. Long-term ART adherence for previously ARV-naïve patients on ART >6 months (N = 49,114).

A) All patients on ART; B) Median percent ART adherence by discontinuation group; and, C) Percent of patients with ≥95% adherence over time by starting ART regimen.