Evaluation and Potential Cost-Effectiveness of Active Surveillance Pharmacovigilance for First-Line HAART in Namibia
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Background. Active surveillance pharmacovigilance (PV) is a systematic approach to medicine safety assessment and health systems strengthening. These systems can better estimate the burden of adverse events (AEs) and can generate useful information on risk factors of AEs for more effective medicine use, especially in conjunction with introduction of new medicines and/or treatment guidelines. Active surveillance has yet to be implemented on a large scale in low- and-middle income countries. This project aimed to evaluate an active surveillance pilot program for first-line antiretroviral therapy (ART) at sentinel sites in Namibia, project findings to the national level to evaluate potential cost-effectiveness, and demonstrate use of active surveillance data. Methods. Sentinel sites were outpatient ART clinics at the Windhoek Central Hospital and Katutura Intermediate Hospital. An active surveillance data collection form was developed and placed into patient charts. Adults naïve to ART were enrolled from August 2012-April 2013. Physicians recorded ART and health information during each follow-up visit, including presence or absence of AEs. Following evaluation of this data, a cost-utility analysis from a governmental perspective compared active surveillance PV to spontaneous reporting PV for highly active antiretroviral therapy (HAART) in Namibia. Programmatic data from a sentinel site active surveillance program in Namibia conducted from August 2012-April 2013 was projected to all HIV-infected adults initiating HAART in Namibia. Costs (PV program, HAART, adverse event [AE] treatment), quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs, 2015 U.S. dollars/QALY) were evaluated. Analysis was completed for (1) a cohort analysis in which a single cohort beginning HAART in 1-year in Namibia were followed over their remaining lifetime and (2) a population analysis in which patients continued to enter and leave care and treatment over 10 years. Finally, we examined a potential use of active surveillance data by examining incidence of an AE. Data from the active surveillance forms was used to evaluate the incidence nephrotoxicity in those exposed to the HAART drug tenofovir . Results. A total of 413 patients were included from August 2012 to April 2013. Average age was 37 years; 51% of patients were at WHO Clinical Stage 1; and mean baseline CD4 count was 216. The most common ART regimen was tenofovir/lamivudine/nevirapine. Presence or absence of AEs was recorded in active surveillance forms for 94\% of first follow-up visits. In total, 66 patients experienced 119 AEs of any severity. Incidence of experiencing at least one AE was 33 per 100 person-years. Most common AEs were rash and abdominal pain. On active surveillance forms, demographic variables were missing in 14% of patients and follow-up visits were recorded for 82% of patients. For the cost-effectiveness cohort analysis totals were $28,675,900 and 184,076 QALYs for care and treatment under active surveillance PV versus $23,922,400 and 182,292 QALYs for care and treatment under spontaneous reporting PV, resulting in an ICER of $3,949 for active surveillance compared to spontaneous reporting PV. In the population analysis active surveillance was cost saving. Results were sensitive to quality-of-life associated with AEs. In this study population, incidence of nephrotoxicity was 15 per 100 person-years. However, after adjustment for demographics and comorbidities, nephrotoxicity was not statistically significantly associated with tenofovir exposure. Conclusions. Completeness of AE recording on active surveillance forms was high. With improved logistical considerations, such as incorporation of active surveillance forms into medical records, long-term active surveillance programs could be successful. Active surveillance pharmacovigilance was projected to be a highly cost-effective system to improve treatment for HIV in Namibia. Active surveillance PV may be valuable to improve the lives of HIV patients and more efficiently allocate health resources in Namibia. Tenofovir was found to be a generally safe medicine, though results were limited by a small sample size.
- Pharmaceutics