Annual costs incurred on managing adverse drug reactions attributable to fixed-dose combination Highly Active Anti-Retroviral Therapy (HAART) in an outpatient ARV clinic in Gauteng.

Abstract

Objective The aim of the study is to identify adverse drug reactions attributable to tenofovir- and zidovudine-based fixed-dose combinations of highly active anti-retroviral therapy and, subsequently, to determine the annual costs incurred managing these adverse drug reactions and the budget implications of these costs at an outpatient anti-retroviral clinic in Mamelodi, Pretoria. Methods This retrospective cohort study reviewed de-identified clinical data for adverse drug reactions. The study was carried out at Stanza Bopape ARV Clinic in Mamelodi, Pretoria. De-identified medical charts of HIV-positive patients were analysed for clinical information and laboratory data of adult patients who started on HAART between July 2017 and June 2018. Data collection commenced in October 2018. Based on the costs and the incidence rates of adverse drug reactions observed in the analysis, a decision tree model was established to estimate the cost impact of adverse drug reaction management on the clinic¶s budget. Results A total of 469 patient files were analysed (62% female vs 38% male). The mean age at the start of anti-retroviral therapy for the cohort was 36.6yrs (95% CI 35.74-37.45) and the mean baseline CD4 count was 380 (95% CI 343-418). Incidence of adverse drug reactions to tenofovir- or zidovudine-based fixed-dose combinations of anti-retroviral therapy was found to be 24.95%. The ADRs reported with the use of TDF and AZT based HAART regimens were rash (n=45, 27%), decreased glomerular filtration rate (n=34, 21%), trouble sleeping (n=39, 21%), severe diarrhoea (n=19, 12%), nausea and vomitting (n=18, 11%), decreased heamoglobin or anaemia (n=4, 2%), headaches (n=4, 2%), dizziness (n=2, 5.3%). The study revealed that ZAR427.30 was the cost attributed to adverse drug reactions due to tenofovir-based regimens whilst ZAR467.94 was the cost attributed to adverse drug reactions due to zidovudine-based regimens, per patient, annually. Costs attributed to gastro-intestinal related adverse drug reactions were the highest in comparison to other adverse drug reactions. Estimated total cost of adverse drug reactions attributed to zidovudine-based therapy was ZAR8003.98 (US$556.40) and estimated total cost of adverse drug reactions attributed to tenofovir-based anti-retroviral therapy per annum was ZAR33 788, 23 (US$2348.80) for 1221patients initiated on antiretroviral therapy between July 2017 and June 2018. Conclusion Despite our estimated costs to the clinic, due to adverse drug reactions, being lower than similar studies, there remains a notable budget impact on a resource-limited setting.These estimates will allow for cost due to adverse drug reactions caused by tenofovir- and zidovudine-based anti-retroviral therapy to be accounted for in budgets at the antiretroviral clinic.