Annual Costs Incurred in Managing Adverse Drug Reactions Attributable to Fixed-Dose Combination Highly Active Antiretroviral Therapy in an Outpatient Antiretroviral Clinic in Gauteng: A Budget Impact Analysis.

OBJECTIVES

This study aimed to identify adverse drug reactions (ADRs) attributable to tenofovir (TDF)- and zidovudine (AZT)-based fixed-dose combinations of highly active antiretroviral (ARV) therapy and subsequently determine the annual costs incurred in managing these ADRs and the budget implications in an outpatient ARV clinic in Mamelodi, Pretoria.

METHODS

This retrospective cohort study reviewed deidentified clinical data for ADRs. Medical charts of human immunodeficiency virus-positive patients, who were receiving either TDF- or AZT-based fixed-dose combinations of ARV therapy, were analyzed. Costs were converted to US dollars using the rate of US$1 equivalent to ZAR14.3853. Based on the costs and the incidence rates of ADRs observed in the analysis, a decision tree model was established to estimate the cost impact of ADR management on the clinic's budget.

RESULTS

A total of 469 patient files were analyzed (62% female vs 38% male). The mean age at the start of ARV therapy for the cohort was 36.6 years (95% confidence interval 35.74-37.45), and the mean baseline CD4 count was 380 (95% confidence interval 343-418). The incidence of ADRs to TDF- or AZT-based fixed-dose combinations of ARV therapy was found to be 24.95%. The study revealed that US$29.70 was the cost attributed to ADRs owing to TDF-based regimens, whereas US$32.53 was the cost attributed to ADRs owing to AZT-based regimens, per patient, annually. Costs attributed to gastrointestinal-related ADRs were the highest in comparison with other ADRs. The estimated total cost of ADRs attributed to AZT-based therapy was US$556.40, and the estimated total cost of ADRs attributed to TDF-based ARV therapy per annum was US$2348.80 for the 1221 patients who started receiving ARV therapy between July 2017 and June 2018 at the clinic.

CONCLUSIONS

Despite the estimated costs related to ADRs in the study being lower than those in similar studies, there remains a notable budget impact, particularly in a resource-limited setting. The study findings allow for improved budget forecasts in an ARV clinic setting.