Geospatial Quantification of Antiretroviral Therapy Consumption in Tanzania (2017-2021) Using the WHO Defined Daily Dose Methodology

ObjectivesTo quantify national and regional trends in antiretroviral therapy (ART) consumption in Tanzania from 2017 to 2021 using the World Health Organisation (WHO) Defined Daily Dose (DDD) methodology and to describe shifts in regimen composition during the transition to dolutegravir-based therapy. MethodsA retrospective descriptive analysis was conducted using programmatic dispensing data from the National AIDS and Sexually Transmitted Infections Control Programme (NASHCoP). ART dispensing records from all reporting HIV Care and Treatment Clinics were harmonised with WHO ATC/DDD codes and linked to annual population estimates. Consumption was expressed as DDDs per 1,000 inhabitants per day. Temporal trends, therapeutic class distributions, and regional variations were analysed using Power BI and R. Short-term national forecasts until 2025 were modelled using quadratic regression. ResultsBetween 2017 and 2021, ART consumption increased from 12.2 to 27.1 DDD/1,000/day (compound annual growth rate, 22.4%), with a five-year mean of 19.7 DDD/1,000/day. A total of 2,108,707 unique patients accounted for 39.7 million clinic visits in the study. The average number of visits per patient per year declined from 6.78 to 5.24, consistent with the expansion of the multi-month dispensing program (MM). Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) remained the core therapeutic class, whereas the use of integrase strand transfer inhibitors (INSTIs) has increased by more than tenfold since 2019. Dolutegravir (DTG) - based combinations (TDF/3TC/DTG) have become the predominant regimen, accounting for approximately 70% of dispensed DDDs by 2021. Regional variation narrowed over time, although the highest consumption persisted in Dar es Salaam, Mwanza, and Dodoma. Forecast modelling indicated continued moderate growth through 2025. ConclusionsThe national ART consumption in Tanzania more than doubled between 2017 and 2021, reflecting the expansion of treatment coverage, evolution of differentiated service delivery, and the transition to DTG-based regimens. The routine computation of DDD per 1,000 inhabitants per day provides a standardised and feasible metric for monitoring ART utilisation within national HIV programs.