Use of generic ritonavir-boosted darunavir and dolutegravir for second line antiretroviral therapy is cost-effective in Zambia: a 10-year modelling analysis

Title

Use of generic ritonavir-boosted darunavir and dolutegravir for second line antiretroviral therapy is cost-effective in Zambia: a 10-year modelling analysis

Presenter

Jennifer Campbell

Authors

J. Campbell * (1), J. Estill (2), Z. Panos (3), J. Harwell (4), C. Chimhundu (5), H. Shakwelele (6), P. Haimbe (6), C. Amole (3), S. Sivile (7), L. Mulenga (7)

Institutions

(1) Clinton Health Access Initiative, Analytics and Implementation Research, Boston, United States, (2) Estill Epidemiology Consulting, Tallin, Estonia, (3) Clinton Health Access Initiative, HIV Access Program, Boston, United States, (4) Clinton Health Access Initiative, Clinical Sciences Team, Boston, United States, (5) Clinton Health Access Initiative, HIV Access Program, Harare, Zimbabwe, (6) Clinton Health Access Initiative, HIV Program, Lusaka, Zambia, (7) Ministry of Health, Lusaka, Zambia

BACKGROUND: Zambia has over one-million adults on antiretroviral therapy (ART), with almost 50 thousand accessing second-line (2L) treatment. The national HIV program recently added newly accessible generic ritonavir-boosted darunavir (DRV/r) as a best-in-class protease inhibitor (PI) alternative option to replace lopinavir-ritonavir (LPV/r) and/or atazanavir-ritonavir (ATV/r) for eligible 2L patients. This, together with use of dolutegravir (DTG) in 2L, offers opportunities to optimize 2L regimens.
METHODS: We used Zambia program data as of January 2021 (with 80% of 2L patients on LPV/r and 20% on ATV/r), to populate a Markov state-transition model, coded in R. Four likely policy scenarios (Standard of Care (SOC) and three comparators) were defined to compare the cost-effectiveness of 2L ART optimization strategies: 1) SOC: uses LPV/r and ATV/r at their current breakdown in 2L; 2) C1: replaces LPV/r with DRV/r; 3) C2: replaces both LPV/r and ATV/r with DRV/r; and 4) C3: uses DTG for all non-nucleosidereverse transcriptase inhibitor failures, and DRV/r for DTG failures. The ART patient cohort transitions through health states including: ART status, viral load suppression status, CD4 cell count, opportunistic infections (OI). Published utility weights were applied to health states to estimate quality-adjusted-life-years (QALYs). Costs included all aspects of treatment from the health systems perspective and used public reference prices for annual treatment costs (DRV/r-$213, LPV/r-$227, ATV/r-$164, DTG-$32). Failure and retention on different regimens were parameterized using published literature, standardized to account for multiple studies. The WHO-CHOICE definition was used to determine cost-effectiveness (US$1050 per capita GDP in Zambia), 3% discounting was applied. Results exclude patients that did not migrate to 2L.
RESULTS: Comparator scenarios C1 and C3 were cost-saving compared to the SOC, QALYs increased by 3% and 5%, respectively, while 10-year costs decreased by 2% and 5%, respectively. Comparator C2 showed increased QALYs (4.5%) with 4% increased costs; the incremental cost-effectiveness ratio (ICER) is considered highly cost-effective at US$411/QALY gained.
CONCLUSIONS: DRV/r will improve health outcomes and is cost-effective when replacing LPV/r and ATV/r. Using DTG in 2L offers additional cost savings, and combined with DRV/r presents an optimal approach for 2L optimization, allowing programs to use the best-in-class drug.

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