OBJECTIVES:

Plaque psoriasis affects approximately 3% of Canadians, many of whom are presently untreated or undertreated. Halobetasol propionate/tazarotene (HP/TAZ) is a Health Canada-approved topical therapy for treating moderate-to-severe plaque psoriasis. The objective was to evaluate the cost-effectiveness, from a societal perspective, of HP/TAZ against other topical therapies approved and used in Québec for patients with moderate-to-severe plaque psoriasis.

METHODS:

A Markov model, informed by publicly available data, simulated four health states: “flare”, “response”, “temporary remission” and “non-response”. The model compared the standard of care (SoC) for patients with moderate-to-severe plaque psoriasis treated with topical therapies to a sequence including HP/TAZ. Estimates of relative efficacy were synthesized via a network meta-analysis. Outcomes were direct (treatment and healthcare services) and indirect costs (2022 CAD), quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio. The SoC (betamethasone/calcipotriol [BD/VDA] followed by [>] systemic therapy [ST]; [BD/VDA>ST]) was compared to HP/TAZ>ST. Alternative scenarios were (i) very high potency corticosteroid (VHPC)>BD/VDA>ST versus VHPC>HP/TAZ>ST, (ii) BD/VDA>ST versus HP/TAZ>BD/VDA>ST and (iii) BD/VDA>ST versus BD/VDA>HP/TAZ>ST. To incorporate uncertainty, parametric distributions were assigned to model parameters and 5,000 simulations were sampled. An annual discount rate of 1.5% was applied to costs and QALYs over a 5-year time-horizon (sensitivity analyses [SAs]: 1-year, 3-year and public payer perspective).

RESULTS:

In the base case, the sequence including HP/TAZ dominated SoC since incremental costs and QALYs were -$455 (95% confidence interval [CI]: -1,545 to $649) (payer perspective: -$372 [95% CI: -$1,314 to $579]) and 0.016 (95% CI: -0.016 to 0.053) per patient, respectively. Assuming a QALY is worth $50,000, the probability of being cost-effective was 0.87. Results were consistent across scenarios and SAs, except when a 1-year time horizon was employed.

CONCLUSIONS:

Considering the chronic nature of plaque psoriasis, adding HP/TAZ to SoC would lead to considerable long-term savings in Quebec while improving population health.