OBJECTIVES: To assess healthcare resource utilization (HCRU)/costs for therapy switchers and non-switchers who previously had inadequate response (IR) to biologic/phosphodiesterase 4 inhibitor (PDE4i) treatment for psoriasis.

METHODS: A retrospective, observational, claims-based cohort study was conducted using the HealthCore Integrated Research Database^®. Index date was start date of biologic/PDE4i, ascertained 01-Jul-2016 to 31-Aug-2018. Adult patients (≥18 years) with psoriasis having IR to initial biologic/PDE4i 12 months after starting therapy and ≥6-months pre-index and ≥12-months post-switch continuous health plan enrollment were included. Non-switchers were assigned an imputed switch date according to switch date distribution (by month) for switchers. IR was defined as <80% biologic/PDE4i adherence; switching to non-index biologic/PDE4i; increasing index therapy dose/frequency; adding/increasing oral glucocorticoid dose/frequency; adding new conventional therapy/topical treatment/actinotherapy/retinoids/pain medication class. HCRU frequency and costs were compared during 6 months pre-index, 12 months pre-switch, and 12 months post-switch between switchers and non-switchers, without further adjustments.

RESULTS: The study included 1,122 patients with psoriasis (202 switchers and 920 non-switchers) having IR to biologic/PDE4i. Pre-index, mean systemic therapies pharmacy fill frequency was higher among switchers than non-switchers (0.7 vs. 0.3, p<0.01). Pre-switch, switchers compared with non-switchers had significantly (p<0.01) higher mean all-cause per-patient per-month outpatient visits (2.0 vs. 1.5), outpatient specialist visits (0.6 vs. 0.3), and all-cause prescription drug fills (2.1 vs. 1.9). Post-switch mean systemic therapies pharmacy fill frequency was also higher among switchers than non-switchers (7.8 vs. 4.0, p<0.01). Pre-index mean all-cause total costs were higher in switchers than non-switchers ($5840 vs. $4382, p<0.01). After switching, mean pharmacy and all-cause total costs were higher in switchers than non-switchers ($61,574 vs. $25,629 and $69,133 vs. $32,230; both p<0.01).

CONCLUSIONS: Among patients with psoriasis having IR to biologic/PDE4i, switching was associated with higher HCRU and all-cause total costs, which emphasizes importance of selecting an appropriate index therapy to maximize potential for adequate response.