Benefits and Costs of Biologics and Phototherapy in Psoriasis Treatment

Importance: Phototherapy remains an effective and cost-efficient treatment for psoriasis, yet its use is constrained by coverage policies and the inconvenience of in-office treatment. Objective: To compare the efficacy, quality-of-life gains, and cost-effectiveness of biologics, phototherapy, and step-therapy strategies. Design, Setting, and Participants: Simulation modeling study in patients with moderate to severe plaque psoriasis (Psoriasis Area and Severity Index [PASI] ≥12) using published estimates of efficacy, costs, and mappings between PASI score and quality-adjusted life-years (QALYs) from 2013 through 2025. Analysis was conducted between July 1 and November 21, 2025. Exposures: One year of treatment with a representative biologic (bimekizumab), narrowband UV-B phototherapy (home or office) or a step-therapy regimen where patients initiated phototherapy for 16 weeks and switched to biologics if PASI90 (an improvement in PASI score of ≥90%) was not achieved, continuing the more effective therapy. Main Outcomes and Measures: Main outcomes were PASI reductions at 32 weeks, QALYs monetized as $100 000 per QALY, and total treatment costs to payers. Secondary outcomes included out-of-pocket costs and net willingness to pay, defined as monetized QALYs minus costs. Sensitivity analyses considered risankizumab and adalimumab. Results: Among 500 000 simulated adult patients, the mean (SD) baseline PASI value was 20.2 (7.5). Mean (SD) PASI reductions were 91.6% (20.1%) for biologics, 71.1% (30.3%) for phototherapy, and 95.2% (10.8%) for the step-therapy regimen. Mean (SD) reductions were most variable for phototherapy (71.1% [30.3%]) and least variable for step therapy (95.2% [10.8%]). Mean (SD) QALY gains were 0.24 (0.08) for biologics, 0.18 (0.09) for phototherapy, and 0.23 (0.06) for step therapy. Mean (SD) monetized gains were $24 107 ($7916) for biologics, $17 916 ($9421) for phototherapy, and $22 560 ($6324) for step therapy. Mean (SD) annual total costs were $84 034 (0) for biologics, $14 760 (0) for office phototherapy, and $6222 (0) for home phototherapy. Mean (SD) out-of-pocket costs were $2000 (0) for biologics, $5004 ($9241) for office phototherapy, and $1450 (0) for home phototherapy. From the payer perspective, mean (SD) net willingness to pay was highest for home phototherapy ($11 694 [$9421]) and lowest for biologics (-$59 926 [$7916]). For patients, the mean (SD) willingness to pay was positive across all regimens and highest for biologics ($22 107 [$7916]), followed by home phototherapy ($16 466 [$9421]) and office phototherapy ($12 912 [$13 192]). Among biologics, payers preferred adalimumab, whereas patients preferred bimekizumab. Conclusions and Relevance: In this study, biologics provided the largest quality-of-life gains, while step-therapy strategies achieved similar benefits with less variability and lower system costs. Phototherapy remained cost-effective for payers. Divergent incentives-payers favoring phototherapy and patients favoring biologics-underscore the need to align coverage, including reduced cost sharing for home phototherapy, to improve access and system sustainability.