Benefits and Costs of Biologics and Phototherapy in Psoriasis Treatment

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.

To compare the efficacy, quality-of-life gains, and cost-effectiveness of biologics, phototherapy, and step-therapy strategies.

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.

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 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.

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.

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.