LAUSR

Dear Editor, Biologics and small molecule inhibitors have diversified the psoriasis therapeutic landscape with little known about their impact on phototherapy usage. In this study, we examined phototherapy utilization for psoriasis in comparison with cutaneous T-cell lymphoma (CTCL) and pruritus, and identified psoriasis treatment trends. We retrospectively obtained the annual numbers of patients diagnosed with psoriasis, CTCL, and pruritus and treated with phototherapy at Weill Cornell Medicine 2005 to 2018. For psoriasis patients, we also collected numbers of patients who received biologics, acitretin, and apremilast. Fisher's exact test was used to compare the proportion of therapy use. A negative binomial model was used to determine the incident rate ratio (IRR) of treatments. From 2005 to 2018, there were 9856, 26 193, and 663 patients diagnosed with psoriasis, pruritus, and CTCL, respectively (Table S1). There was a decrease from 13.3% to 1.3% (P < .001), and 12.3% yearly decline (IRR = 0.88, P < .001), in phototherapy use for newly diagnosed psoriasis patients. There were no significant changes in phototherapy use for CTCL and pruritus patients during this time period (Figure 1). The decrease in psoriasis phototherapy use (IRR = 0.88, P < .001) was accompanied by significant increases in biologic (IRR = 1.14, P < .001) and apremilast use (IRR = 1.39, P < .001), and decreased acitretin use (IRR = 0.92, P = .02). Biologic and apremilast utilization started to exceed phototherapy usage in 2012 and 2016, respectively (Figure 2). Among phototherapy types, the use of ultra violet B (UVB) declined significantly with an average of 13.0% yearly (IRR = 0.87, P < .001). The use of psoralen and ultraviolet A (PUVA) also trended down while excimer use has uptrended, although neither reached statistical significance (Figure 3). Although phototherapy is a well-established treatment for psoriasis, utilization decreased from 2005 to 2018. The decrease in phototherapy use was accompanied by a concomitant increase in the utilization of biologics. Cost is unlikely to be a barrier to phototherapy use, since it most cost-effective compared to biologics, with an estimated cost on average, 10 times less than biologics. Potential side effects associated with phototherapy, including erythema, burning, and increased skin cancer risk, albeit uncommon, are unlikely to deter patients from pursuing this treatment. The most likely reason for the trend toward decreased phototherapy use is the time commitment (multiple sessions per week for several months) and patient adherence required to achieve therapeutic response. Conversely, biologic dosing schedules are extremely convenient, with some requiring as few as four injections a year. Despite the trend toward increased biologic use, phototherapy is unlikely to become obsolete because it is safer to use in pregnant women and older patients with comorbidities. In addition, clinical efficacy is enhanced when phototherapy is used in conjunction with biologics. Future studies focusing on trends in combination therapy would further enrich our understanding of psoriasis treatment. Our study is limited by its retrospective design, and inclusion of a single academic center; our results may not applicable to the general population. Patients' ages and comorbidities were not considered, which may dictate the treatment strategies. In conclusion, we found that biologics and small molecule inhibitors have significantly altered the psoriasis treatment landscape. These