Assessing the efficacy of narrowband UVB phototherapy using digital patient questionnaires and patient-reported outcome measures (PROMs): An observational cohort study of patients with psoriasis and eczema

Abstract

Phototherapy is a cost-effective and safe treatment for various inflammatory skin disorders. To enhance the efficiency of phototherapy delivery and understand its effects on patient outcomes, we designed digital phototherapy-specific patient questionnaires. These were administered via text message before initiation and after completion of phototherapy. We present a single-centre observational cohort study of psoriasis and eczema patients treated with Narrowband UVB (NB-UVB) phototherapy between March 2021 and December 2023.

Data was collected as part of a service improvement project and is consequently exempt from ethical approval requirements. NB-UVB phototherapy (311–312 nm) was administered using Waldmann UV7002 and UB5002 cabinets equipped with Philips NB-UVB TL F79-120W/01 and F72-100W/01 bulbs, respectively. The treatment frequency was 2–3 times per week at an initial dose of 70% of the minimal erythema dose, with 20% increments. Phototherapy was stopped once the skin was clear or almost clear, except for eczema, where the treatment frequency and dose were reduced until discontinuation.¹

Patient questionnaires incorporated demographic and clinical information, and patient-reported outcome measures (PROMs). PROMs collected included the Dermatology Life Quality Index (DLQI), assessing dermatology-related quality of life (QoL); the 5-point Patient Global Assessment (PtGA), measuring patient-perceived disease activity (“0 = clear” to “4 = severe”); and the 11-point Itch Numeric Rating Scale (INRS), examining itchiness severity over the previous 24 h (“0 = no itch” to “10 = worst imaginable itch”).^2-4 Eczema patients also completed the Patient Oriented Eczema Measure (POEM), evaluating eczema disease severity.⁵

In total, 379 patients (psoriasis: n = 221, eczema: n = 158) treated with NB-UVB phototherapy completed the pretreatment questionnaire. The final study sample comprised 97 patients (psoriasis: n = 72/221 [32.6%]; eczema: n = 25/158 [15.8%]) who completed both pre- and posttreatment questionnaires. Wilcoxon signed-rank test with calculation of the Vargha–Delaney A effect size was performed to compare the pre- and posttreatment PROMs scores. p < 0.05 was considered statistically significant. All statistical analyses were performed using R software version 4.3.2.

The demographic and clinical characteristics of the study cohort are presented in Table 1.

Table 2 shows the pre- and post-phototherapy PROMs scores in psoriasis and eczema patients. In psoriasis, NB-UVB significantly improved QoL measured by DLQI, reducing disease impact from moderate before treatment to no effect afterward (p < 0.001). 80.6% (n = 58/72) of patients achieved the minimal clinically important difference (MCID) of 4 points in DLQI improvement.⁶ NB-UVB reduced disease severity based on PtGA (p < 0.001), with 75% (n = 54/72) showing improvement of ≥2 points. Pruritus decreased significantly from moderate to mild after treatment (p < 0.001). 52.8% (n = 38/72) of patients reached the MCID of 4 points improvement in INRS.⁶

In eczema, NB-UVB significantly improved QoL measured by DLQI, decreasing disease impact from moderate to a small effect after treatment (p < 0.001). 64% (n = 16/25) of patients reached the MCID of 4 points in DLQI improvement. Disease severity, measured by PtGA and POEM, decreased significantly from moderate to mild (PtGA) and mild-to-moderate (POEM) after treatment (p < 0.001). One-third of patients (36%, n = 9/25) had a PtGA improvement of ≥2 points and 72% (n = 18/25) of patients experienced improvements reaching the MCID of 4 points in POEM.⁶ Pruritus decreased significantly from moderate to mild-to-moderate after treatment (p = 0.007). 52% (n = 13/25) and 40% (n = 10/25) of patients reached the MCID of 2 and 4 points respectively on INRS.⁶

Overall, our study reaffirms the effectiveness of NB-UVB phototherapy in a multi-ethnic patient cohort with moderate-to-severe psoriasis and eczema under real-world conditions, showing high improvement rates comparable to other systemic treatments.^{7, 8} Notably, the improvement in PROMs was higher in psoriasis compared to eczema. We acknowledge the low completion rate of post-phototherapy questionnaires, highlighting the need to improve the response collection system after discharge from phototherapy. Lastly, PROMs emerge as a valuable tool in phototherapy, enhancing its efficacy assessment in daily clinical practice.

Study conception and design: Evangelos Christou and John Ferguson. Data collection: Evangelos Christou and John Ferguson. Analysis and interpretation of results: Evangelos Christou and Myrto Kastrisiou, and John Ferguson. Draft manuscript preparation: Evangelos Christou, Myrto Kastrisiou, and John Ferguson. All authors reviewed the results and approved the final version of the manuscript.

Evangelos Christou and Myrto Kastrisiou have no conflicts of interest to declare. John Ferguson is a paid advisor to INCYTE. He has contributed to funded research for Pfizer on vitiligo and skin cancer risk, is the CI in the UK for Pfizer's upcoming trial examining the benefits of Ritlecitinib for vitiligo patients and is also responsible for the LA Roche Posay Photobiology Scholarship for the BPG. He is the CI for an NIHR-registered registry, the Vitiligo Registry and Bioresource (VOICE) funded by the British Skin Foundation.

The research was conducted in accordance with the principles embodied in the Declaration of Helsinki and in accordance with local statutory requirements.