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TOPLINE
In a 2-year pragmatic trial of patients with moderate-to-severe atopic dermatitis (AD), add-on narrowband ultraviolet B (NB-UVB) phototherapy showed no significant effect on disease control, whereas vitamin D supplementation produced a statistically significant but clinically negligible improvement.
METHODOLOGY
- Researchers conducted a randomised, crossover, pragmatic trial spanning 2 years, in which one randomisation tested add-on NB-UVB phototherapy against observation and a separate double-blind allocation assigned patients to receive either vitamin D or placebo.
- They included 110 patients aged 15 years or older (mean age, 34.7 years) with moderate-to-severe AD who had received topical anti-inflammatory treatments (TATs) for at least 12 weeks and fewer than 100 phototherapy sessions in lifetime; 93 patients were evaluated in the primary analysis.
- Participants were administered 100,000 IU of oral vitamin D (cholecalciferol) or placebo once every 3 months over a 6-month winter treatment window; this was paired with NB-UVB sessions that started three times weekly for the first 3 weeks, followed by sessions every 2 weeks.
- The primary outcome was a hierarchical composite of repeated measures of Patient-Oriented SCORing of Atopic Dermatitis (PO-SCORAD) severity scores over 1 year and the cumulative use of TATs from October to March.
- Secondary outcomes included investigator-based severity scores (Eczema Area and Severity Index [EASI], SCORAD, and Investigator Global Assessment [IGA]) and patient-reported scores (Patient-Oriented Eczema Measure [POEM] and Dermatology Life Quality Index [DLQI]) over 2 years.
TAKEAWAY
- Vitamin D supplementation was associated with lower PO-SCORAD scores than placebo (mean difference, -5.6; P = .042), but this effect size remained below the prespecified minimum clinically important difference of 9 points.
- NB-UVB phototherapy had no significant effect on PO-SCORAD scores (mean difference, 0.83; P = .566). Neither vitamin D supplementation nor phototherapy significantly reduced the cumulative use of TATs.
- NB-UVB phototherapy significantly improved investigator-assessed EASI (mean difference, 0.07; P = .012) and SCORAD (mean difference, 3.62; P = .008) scores, whereas vitamin D supplementation had no significant effect on either measure; neither intervention significantly affected IGA scores.
- Both vitamin D supplementation (estimated effect size, 1.77; P = .011) and NB-UVB (estimated effect size, 1.08; P = .001) significantly improved patient-reported DLQI scores; vitamin D supplementation also significantly improved POEM scores (P = .035).
- Photosensitivity or erythema reactions occurred at a rate of 0.33 events per 100 patient-months (38 non-serious events in 30 patients), and no withdrawals were related to serious adverse events.
IN PRACTICE
"We were unable to demonstrate an effect of add-on phototherapy (spaced NB-UVB sessions during winter) and oral supplementation of vitamin D on patient-reported AD symptoms. It remains unclear whether this finding reflects a true absence of effect or a lack of power," the authors of the study wrote.
SOURCE
The study was led by Catherine Droitcourt, CHU Rennes, Pontchaillou Hospital, Rennes, France. It was published online on September 11, 2026, in Dermatology and Therapy.
LIMITATIONS
The trial recruited only 110 of planned 200 patients, likely leaving it underpowered to detect effects, particularly for phototherapy. Patient compliance with repeated patient-reported outcome completion was low and inconsistent.
DISCLOSURES
This study received support from the French Ministry of Social Affairs and Health (French National Program of Clinical Research). Multiple authors reported serving in advisory board roles or receiving consulting fees, speaker honoraria, or research support from pharmaceutical companies, including Sanofi-Genzyme, AbbVie, Novartis, Pfizer, and Eli Lilly. Additional author disclosures are reported in the original article.
This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
