Atopic eczema (AE) or atopic dermatitis is a chronic inflammatory skin condition that is associated with a significant burden. Phototherapy is sometimes used to treat AE when topical treatments, like corticosteroids, are insufficient or poorly tolerated.

A recent study assessed the effects of phototherapy on treating AE by exploring the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase and ClinicalTrials.gov till January 2021.

The observations were as follows:

• Thirty-two trials with 1,219 randomized participants, aged 5 to 83 years (mean: 28 years), with an equal number of males and females were included in the study.
• Participants were recruited mainly from secondary care dermatology clinics, and the study duration was, on average, 13 weeks (range: 10 days to 1year).
• The risk of bias for all key outcomes was evaluated as having some concerns or high-risk, due to missing data, inappropriate analysis or insufficient information to assess selective reporting. Assessed interventions comprised: narrowband ultraviolet B (NB-UVB; 13 trials), ultraviolet A1 (UVA1; 6 trials), broadband ultraviolet B (BB-UVB; 5 trials), ultraviolet AB (UVAB; 2 trials), psoralen plus ultraviolet A (PUVA; 2 trials), ultraviolet A (UVA; 1 trial), unspecified ultraviolet B (UVB; 1 trial), full-spectrum light (1 trial), Saalmann selective ultraviolet phototherapy (SUP) cabin (1 trial), saltwater bath plus UVB (balneophototherapy; 1 trial) and excimer laser (1 trial).
• Placebo, no treatment, another phototherapy, topical treatment or alternative doses of the same treatment were utilized as the comparators.
• Results for key comparisons were as (for scales, lower scores are better): 

NB-UVB versus placebo/no treatment-

• A larger reduction in physician-assessed signs with NB-UVB can be seen compared to placebo after 12 weeks of treatment.
• Two trials showed a small difference between NB-UVB and no treatment; another showed improved signs with NB-UVB versus no treatment.
• NB-UVB may benefit more people with itch reduction after 12 weeks of treatment than placebo.
• Another trial conveyed very little discrepancy in itch severity with NB-UVB.
• Total participants with moderate to greater global improvement may be more with NB-UVB than placebo after 12 weeks of treatment.
• NB-UVB may not influence rates of withdrawal because of the adverse events.
• One trial of NB-UVB versus placebo (18 participants, 9weeks of treatment) reported no withdrawals.
• Two trials of NB-UVB versus no treatment reported one withdrawal per group (71 participants, 8 to 12 weeks of treatment).
• It was noticed that all reported outcomes were supported with low-certainty evidence, due to the risk of bias and imprecision.
• No trials documented health-related quality of life (HRQoL). 

NB-UVB versus UVA1- 

• The evidence for NB-UVB compared to UVA1 was found to be very low certainty for all outcomes, due to the risk of bias and imprecision.
• No evidence of a difference in physician-assessed signs after 6weeks, or patient-reported itch after 6weeks was found.
• Two split-body trials which also measured these outcomes, using different scales at 7to 8weeks, reported lower scores with NB-UVB.
• One trial documented HRQoL at 6weeks.
• One split-body trial documented no withdrawals because of adverse events over 12 weeks.
• No trials documented Investigator Global Assessment (IGA). 

NB-UVB versus PUVA

• The evidence for NB-UVB compared to PUVA (8 methoxypsoralen in bath plus UVA) were judged to be very low certainty for all reported outcomes, due to the risk of bias and imprecision. 
• No evidence of a difference in physician-assessed signs after 6weeks (64.1% reduction with NB-UVB vs. 65.7% reduction with PUVA) was found. 
• No evidence of a difference in marked improvement or complete remission after 6weeks was found. 
• One split-body trial documented no withdrawals due to adverse events over 6weeks. 
• The trials did not document patient-reported symptoms or HRQoL. 

UVA1 versus PUVA 

• Very low-certainty evidence was found due to the serious risk of bias and imprecision, that PUVA (oral 5-methoxypsoralen plus UVA) reduces physician-assessed signs more than UVA1 after 3 weeks. 
• The trial did not document patient-reported symptoms, IGA, HRQoL or withdrawals due to adverse events.
• No eligible trials for the key comparisons of UVA1 or PUVA were found compared with no treatment. 

Adverse events- low rates of phototoxic reaction, severe irritation, UV burn, bacterial superinfection, disease exacerbation and eczema herpeticum were documented.

Thus on comparing with placebo or no treatment, NB-UVB may enhance physician-rated signs, patient-reported symptoms, and IGA after 12 weeks, without a difference in withdrawal due to adverse events. Evidence for UVA1 compared to NB-UVB or PUVA, and NB-UVB compared to PUVA is of very low certainty. Thus additional information is required on the safety and effectiveness of all aspects of phototherapy for treating AE.

Source: Musters AH, Mashayekhi S, Harvey J, et al. Phototherapy for atopic eczema. Cochrane Database Syst Rev. 2021;10(10):CD013870.