Photoaggravated atopic dermatitis warrants more attention, testing

Photoaggravated atopic dermatitis, which affects people of varied ages and with different skin phototypes, has a significant impact on quality of life, according to a study.

“Photoaggravated atopic dermatitis (PAD) is a poorly understood subtype of AD that is worsened or provoked by exposure to UV radiation (UVR),” Kirsty J. Rutter, MRCP, of the Centre for Dermatology Research at the University of Manchester and the Northern Care Alliance NHS Foundation Trust at Salford Royal Hospital, both in Manchester, England, and colleagues wrote.

“The population prevalence of PAD has not been defined, but PAD is estimated to affect between 1.4% and 16% of people with AD,” the researchers continued.

Rutter and colleagues conducted a case series of 120 PAD patients (58% female; median age, 45 years; age range, 5 to 83 years; 87% adult patients; skin phototypes, I-VI) and analyzed clinical and photobiological data of their disease.

Study findings

Of 104 patients indicated for referrals, sunlight-provoked or photodistributed eczema was present in 62 (60%).

Of the 89 patients (74%) who could specify age at photosensitivity onset, the median age was 37 years (range, 1 to 72 years). Onset of AD occurred before age 12 years in 95 patients (79%), with onset of photosensitivity concurrent with AD onset in 16 patients (13%). Also, median age at diagnosis was an average 8 years after the median age at photosensitivity onset.

Elevated serum IgE level was found in 97 patients (81%; median, 0.168 mg/dL), while connective tissue disease was found in one patient. “Sufficient” serum vitamin D levels of 20 ng/mL or more were found in 37 subjects (31%), whereas 82 patients (69%) had vitamin D levels marked as insufficient or deficient.

Quality of life, as measured by DLQI, was “very or extremely impaired” and measured at a score greater than 10 in 80 of 103 adult patients (78%) in the past year. Similarly, a highly impaired quality of life was reported by children, with a median DLQI score of 14 for the past year.

Broadband UVR provocation using both solar-simulated radiation and broadband UV-A was tested in 116 subjects, of which 108 (93%) showed positive results.

Four patients were tested with only broadband UV-A provocation and all four had positive responses.

Subgroup analysis

The researchers performed a subgroup analysis comparing 31 patients with skin phototypes (SPT) V to VI to 89 patients with SPT I to IV.

Photosensitivity onset was earlier for patients with SPT V to VI compared with those with SPT I to IV (median age, 24 years vs. 40 years; P = .003). These patients were also younger at diagnosis (median age, 34 years vs. 52 years; P < .001) and more likely to be female (74% vs. 52%; P = .03).

While patients with SPT V to VI had lower vitamin D status and a higher frequency of abnormal monochromator phototest findings, the researchers did not find a significant different in DLQI scores between the two groups.

“This study’s findings suggest that improved knowledge of PAD presentation, demographic aspects and photoinvestigation can assist patient diagnosis and treatment and that more attention should be given to this condition,” the researchers wrote.