Do temperature changes cause eczema flares? An English cohort study.

BACKGROUND: It is unclear if ambient temperature changes affect eczema. It is also unclear if people with worse disease are more susceptible to weather-related flares, or specific types of emollient offer protection. Substantiating these links may help inform action plans and patients self-management.

OBJECTIVE: To investigate the effect of short-term temperature variations on eczema symptoms in children.

METHODS: Data from a UK cohort of 519 children (6 months-12 years) with at least mild eczema, participating in a randomised trial comparing four types of emollients on eczema symptoms, were combined with observed temperature data from the Hadley Centre's Integrated Surface Database.Hot & cold weeks were defined by average regional temperature >75th or <25th percentile, January 2018-February 2020. Eczema flares were defined as ≥3 point change in patient-oriented eczema measure (POEM). Random effects logistic regression models were used to estimate the odds ratios of flares in hot & cold weeks (reference group: temperate weeks). The likelihood ratio test assessed for evidence of effect modification by disease severity and emollient type.

RESULTS: The baseline mean age was 4.9 years (SD 3.2) and POEM score was 9.2 (SD 5.5), indicating moderate eczema. 90% of participants lived within 20 km of their nearest weather station. From the 519 participants there were 6,796 consecutively paired POEMs and 1,082 flares.Seasonal variation in POEM scores was observed, suggesting symptoms worsening with colder weather in winter and improving with warmer weather in summer. Odds ratios of flares were: 1.15 (p = 0.136, 95%CI 0.96-1.39) in cold weeks, 0.85 (p = 0.045, 95%CI 0.72-1.00) in hot weeks. Likelihood ratio test showed no evidence of this differing by disease severity (p = 0.53) or emollient type used (p = 0.55).

CONCLUSIONS: Our findings are consistent with previous studies demonstrating either improvements in eczema symptoms or reduced flares in hot weather. Worse disease and different emollient types did not increase susceptibility or provide protection against temperature changes. Further work should investigate the role of sunlight, humidity, air pollution and other environmental factors.