Influence of climate on pediatric alopecia areata flares

We recently found that the frequency of alopecia areata (AA) flares follows seasonal patterns, with the highest number of flares during fall and the lowest number during summer, and explored the relationship between climate aspects and AA flares. Information on date of disease onset, first flare and second flare was extracted from the medical records of 336 pediatric AA patients (ages 1 to 12), totaling 520 episodes of AA in Philadelphia, Pennsylvania. Frequency of flares in each month was calculated. Monthly values of meteorological variables including mean ambient temperature, UV index, air pressure, humidity, cloudiness, wind speed, wind gust, number of days with rain, volume of precipitation, number of days with sun, and hours of sunlight in Philadelphia were obtained from World Weather Online. Using Spearman rank correlation (rs) analysis, there were significant correlations (p<0.05) between flare frequency and mean air pressure (rs = 0.76), number of days with sun (rs = 0.71), mean UV index (rs = -0.70) and hours of sunlight per month (rs = -0.61). Stratified analyses based on atopic comorbidities revealed that the correlations between AA flare frequency and the 4 meteorological variables was stronger and significant only in atopic patients compared to patients without atopy. In atopic patients, significant correlations also appeared between flare frequency and temperature (rs = -0.72), precipitation (rs = -0.71) and number of days with rain (rs = -0.68). Our results suggest that relationships exist between climate and AA flare frequency. Furthermore, atopic AA patients are more susceptible to the impact of climate. Physicians may counsel AA patients on these relationships. Future studies should explore how these aspects of climate affect AA pathogenesis at the molecular level.