Cross‐Sectional Analysis of the Impact of Humidity on Acitretin Prescription Patterns Among Medicare Providers From 2013 to 2019

Acitretin is used for psoriasis and for prevention of keratinocyte carcinomas. Almost all patients experience mucocutaneous side effects, such as dry mouth and xerosis. As these side effects are amplified in low‐humidity environments, we sought to determine if humidity influenced the geographical prescription patterns of acitretin. Cross‐sectional analysis was conducted at the state level from 2013 to 2019 using Medicare Part D Claims Data and the UN’s Food and Agriculture Organization’s (FAO) Climate Information Tool AgERA5 dataset. Using all states, relative humidity percentage was a statistically significant positive predictor of acitretin prescriptions per prescriber ( β = 0.034, p = 0.038). The top 5 most humid states had higher acitretin prescriptions per prescriber (6.72 vs. 5.50, p = 0.015) compared to the bottom 5 least humid states. Moreover, the groups did not statistically significantly differ on acitretin cost ($812.36 vs. $807.29, p = 0.88), apremilast prescriptions per prescriber (9.46 vs. 8.23, p = 0.23), or apremilast cost ($2789.86 vs. $2884.37, p = 0.21). Relative humidity correlates with Medicare providers’ acitretin‐prescribing habits with prescriptions decreasing in low‐humidity environments. Recognizing the potential impact of climate on prescribing retinoids may help guide treatment for dermatologic conditions.