A time-stratified case-crossover study on effects of heatwaves on daily outpatient visits for skin diseases in Urumqi from 2016 to 2024

Ying ZHANG; Zhe LIU; Chunyu XU; Na LI; Jingyi LIU; Haofeng YANG; Li DING; Jingxiu HAN

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A time-stratified case-crossover study on effects of heatwaves on daily outpatient visits for skin diseases in Urumqi from 2016 to 2024

VernacularTitle:2016—2024年乌鲁木齐市高温热浪与皮肤病日门诊量关系的时间分层病例交叉研究
Author: Ying ZHANG ¹ ; Zhe LIU ² ; Chunyu XU ² ; Na LI ² ; Jingyi LIU ² ; Haofeng YANG ¹ ; Li DING ¹ ; Jingxiu HAN ²
Author Information

1. Environmental Health Factors Monitoring and Evaluation Division, Urumqi Center for Disease Control and Prevention (Urumqi Institute of Health Supervision), Urumqi, Xinjiang 830002, China.
2. China CDC Key Laboratory of Environment and Population Health, National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, Beijing 100021, China.
Publication Type:Investigation
Keywords: heatwave; skin disease; outpatient volume; lag effect; time-stratified case-crossover study
From: Journal of Environmental and Occupational Medicine 2026;43(8):967-971
CountryChina
Language:Chinese
Abstract: Background Against the background of global warming, frequent heatwaves pose a major threat to public health. Objective To investigate the effects of heatwaves on outpatient visits for skin diseases in Urumqi, characterize the exposure–response relationship, identify the critical temperature threshold, and provide scientific evidence for targeted prevention and control of heat-related skin diseases. Methods Data on meteorological conditions, air quality, and dermatological outpatient visits from 10 hospitals in Urumqi were collected from January 1, 2016 to December 31, 2024. A time-stratified case-crossover design combined with a distributed lag model was adopted to construct a conditional logistic regression model, with adjustment for potential confounders, including relative humidity, air pollutants, and COVID-19 lockdown measures. With a maximum lag of 14 d, single-lag and cumulative-lag effects of heatwaves were examined, and the exposure–response relationship between temperature and the risk of dermatological outpatient visit was fitted. Results A total of 385 heatwave days were identified in Urumqi from January 1, 2016 to December 31, 2024. These days were concentrated between June and September and showed an increasing annual trend. The median daily number of dermatological outpatient visits during heatwave periods (165 cases) was significantly higher than that during control periods (114 cases) (Z=−5.108, P<0.001). After adjusting for confounders, the odds of dermatological outpatient visits during heatwaves were 1.088 times higher than those of the control period (OR=1.088, 95%CI: 1.069, 1.107). Single-lag effects were statistically significant from lag0 to lag11 (P<0.05), peaking at lag0 (OR=1.088, 95%CI: 1.069, 1.107), showing an acute and immediate effect. Cumulative-lag effects were statistically significant from 1 to 14 d (P<0.05), peaking at lag04 (OR=1.117, 95%CI: 1.099, 1.136). The exposure–response relationship indicated that the OR values increased steeply with increasing temperature when the daily mean temperature exceeded 24.2 ℃, peaking at approximately 28.1 ℃ (OR=1.400, 95%CI: 1.189, 1.649). Conclusions Heatwave exposure is significantly associated with an increased risk of dermatological outpatient visits among residents in Urumqi. The impact of high temperature on skin diseases is predominantly acute, with peak risks observed on the day of exposure and within the subsequent 4 d. A daily mean temperature of 24.2 ℃ can serve as the critical threshold for heightened dermatological consultation risk. Strengthened health education and early warning systems are recommended to mitigate heatwave-related adverse dermatological outcomes.