287 - Association between heat stress and pediatric migraine: a nationwide time-stratified case-crossover study in Japan

Publication Number: 2277.287

Kazuma Shinno, National Center for Child Health and Development, Setagaya-ku, Tokyo, Japan; Yusuke Okubo, National Center for Child Health and Development, Setagaya, Tokyo, Japan

Background: Migraine is a common and disabling neurological disorder in children, and environmental factors like low pressure can trigger attacks. Studies in adults have suggested that weather and air pollution may induce migraine attacks, and temperature-related stress has also been proposed as a potential trigger. However, evidence remains scarce regarding the effect of heat stress on migraine risk in pediatric populations.

Objective: We aimed to investigate the short-term association between heat stress, measured by wet bulb globe temperature (WBGT), a comprehensive heat stress index, and the risk of migraine onset among Japanese children.

Design/Methods: We performed a time-stratified case-crossover study using a nationwide administrative claims database linked with meteorological and WBGT data from 47 prefectures in Japan between 2010 and 2024. The study population included children aged 6-18 years newly diagnosed with migraine. Heat stress during the warm season was defined using the daily maximum WBGT, categorized as high (≥28 °C) or low ( < 28 °C). Each patient served as their own control, with referent days matched by day of week, month, and year. Conditional logistic regression models incorporating a distributed lag non-linear model (DLNM) were applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for migraine onset across WBGT levels, adjusting for meteorological confounders.

Results: A total of 7,368 children aged 6-18 (42.5% male) were diagnosed with migraine, with a median age at study entry of 10.6 years (interquartile range: 7.7-13.2 years). Higher WBGT levels (≥28 °C) were associated with a decreased risk of migraine onset in the multivariable analysis (OR: 0.91; 95% CI: 0.83-1.00; P < 0.05). No significant association was observed in the univariable analysis (OR: 0.92; 95% CI: 0.85-1.00; P = 0.06), nor when WBGT was analyzed as a continuous variable in either univariable (OR: 1.00; 95% CI: 0.99-1.01; P = 0.83) or multivariable models (OR: 1.00; 95% CI: 0.99-1.01; P = 0.91). The DLNM, modeled for lag 0-3 days, showed a consistent inverse pattern, with cumulative odds ratios below unity across WBGT levels and the strongest inverse effect at lag 0-1 day.

Conclusion(s): Higher WBGT levels were associated with a reduced short-term risk of pediatric migraine, suggesting a potential adaptive response to heat stress and highlighting the need for further research on behavioral and physiological mechanisms.

Table 1. Demographics of the study participants (n = 7,368, male: 42.5%)
IQR: interquartile range

Table 2. The association between heat stress and the risk of migraine onset among Japanese children
In the multivariable analysis, the effects of heat stress on the risk of migraine were adjusted for precipitation, average pressure, and average wind speed. WBGT is derived from air temperature, humidity, and radiant heat; thus, they were not included as covariates in the analyses.
WBGT: wet bulb globe temperature; 95% CI: 95% confidence interval

Figure 1. Cumulative and lag-specific effects of WBGT on migraine onset (multivariable-adjusted, distributed lag non-linear model)
(A) Cumulative exposure-response relationship showing a consistent inverse association, with the cumulative odds ratio (solid line) and 95% confidence interval (shaded area) remaining below unity at higher WBGT levels.
(B) Lag-response curve for a WBGT of 28.3 °C, demonstrating the strongest inverse effect at lag 0-1 days and attenuation toward null by lag 3 days. WBGT: wet bulb globe temperature