Temperature variation and the incidence of cluster headache periods: A nationwide population study.

BACKGROUND: Cluster headache (CH) is well known to show a seasonal predilection; however, the impact of temperature and other meteorological factors on cluster periods (or bouts) has not been established.
METHODS: This nationwide survey included 758 patients with episodic CH retrieved from the Taiwan National Health Insurance Research Database from 2005 to 2009. Corresponding meteorological recordings were obtained from the Central Weather Bureau. A case-crossover study design was used to investigate the association between cluster periods and meteorological factors.
RESULTS: A total of 2452 episodes of cluster periods were recorded. The cluster periods were most frequent in the autumn and least frequent in the winter. Seasonal changes from winter to spring and from autumn to winter also increased the frequency of cluster periods. The risk of cluster periods increased when there was a higher mean temperature on event days (odds ratio (OR), 1.014, 95% confidence interval (CI), 1.005-1.023, p = 0.003) or within seven to 56 days. Either an increase or a decrease in temperature (0.05℃/day) following a warm period (mean temperature ≥26℃) was associated with the onset of cluster periods. In contrast, a greater increase in temperature (0.15℃/day) following a cold period (mean temperature < 21℃) was needed to evoke cluster periods. No such associations were found following moderate periods (21℃ ≤mean temperature <26℃). DISCUSSION: Our study shows that temperature is associated with precipitating or priming cluster periods. The influence depends on the temperature of the preceding periods. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.