Article Text
Abstract
Introduction To help assess morbidity associated with cold spells, a study was conducted of cold temperature and asthma hospitalisations in New York State, USA.
Methods All hospital discharges among New York State residents with a diagnosis of asthma from November 1 to April 30 were obtained for 1991 to 2006. Temperatures were collected from stations in 13 weather regions in New York State. Universal Apparent Temperature was used to take into account wind speed and humidity, and a cold spell as defined as three consecutive days with a mean Universal Apparent Temperature <the monthly 10th percentile for each region. Percent change in asthma hospitalisation during and up to 4 days after each cold spell was evaluated using time series with Generalised Additive Models adjusting for temporal trends.
Results On a statewide basis, the results indicated that asthma hospitalisations decreased during cold spells for December through March by 4.84% (95% CI −7.70 to −1.89). After cold spells, there was no change in the asthma hospitalisations for December through March, but hospitalisations increased in November (9.98%, 95% CI 5.84 to 14.27) and April (4.99%, 95% CI 1.18 and 8.94). The point estimates for the winter decrease and the November/April increase were greatest for the colder regions.
Conclusion The findings suggest that asthmatics may have difficulty acclimating to cold during the transitional months immediately before and after winter; in contrast, during a winter cold spell they may spend more time indoors, thereby preventing exacerbations.