Weather cold? Watch out for stroke

http://www.ncbi.nlm.nih.gov/pubmed/21273573

Stroke. 2011 Jan 27. [Epub ahead of print]
Innovative Approaches Helpful to Enhance Knowledge on Weather-Related Stroke Events Over a Wide Geographical Area and a Large Population.
Morabito M, Crisci A, Vallorani R, Modesti PA, Gensini GF, Orlandini S.

From the Interdepartmental Centre of Bioclimatology, University of Florence, Firenze, Italy; the Institute of Biometeorology, National Research Council, Firenze, Italy; Clinica Medica and Cardiologia, University of Florence, Firenze, Italy; and Don Carlo Gnocchi Foundation, Centro S. Maria agli Ulivi, Onlus IRCCS, Pozzolatico, Italy.
Abstract
BACKGROUND AND PURPOSE: Results on the effect of weather on stroke occurrences are still confusing and controversial. The aim of this study was to retrospectively investigate in Tuscany (central Italy) the weather-related stroke events through the use of an innovative source of weather data (Reanalysis) together with an original statistical approach to quantify the prompt/delayed health effects of both cold and heat exposures.

METHODS: Daily stroke hospitalizations and meteorologic data from the Reanalysis 2 Achieve were obtained for the period 1997 to 2007. Generalized linear and additive models and an innovative modeling approach, the constrained segmented distributed lag model, were applied.

RESULTS: Both daily averages and day-to-day changes of air temperature and geopotential height (a measure that approximates the mean surface pressure) were selected as independent predictors of all stroke occurrences. In particular, a 5°C temperature decrease was associated with 16.5% increase of primary intracerebral hemorrhage of people ≥65 years of age. A general short-term cold effect on hospitalizations limited to 1 week after exposure was observed and, for the first time, a clear harvesting effect (deficit of hospitalization) for cold-related primary intracerebral hemorrhage was described. Day-to-day changes of meteorologic parameters disclosed characteristic U- and J-shaped relationships with stroke occurrences.

CONCLUSIONS: Thanks to the intrinsic characteristic of Reanalysis, these results might simply be implemented in an operative forecast system regarding weather-related stroke events with the aim to develop preventive health plans.