Effect of seasonality and weather on fracture risk in individuals 65 years and older.
In this large population-based study, fracture rates for hips, distal forearms, proximal humeri, and ankles were higher in winter than in other seasons, although the winter peak was small for hip fractures (p < 0.05 at all sites). Younger age between 65 and 80, living in warmer states and male gender were associated with increased winter morbidity due to fractures.


BACKGROUND
The objective was to investigate seasonal variation in the incidence of four common fractures, and explore the association of weather with risk.


METHODS
Population-based analysis of individuals age 65 and older, including fractures of the hip, the distal forearm, the proximal humerus and the ankle. Weather information was obtained from the US National Oceanic and Atmospheric Administration website.


RESULTS
For all fractures, rates were highest in winter and lowest in summer (p < 0.05 at all sites). Winter peaks were more pronounced in warm climate states, in men, and in those younger than 80 years old. In winter, total snowfall was associated with a reduced risk of hip fracture (-5% per 20 inches) but an increased risk of non-hip fractures (6-12%; p < 0.05 at all sites). In summer, hip fracture risk tended to be lower during sunny weather (- 3% per 2 weeks of sunny days; p = 0.13), while other fractures were increased (15%-20%; p < 0.05) in sunny weather.


CONCLUSIONS
Fractures contribute considerably to winter morbidity in older individuals. Younger age between 65 and 80, living in warmer states and male gender are risk factors for increased winter morbidity due to fractures. Weather affects hip fracture risk differently than the other fractures studied.
Bischoff-Ferrari
H A
HA
Department of Rheumatology and Institute of Physical Medicine, University Hospital Zurich, Gloriastrasse, 258091, Zurich, Switzerland. hbischof@hsph.harvard.edu
Orav
J E
JE
Barrett
J A
JA
Baron
J A
JA
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D009017:Morbidity; D016012:Poisson Distribution; D012307:Risk Factors; D012621:Seasons; D014887:Weather