天候の変化は脳卒中による入院および死亡と関連する（Abstract: WP123）

脳卒中による入院率や死亡率は周囲の温度や露点温度の変化と関連する

Stroke hospitalization and death rates associated with changes in environmental temperature and dew points

脳卒中による入院率や死亡率は周囲の温度や露点温度の変化により上昇したり降下したりする可能性があるとの研究結果、2014年American Stroke Association's International Stroke Conferenceで発表された。研究者らは2009～2010年に虚血性脳卒中で入院した18歳以上の患者134,510人を同定した。その後この期間の温度や露点温度に関するデータを入手した。その結果、気温の日較差が大きく平均露点温度が高い（湿度が高いことを示唆）ことと、脳卒中入院率が高いことに関連があることを見いだした。年間平均気温が低いことは脳卒中入院および死亡と関連した。平均気温が 1°F上昇するごとに脳卒中入院確率が0.86%低下し、脳卒中による入院後に死亡する確率が1.1%低下した。1日の気温の変動および平均露点温度が上昇すると脳卒中入院確率が上昇したが、院内死亡とは関連がなかった。脳卒中リスクの高い人々は有意な気温変化や高露点温度を避けた方がよいであろうと筆者らは提案している。しかし、これらの関連のメカニズムを調査することに加え、天候の変化により脳卒中が増加する原因や天候変化の影響について理解を深める研究が今後必要であると筆者らは指摘している。

Stroke hospitalization and death rates may rise and fall with changes in environmental temperature and dew point, according to research presented at the American Stroke Association's International Stroke Conference 2014.

"Weather is not something people would typically associate with stroke risk; however, we've found weather conditions are among the multiple factors that are associated with stroke hospitalizations," said Judith H. Lichtman, Ph.D., M.P.H., study author and an associate professor in Epidemiology at the Yale School of Public Health in New Haven, Conn.

Researchers identified a nationwide sample of 134,510 people, 18 years and older, admitted to hospitals in 2009-10 for ischemic stroke. They then obtained temperature and dew point data during that period.

They found:

Larger daily temperature changes and higher average dew point (indicating higher air moisture) were associated with higher stroke hospitalization rates.
Lower average annual temperatures were associated with stroke hospitalizations and death.
With each 1°F increase in average temperature, there was a 0.86 percent decrease in the odds of stroke hospitalization and a 1.1 percent decrease in the odds of dying in the hospital after stroke.
Increases in daily temperature fluctuation and average dew point were associated with increased odds of stroke hospitalization, but not with dying in the hospital.

"This study suggests that meteorological factors such as daily fluctuations in temperature and increased humidity may be stressors that increase stroke hospitalizations," Lichtman said. "People at risk for stroke may want to avoid being exposed to significant temperature changes and high dew point and, as always, be prepared to act quickly if they or someone they know experiences stroke signs and symptoms.

"Future research is needed to better understand the cause and effect of changes in weather conditions, as well as to explore potential mechanisms for this association."

Co-authors are: Erica C. Leifheit-Limson, Ph.D., and Larry B. Goldstein, M.D.

The study was funded by the Yale School of Public Health.