Lanska D J, Hoffmann R G
Veterans Affairs Medical Center, Tomah, WI 54660, USA.
Neurology. 1999 Mar 23;52(5):984-90. doi: 10.1212/wnl.52.5.984.
To identify possible contributors to the seasonal variation in stroke mortality.
Stroke and respiratory disease mortality rates were calculated from vital statistics and census data for the United States from 1938 to 1988. State-specific average temperatures by month were derived from data obtained from the National Climatic Data Center for 1938 to 1987.
Each time series was decomposed into a trend, a seasonal effect, and a residual effect. Multiple regression was used to fit both a trend and a seasonal harmonic series. Cross-correlation was used to assess the relationship between the residual time series.
There is a strong and consistent seasonal pattern of high stroke and respiratory disease mortality in the colder winter months. Stroke mortality was significantly and independently both positively associated with respiratory disease mortality and inversely associated with temperature. The sharp initial increases in both respiratory disease and stroke mortality in the late fall and early winter are synchronous, and the amplitudes are strongly associated, except for a saturation effect with extreme respiratory disease amplitudes.
Seasonal change in stroke mortality is associated with seasonal variation in both respiratory disease and temperature. Respiratory disease and temperature may influence stroke mortality nonspuriously by affecting stroke case fatality, incidence, or both.
确定可能导致卒中死亡率季节性变化的因素。
卒中及呼吸道疾病死亡率是根据1938年至1988年美国的生命统计数据和人口普查数据计算得出的。各州按月平均气温数据来自于1938年至1987年从国家气候数据中心获取的数据。
每个时间序列被分解为一个趋势、一个季节效应和一个残差效应。使用多元回归来拟合趋势和季节谐波序列。互相关用于评估残差时间序列之间的关系。
在较寒冷的冬季月份，卒中及呼吸道疾病死亡率呈现出强烈且一致的季节性模式。卒中死亡率与呼吸道疾病死亡率显著且独立地呈正相关，与气温呈负相关。深秋和初冬呼吸道疾病和卒中死亡率的急剧初始上升是同步的，且幅度密切相关，但极端呼吸道疾病幅度存在饱和效应。
卒中死亡率的季节性变化与呼吸道疾病和气温的季节性变化有关。呼吸道疾病和气温可能通过影响卒中病死率、发病率或两者，非偶然地影响卒中死亡率。
