Weather changes associated with hospitalizations for cardiovascular diseases and stroke in California, 1983-1998.

Poisson regression models were used to evaluate associations between temperature, precipitation, days of extreme heat, and other weather changes (lagged 7 days), as well as El Niño events, with hospitalizations for acute myocardial infarction, angina pectoris, congestive heart failure, and stroke in three California regions. Temperature changes were defined as a 3 degrees C decrease in maximum temperature or a 3 degrees C increase in minimum temperature. Temperature and precipitation were analyzed separately for normal weather periods and El Niño events, and for both weather periods combined. Associations varied by region, age, and gender. In Los Angeles, temperature changes resulted in small changes in hospitalizations. Among San Francisco residents 70+ years of age, temperature changes increased hospitalizations for nearly all outcomes from 6% to 13%. Associations among Sacramento residents were similar to those in San Francisco: among men 70+ years of age, temperature changes increased hospitalizations by 6%-11% for acute myocardial infarction and congestive heart failure, and 10%-18% for stroke. El Niño events were consistently and significantly associated with hospitalizations only in San Francisco and Sacramento, and then only for angina pectoris (increasing hospitalizations during El Niño events). These exploratory analyses merit further confirmation to improve our understanding of how admissions to hospitals for cardiovascular disease and stroke change with changing weather. Such an understanding is useful for developing current public health responses, for evaluating population vulnerability, and for designing future adaptation measures.

Association of normal weather periods and El Niño events with hospitalization for viral pneumonia in females: California, 1983-1998.

OBJECTIVES: This study examined associations between weather and hospitalizations of females for viral pneumonia during normal weather periods and El Niño events in the California counties of Sacramento and Yolo, San Francisco and San Mateo, and Los Angeles and Orange. METHODS: Associations between weather and hospitalizations (lagged 7 days) for January 1983 through June 1998 were evaluated with Poisson regression models. Generalized estimating equations were used to adjust for autocorrelation and overdispersion. Data were summed over 4 days. RESULTS: Associations varied by region. Hospitalizations in San Francisco and Los Angeles increased significantly (30%-50%) with a 5 degrees F decrease in minimum temperature. Hospitalizations in Sacramento increased significantly (25%-40%) with a 5 degrees F decrease in maximum temperature difference. The associations were independent of season. El Niño events were associated with hospitalizations only in Sacramento, with significant decreases for girls and increases for women. CONCLUSIONS: The results suggest that viral pneumonia could continue to be a major public health issue, with a significant association between weather and hospitalizations, even as the global mean temperature continues to rise. An understanding of population sensitivity under different weather conditions could lead to an improved understanding of virus transmission.