Although the association of high temperatures with mortality is well-documented, the association with morbidity has seldom been examined. We assessed the potential impact of hot weather on hospital admissions due to cardiovascular and respiratory diseases in New York City. We also explored whether the weather-disease relationship varies with socio-demographic variables. We investigated effects of temperature and humidity on health by linking the daily cardiovascular and respiratory hospitalization counts with meteorologic conditions during summer, 1991–2004. We used daily mean temperature, mean apparent temperature, and 3-day moving average of apparent temperature as the exposure indicators. Threshold effects for health risks of meteorologic conditions were assessed by log-linear threshold models, after controlling for ozone, day of week, holidays, and long-term trend. Stratified analyses were used to evaluate temperature-demographic interactions. For all 3 exposure indicators, each degree C above the threshold of the temperature-health effect curve (29°C–36°C) was associated with a 2.7%–3.1% increase in same-day hospitalizations due to respiratory diseases, and an increase of 1.4%–3.6% in lagged hospitalizations due to cardiovascular diseases. These increases for respiratory admissions were greater for Hispanic persons (6.1%/°C) and the elderly (4.7%/°C). At high temperatures, admission rates increased for chronic airway obstruction, asthma, ischemic heart disease, and cardiac dysrhythmias, but decreased for hypertension and heart failure. Extreme high temperature appears to increase hospital admissions for cardiovascular and respiratory disorders in New York City. Elderly and Hispanic residents may be particularly vulnerable to the temperature effects on respiratory illnesses.

A peer-reviewed open access journal published by the National Institute of Environmental Health Sciences

This study assessed the association between high temperatures and increased odds of hospitalization for renal diseases that, to date, has been examined in only a small number of studies. A case-crossover design was used to study 147,885 hospital admissions with renal diagnoses during July and August, 1991–2004, in New York State. Regional temperature, humidity, and barometric pressure data from automated monitors were used as exposure indicators. By use of time-stratified referent selection and conditional logistic regression analysis, an overall 9% increase in odds of hospitalization for acute renal failure per 5°F (2.78°C) was found for mean temperature at a 1-day lag (odds ratio = 1.09, 95% confidence interval: 1.07, 1.12). The results suggest increased susceptibility to hospitalization for acute renal failure for blacks, Hispanics, people aged 25–44 years, and those in the lowest income quartile. The odds varied geographically with the largest associations found in the more urban regions. Increased odds of hospitalization were also found for urinary tract infections, renal calculi, lower urinary calculi, and other lower urinary tract disorders. The findings can help to identify vulnerable subpopulations and to inform decisions and policies regarding adaptation strategies and heat-warning systems.