A Russo

Vulnerability to Heat-Related Mortality: A Multicity, Population-Based, Case-Crossover Analysis

Background: Although studies have documented increased mortality during heat waves, little information is available on the subgroups most susceptible to these effects. We evaluated the effects of summertime high temperature on daily mortality among population subgroups defined by demographic characteristics, socioeconomic status, and episodes of hospitalization for various conditions during the preceding 2 years. Methods: We studied a total of 205,019 residents of 4 Italian cities (Bologna, Milan, Rome, and Turin) age 35 or older who died during 1997–2003. The case-crossover design was applied to evaluate the association between mean apparent temperature (same and previous day) and all-cause mortality. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) of dying at 30°C (apparent temperature) relative to 20°C were estimated accounting for time, population changes, and air pollution. Results: We found an overall OR of 1.34 (CI = 1.27–1.42) at 30°C relative to 20°C. The odds ratio increased with age and was higher among women (OR = 1.45; 1.37–1.52) and among widows and widowers (1.50; 1.33–1.69). Low area-based income modestly increased the effect. Among the preexisting medical conditions investigated, effect modification was detected for previous psychiatric disorders (1.69; 1.39–2.07), depression (1.72; 1.24–2.39), heart conduction disorders (1.77; 1.38–2.27), and circulatory disorders of the brain (1.47; 1.34–1.62). Temperature-related mortality was higher among people residing in nursing homes, and a large effect was also detected for hospitalized subjects. Conclusions: Subsets of the population that are particularly vulnerable to high summer temperatures include the elderly, women, widows and widowers, those with selected medical conditions, and those staying in nursing homes and healthcare facilities.

Impact of high temperatures on mortality: is there an added heat wave effect?

Background: Mortality during sustained periods of hot weather is generally regarded as being in excess of what would be predicted from smooth temperature-mortality gradients estimated using standard time-series regression models. However, the evidence for an effect of continuous days of exceptional heat (“heat wave effect”) is indirect. In addition, because some interventions may be triggered only during forecasted heat waves, it would be helpful to know what fraction of all heat-related deaths falls during these specific periods and what fraction occurs throughout the remainder of the summer. Methods: Extended time-series data sets of daily mortality counts in 3 major European cities (London, 28 years of data; Budapest, 31 years; Milan, 18 years) were examined in relation to hot weather using a generalized estimating equations approach. We modeled temperature and specific heat wave terms using a variety of specifications. Results: With a linear effect of same-day temperature above an identified threshold, an additional “heat wave” effect of 5.5% was observed in London (95% confidence interval = 2.2 to 8.9), 9.3% in Budapest (5.8 to 13.0), and 15.2% in Milan (5.7 to 22.5). Heat wave effects were reduced slightly when we relaxed the linear assumption and these effects were reduced substantially when temperature was modeled as an average value of lags 0 to 2 days. In London, fewer than half of all heat-related deaths could be attributed to identified heat wave periods. In Milan and Budapest, the fraction was less than one fifth. Conclusions: Heat wave effects were apparent in simple time-series models but were reduced in multilag nonlinear models and small when compared with the overall summertime mortality burden of heat. Reduction of the overall heat burden requires preventive measures in addition to those that target warnings and responses uniquely to heat waves.

Wheeze and asthma in children: associations with body mass index, sports, television viewing, and diet.

Background: Obesity, physical activity, and dietary habits are distinct but strongly interrelated lifestyle factors that may be relevant to the prevalence of wheeze and asthma in children. Our goal was to analyze the relationship of body mass index (BMI), regular sports participation, TV viewing, and diet with current wheezing and asthma. Methods: We investigated 20,016 children, aged 6–7 years, who were enrolled in a population-based study. Parents completed standardized questionnaires. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), while adjusting for several confounders and simultaneously considering BMI, regular sports activity, TV viewing and selected dietary items. Results: A total of 1575 children (7.9%) reported current wheezing and 1343 (6.7%) reported current asthma. In a multivariate model, an elevated BMI was associated with wheeze and current asthma: children from the highest quintile (compared with the lowest quintile) had an increased risk of wheeze (OR = 1.47; CI = 1.20–1.82) or current asthma (1.61; 1.28–2.01). Wheeze or asthma was not associated with regular sports activity. Subjects who spent 5 or more hours per day watching television were more likely to experience wheeze (1.53; 1.08–2.17) or current asthma (1.51; 1.04–2.2) compared with those who viewed TV less than 1 hour a day. Adding salt to food was strongly and independently associated with current wheeze (2.58; 1.41–4.71) and current asthma (2.68; 1.41–5.09). Conclusions: Our data support the hypothesis that high body weight, spending a lot of time watching television, and a salty diet each independently increase the risk of asthma symptoms in children.

Heat Waves in Italy: Cause Specific Mortality and the Role of Educational Level and Socio-Economic Conditions

Record temperatures were observed across Europe during the summer of 2003. Th ere is debate among experts as to whether the high temperatures observed in recent years are a normal fl uctuation in the climate or a sign of global warming characterized by wider temperature variations and an increase in climate extremes. Th e full impact of climate change on health still remains unclear, and an accurate analysis and quantifi cation of the possible eff ects, both in the short and long term, still has to be carried out (1,2). Although interest on the impact of heat on mortality is increasing, it is clear from summer 2003 that most European countries were unprepared to cope with this emergency. Th e relationship between weather, temperature and health has been well documented throughout the literature, both during the winter and summer seasons. Th e relationship between mortality and temperature graphically presents a “U” or “V” shape, with mortality rates lowest when the average temperature ranges between 15 – 25 °C and rising progressively as temperatures increase or decrease. In relation to hot weather and the eff ects of high temperatures on mortality, the literature has concentrated on the eff ect of extreme temperatures, oft en denoted as “heat waves”, which are known to enhance deaths from cardiovascular, cerebrovascular, and respiratory conditions (3,4). Th e increased frequency and intensity of heat waves may lead to an increase in heat-related deaths with the greatest impact on urban populations, particularly the elderly and the ill. Th e report presents an evaluation of the health impact of heat waves recorded during the summer of 2003 (June 1st – August 31st) in three major Italian cities (Rome, Milan and Turin). Th e analysis aims to analyse the impact of heat waves on cause-specifi c mortality and to analyse the role of demographic characteristics and socio-economic conditions that may increase the risk of mortality.