Adrian G. Barnett

The impact of temperature on mortality in Tianjin, China: a case-crossover design with a distributed lag nonlinear model.

Background: Although interest in assessing the impacts of temperature on mortality has increased, few studies have used a case-crossover design to examine nonlinear and distributed lag effects of temperature on mortality. Additionally, little evidence is available on the temperature–mortality relationship in China or on what temperature measure is the best predictor of mortality. Objectives: Our objectives were to use a distributed lag nonlinear model (DLNM) as a part of case-crossover design to examine the nonlinear and distributed lag effects of temperature on mortality in Tianjin, China and to explore which temperature measure is the best predictor of mortality. Methods: We applied the DLNM to a case-crossover design to assess the nonlinear and delayed effects of temperatures (maximum, mean, and minimum) on deaths (nonaccidental, cardiopulmonary, cardiovascular, and respiratory). Results: A U-shaped relationship was found consistently between temperature and mortality. Cold effects (i.e., significantly increased mortality associated with low temperatures) were delayed by 3 days and persisted for 10 days. Hot effects (i.e., significantly increased mortality associated with high temperatures) were acute and lasted for 3 days and were followed by mortality displacement for nonaccidental, cardiopulmonary, and cardiovascular deaths. Mean temperature was a better predictor of mortality (based on model fit) than maximum or minimum temperature. Conclusions: In Tianjin, extreme cold and hot temperatures increased the risk of mortality. The effects of cold last longer than the effects of heat. Combining the DLNM and the case-crossover design allows the case-crossover design to flexibly estimate the nonlinear and delayed effects of temperature (or air pollution) while controlling for season.

The effects of air pollution on hospitalizations for cardiovascular disease in elderly people in Australian and New Zealand cities.

Objective The goal of this study was to estimate the associations between outdoor air pollution and cardiovascular hospital admissions for the elderly Design Associations were assessed using the case–crossover method for seven cities: Auckland and Christchurch, New Zealand; and Brisbane, Canberra, Melbourne, Perth, and Sydney Australia. Results were combined across cities using a random-effects meta-analysis and stratified for two adult age groups: 15–64 years and ≥ 65 years of age (elderly). Pollutants considered were nitrogen dioxide, carbon monoxide, daily measures of particulate matter (PM) and ozone. Where multiple pollutant associations were found, a matched case–control analysis was used to identify the most consistent association. Results In the elderly, all pollutants except O3 were significantly associated with five categories of cardiovascular disease admissions. No associations were found for arrhythmia and stroke. For a 0.9-ppm increase in CO, there were significant increases in elderly hospital admissions for total cardiovascular disease (2.2%), all cardiac disease (2.8%), cardiac failure (6.0%), ischemic heart disease (2.3%), and myocardial infarction (2.9%). There was some heterogeneity between cities, possibly due to differences in humidity and the percentage of elderly people. In matched analyses, CO had the most consistent association. Conclusions The results suggest that air pollution arising from common emission sources for CO, NO2, and PM (e.g., motor vehicle exhausts) has significant associations with adult cardiovascular hospital admissions, especially in the elderly, at air pollution concentrations below normal health guidelines. Relevance to clinical and professional practice Elderly populations in Australia need to be protected from air pollution arising from outdoor sources to reduce cardiovascular disease.

What measure of temperature is the best predictor of mortality

Hot and cold temperatures significantly increase mortality rates around the world, but which measure of temperature is the best predictor of mortality is not known. We used mortality data from 107 US cities for the years 1987-2000 and examined the association between temperature and mortality using Poisson regression and modelled a non-linear temperature effect and a non-linear lag structure. We examined mean, minimum and maximum temperature with and without humidity, and apparent temperature and the Humidex. The best measure was defined as that with the minimum cross-validated residual. We found large differences in the best temperature measure between age groups, seasons and cities, and there was no one temperature measure that was superior to the others. The strong correlation between different measures of temperature means that, on average, they have the same predictive ability. The best temperature measure for new studies can be chosen based on practical concerns, such as choosing the measure with the least amount of missing data.

Cold periods and coronary events: an analysis of populations worldwide.

Study objective: To investigate the association between cold periods and coronary events, and the extent to which climate, sex, age, and previous cardiac history increase risk during cold weather. Design: A hierarchical analyses of populations from the World Health Organisation’s MONICA project. Setting: Twenty four populations from the WHO’s MONICA project, a 21 country register made between 1980 and 1995. Patients: People aged 35–64 years who had a coronary event. Main results: Daily rates of coronary events were correlated with the average temperature over the current and previous three days. In cold periods, coronary event rates increased more in populations living in warm climates than in populations living in cold climates, where the increases were slight. The increase was greater in women than in men, especially in warm climates. On average, the odds for women having an event in the cold periods were 1.07 higher than the odds for men (95% posterior interval: 1.03 to 1.11). The effects of cold periods were similar in those with and without a history of a previous myocardial infarction. Conclusions: Rates of coronary events increased during comparatively cold periods, especially in warm climates. The smaller increases in colder climates suggest that some events in warmer climates are preventable. It is suggested that people living in warm climates, particularly women, should keep warm on cold days.

Oxygen delivery through high-flow nasal cannulae increase end-expiratory lung volume and reduce respiratory rate in post-cardiac surgical patients.

BACKGROUND High-flow nasal cannulae (HFNCs) create positive oropharyngeal airway pressure, but it is unclear how their use affects lung volume. Electrical impedance tomography allows the assessment of changes in lung volume by measuring changes in lung impedance. Primary objectives were to investigate the effects of HFNC on airway pressure (P(aw)) and end-expiratory lung volume (EELV) and to identify any correlation between the two. Secondary objectives were to investigate the effects of HFNC on respiratory rate, dyspnoea, tidal volume, and oxygenation; and the interaction between BMI and EELV. METHODS Twenty patients prescribed HFNC post-cardiac surgery were investigated. Impedance measures, P(aw), ratio, respiratory rate, and modified Borg scores were recorded first on low-flow oxygen and then on HFNC. RESULTS A strong and significant correlation existed between P(aw) and end-expiratory lung impedance (EELI) (r=0.7, P<0.001). Compared with low-flow oxygen, HFNC significantly increased EELI by 25.6% [95% confidence interval (CI) 24.3, 26.9] and P(aw) by 3.0 cm H(2)O (95% CI 2.4, 3.7). Respiratory rate reduced by 3.4 bpm (95% CI 1.7, 5.2) with HFNC use, tidal impedance variation increased by 10.5% (95% CI 6.1, 18.3), and ratio improved by 30.6 mm Hg (95% CI 17.9, 43.3). A trend towards HFNC improving subjective dyspnoea scoring (P=0.023) was found. Increases in EELI were significantly influenced by BMI, with larger increases associated with higher BMIs (P<0.001). CONCLUSIONS This study suggests that HFNCs reduce respiratory rate and improve oxygenation by increasing both EELV and tidal volume and are most beneficial in patients with higher BMIs.

Projecting future heat-related mortality under climate change scenarios: a systematic review.

Background: Heat-related mortality is a matter of great public health concern, especially in the light of climate change. Although many studies have found associations between high temperatures and mortality, more research is needed to project the future impacts of climate change on heat-related mortality. Objectives: We conducted a systematic review of research and methods for projecting future heat-related mortality under climate change scenarios. Data sources and extraction: A literature search was conducted in August 2010, using the electronic databases PubMed, Scopus, ScienceDirect, ProQuest, and Web of Science. The search was limited to peer-reviewed journal articles published in English from January 1980 through July 2010. Data synthesis: Fourteen studies fulfilled the inclusion criteria. Most projections showed that climate change would result in a substantial increase in heat-related mortality. Projecting heat-related mortality requires understanding historical temperature–mortality relationships and considering the future changes in climate, population, and acclimatization. Further research is needed to provide a stronger theoretical framework for projections, including a better understanding of socioeconomic development, adaptation strategies, land-use patterns, air pollution, and mortality displacement. Conclusions: Scenario-based projection research will meaningfully contribute to assessing and managing the potential impacts of climate change on heat-related mortality.

Longing to belong: Social inclusion and wellbeing among youth with refugee backgrounds in the first three years in Melbourne, Australia

For young people with refugee backgrounds, establishing a sense of belonging to their family and community, and to their country of resettlement is essential for wellbeing. This paper describes the psychosocial factors associated with subjective health and wellbeing outcomes among a cohort of 97 refugee youth (aged 11-19) during their first three years in Melbourne, Australia. The findings reported here are drawn from the Good Starts Study, a longitudinal investigation of settlement and wellbeing among refugee youth conducted between 2004 and 2008. The overall aim of Good Starts was to identify the psychosocial factors that assist youth with refugee backgrounds in making a good start in their new country. A particular focus was on key transitions: from pre-arrival to Australia, from the language school to mainstream school, and from mainstream school to higher education or to the workforce. Good Starts used a mix of both method and theory from anthropology and social epidemiology. Using standardized measures of wellbeing and generalised estimating equations to model the predictors of wellbeing over time, this paper reports that key factors strongly associated with wellbeing outcomes are those that can be described as indicators of belonging - the most important being subjective social status in the broader Australian community, perceived discrimination and bullying. We argue that settlement specific policies and programs can ultimately be effective if embedded within a broader socially inclusive society - one that offers real opportunities for youth with refugee backgrounds to flourish.

Advanced paternal age is associated with impaired neurocognitive outcomes during infancy and childhood

Background Advanced paternal age (APA) is associated with an increased risk of neurodevelopmental disorders such as autism and schizophrenia, as well as with dyslexia and reduced intelligence. The aim of this study was to examine the relationship between paternal age and performance on neurocognitive measures during infancy and childhood. Methods and Findings A sample of singleton children (n = 33,437) was drawn from the US Collaborative Perinatal Project. The outcome measures were assessed at 8 mo, 4 y, and 7 y (Bayley scales, Stanford Binet Intelligence Scale, Graham-Ernhart Block Sort Test, Wechsler Intelligence Scale for Children, Wide Range Achievement Test). The main analyses examined the relationship between neurocognitive measures and paternal or maternal age when adjusted for potential confounding factors. Advanced paternal age showed significant associations with poorer scores on all of the neurocognitive measures apart from the Bayley Motor score. The findings were broadly consistent in direction and effect size at all three ages. In contrast, advanced maternal age was generally associated with better scores on these same measures. Conclusions The offspring of older fathers show subtle impairments on tests of neurocognitive ability during infancy and childhood. In light of secular trends related to delayed fatherhood, the clinical implications and the mechanisms underlying these findings warrant closer scrutiny.

Temperature and Cardiovascular Deaths in the US Elderly: Changes Over Time

Background: Short-term changes in temperature have been associated with cardiovascular deaths. This study examines changes in this association over time among the US elderly. Methods: Daily cardiovascular mortality counts from 107 cities in the US National Morbidity and Mortality Air Pollution Study were regressed against daily temperature using the case-crossover method. Estimates were averaged by time and season using a meta-analysis. Results: In summer 1987 the average increase in cardiovascular deaths due to a 10°F increase in temperature was 4.7%. By summer 2000, the risk with higher temperature had disappeared (−0.4%). In contrast, an increase in temperature in fall, winter and spring was associated with a decrease in deaths, and this decrease remained constant over time. Conclusions: Heat-related cardiovascular deaths in the elderly have declined over time, probably due to increased use of air conditioning, while increased risks with cold-related temperature persist.

Evaluation of two time-specific back pain outcome measures.

STUDY DESIGN Postal questionnaire to individuals with back pain. OBJECTIVE To assess the acceptability, validity, and reliability of two existing back pain outcome measures, the Roland-Morris Questionnaire and the Von Korff scales, modified to measure the preceding 4 weeks. SUMMARY OF BACKGROUND DATA The ideal outcome measure for studies of low back pain and disability remains elusive. Most existing measures assess current pain and disability. Measuring these factors over a preceding 4-week period may be more appropriate. METHODS Individuals with back pain identified in a community survey were asked to complete the modified questionnaires. Validity was assessed by comparison with the Medical Outcome Study Short Form 36 and two general comparator questions on self-reported pain and disability. Repeatability was assessed using retest questionnaires. RESULTS Completed questionnaires were returned by 95 individuals with chronic back pain. The modified Roland-Morris Questionnaire and Von Korff pain and Von Korff disability scales were completed satisfactorily by 83 (87%), 89 (94%), and 87 (92%) participants, respectively. Mean scores of the modified measures changed significantly and in a predictable manner with increasing ratings of pain and disability. They also correlated with aspects of the Medical Outcome Study Short Form 36 questionnaire. Retest data suggest that these measures are repeatable. The modified Roland-Morris Questionnaire provided adequate analyzable data only if missing values were imputed, and it explained less of the variance in the comparator questions than the modified Von Korff scales. CONCLUSIONS The modified Von Korff scales were completed easily and appear to be valid and repeatable in this format.