Effect of Ambient Temperature on Australian Northern Territory Public Hospital Admissions for Cardiovascular Disease among Indigenous and Non-Indigenous Populations

Abstract

Hospitalisations are associated with ambient temperature, but little is known about responses in population sub-groups. In this study, heat responses for Indigenous and non-Indigenous people in two age groups were examined for two categories of cardiac diseases using daily hospital admissions from five Northern Territory hospitals (1992–2011). Admission rates during the hottest five per cent of days and the coolest five per cent of days were compared with rates at other times. Among 25–64 year olds, the Indigenous female population was more adversely affected by very hot days than the non-Indigenous female population, with admission rates for ischaemic heart disease (IHD) increasing by 32%. People older than 65 were more sensitive to cold, with non-Indigenous male admissions for heart failure increasing by 64%, and for IHD by 29%. For older Indigenous males, IHD admissions increased by 52% during cold conditions. For older non-Indigenous females, increases in admissions for heart failure were around 50% on these cold days, and 64% for older Indigenous females. We conclude that under projected climate change conditions, admissions for IHD amongst younger Indigenous people would increase in hot conditions, while admissions among elderly people during cold weather may be reduced. The responses to temperature, while showing significant relationships across the Northern Territory, may vary by region. These variations were not explored in this assessment.

Impact of climate conditions on hospital admissions for subcategories of cardiovascular diseases

“…Another interesting result of this study is that the number of the IHD admissions is reduced on days with higher temperature. Similarly, an increased rate of all the CVD admissions as a response to cold weather conditions was reported among the elderly as well as the reduction in admissions on very hot days [13]. The association of the CVD admissions with temperature supports the hypothesis that it is likely, that the elderly were more exposed to outside activities on days with lower temperature than on warmer days.…”

“…Cold weather conditions have been shown to have a stronger influence on increasing morbidity associated with heart failure, as compared to the morbidity associated with the IHD [13]. However, our results confirmed the strongly significant association between the IHD admissions and lower temperature among the elderly, adjusted to the relative humidity and air pressure.…”

“…On the other hand, one European study did not find a significant association between temperature and the whole group of the CVD and cerebrovascular admissions [8]. These disease-specific subcategories are not affected solely by the change of weather but are also age dependent, as indicated by the studies conducted in Slovenia and Australia [12,13].…”

Comparative evaluation of human heat stress indices on selected hospital admissions in Sydney, Australia

“…Hyperthermia – elevated core body temperature – is caused when the heat produced by a person's m etabolism or received from external sources can no longer be dispersed 4 . The effects of heat stress on populations are regularly modelled by epidemiologists: heat extremes are typically linked with increased incidences in respiratory and renal conditions, 5 as well as cardiovascular conditions 6–8 …”

Temperature and Humidity Effects on Hospital Morbidity in Darwin, Australia

“…28 Admissions were filtered by the principal diagnosis or any secondary diagnoses using criteria developed in personal communications with Peter Tait based on a previous study (2014) 29 : Diagnoses with an existing epidemiologic link to temperature and a physiologic basis that were also prevalent in the NT. A limited number of cases with diagnoses that directly stated heat or sunlight exposure were selected, although these cases represented a negligible fraction of the total, as illustrated by Table 1.…”