Effects of diurnal variations in temperature on non-accidental mortality among the elderly population of Montreal, Québec, 1984–2007

Abstract

The association between short-term changes in ambient temperature and daily mortality has been described widely in the literature. A few recent papers support the hypothesis that diurnal variations in temperature may also have an impact on mortality, independent of the effect of daily mean temperature. The objective of the thesis was to determine whether variations in diurnal temperature increased daily non-accidental mortality among the elderly population of Montreal, Quebec, during the 1984-2007 study period. We used distributed lag non-linear models constrained over a 30 day lag period, and adjusted for temporal trends, mean daily temperature, and mean daily concentrations of nitrogen dioxide and ozone. We found over the 30 day lag period a cumulative increase of 5.12% (95% confidence interval (CI): 0.02 to 10.49) in daily mortality for an increase of the diurnal temperature range from 6 °C to 11 °C and a 11.27% (95% CI: 2.08 to 21.29) increase in mortality associated with an increase of the diurnal temperature range from 11 to 16 °C. The results were relatively robust to adjustment for mean temperature.In conclusion, we found that in Montreal daily diurnal variations in temperature are associated with a small increase in mortality among the elderly population. More studies are needed in different geographical locations to confirm these effects.ii Résumé L'association entre les variations à court terme de la température ambiante et la mortalité quotidienne a été largement décrite dans la littérature. Quelques articles récents supportent l'hypothèse que les variations diurnes de la température peuvent également avoir un impact notable sur la mortalité, indépendamment de l'effet de la température moyenne. L'objectif de la thèse était de déterminer si les variations de température diurne provoquent une augmentation de la mortalité quotidienne non accidentelle chez les iii

Impact of diurnal temperature range on mortality in a high plateau area in southwest China: A time series analysis

“…However, more than half of related previous studies assumed and demonstrated a linear relationship between DTR and mortality with evidence of increasing mortality with increasing DTR in different regions, including cities in China (Cao et al, 2009;Yang et al, 2013;Zhou et al, 2014) and Korea (Lim et al, 2012). In agreement with our findings, an elderly population in Montreal, Canada, showed a non-linear relationship between lag 0-30 days DTR and nonaccidental mortality (Vutcovici et al, 2014). Moreover, Luo et al (2013) found a U-shaped relationship between DTR and daily mortality in Guangzhou, China, claiming a stronger effect of higher and lower DTR than moderate DTR on mortality.…”

“…The effect of DTR on mortality has been studied in low altitude regions with low DTR (Holopainen et al, 2013;Lim et al, 2012;Yang et al, 2013;Zhou et al, 2014), but the effect of high DTR on mortality has been little studied (Luo et al, 2013;Vutcovici et al, 2014). To our knowledge, this is the first attempt to explore the effect of DTR on non-accidental, cardiorespiratory, cardiovascular and respiratory mortality in a high-altitude city in southwest China with a large range in daily temperature.…”

“…Most previous studies have shown that mortality risk depends on exposure to the current day's DTR and on the exposure experienced during several previous days ("lag" or delayed effects) (Braga et al, 2001;Guo et al, 2011;Vutcovici et al, 2014). Among time-series studies, the generalized additive model has been commonly used to quantify the effect of DTR on mortality and calculate the lag effects, because daily mortality counts typically follow the Poisson distribution and the effect of DTR on health is potentially nonlinear (Song et al, 2008).…”

“…The effect of DTR on mortality has been explored in China (Kan et al, 2007;Song et al, 2008;Zhou et al, 2014), Korea (Lim et al, 2013;Lim et al, 2012), Finland (Holopainen et al, 2013) and Canada (Vutcovici et al, 2014). However, most of the cities under study were highincome and located in low-altitude regions or coastal areas with low DTR.…”

Diurnal temperature range and short-term mortality in large US communities

“…A study examined DTR effects on elderly mortality in Canada and observed a cumulative 5 and 11 % increase in mortality due to increases in DTR from the 25th to the 75th and the 75th to the 99th percentile, respectively (Vutcovici et al 2013). The study area (Montreal, Canada) experienced relatively greater DTR (up to 28.1°C) than Asian regions (up to 16°C) (Kan et al 2007).…”