Assessing the associations between daily ambient temperature variability and acute myocardial infarction and stroke in Norway

Abstract

Abstract - Background Climate change is considered one of the biggest threats to public health in our time. Climate change will likely affect both mean meteorological parameters and their variability, namely the frequency and magnitude of their fluctuations. A measurement of short-term temperature variability within one day, the diurnal temperature range (DTR), has increasingly been recognized as constituting a health threat due to the physiological stress it imposes on the human body (Bhaskaran et al., 2013; Khraishah et al., 2022). Investigating the DTR and its association with health outcomes will therefore improve our understanding of weather’s impact on public health and how this could change with climate change. This study examined the associations between DTR and the incidence of acute myocardial infarction (AMI) and between DTR and stroke in Norway. <p>

<p>Methods - Retrospective time series analyses with a quasi-Poisson regression model was conducted, using 134,370 incidences of AMI and 127,898 incidences of stroke to estimate the lagged and non-linear associations between DTR and AMI and DTR and stroke in Norway in the years 2008-2018. Subgroup analyses based on age groups were also conducted. <p>

<p>Main results - The findings revealed a significant non-linear association between high DTR and increased risk of AMI, more pronouncedly so among individuals aged 65 and above. The relative risks (RR) of having an AMI were found to be 1.16 (95% CI 1.01-1.33) for the overall population and 1.27 (95% CI 1.06-1.52) for those 65 years and older. These risks are associated with the 99th percentile (15.8 °C) compared to the 50th percentile (6.7 °C) of the DTR distribution. No association was found between DTR and stroke for the overall population or for the population 65 years and older. However, the risk of stroke was reduced centering around the 20 percentile (4.3 0C) with RR=0.86 (95% CI 0.74-0.99) and centering around the 94 percentile (12.9 0C) with RR=0.76 (95% CI 0.62-0.93) for the population younger than 65 years of age. <p>

<p>Conclusion - This study suggests that greater fluctuation in daily temperatures may exacerbate the risk of AMI in a developed, high latitude country like Norway, especially among the elderly population. This is despite Norway’s well-functioning health care system and the DTR being generally less than in larger parts of Europe. These findings underscore the importance of incorporating temperature variability into health planning and risk assessment strategies. Further research is needed to elucidate the mechanisms through which temperature variability affects cardiovascular health and to identify specific population subgroups at greater risk.