Skip to main navigation menu Skip to main content Skip to site footer
##common.pageHeaderLogo.altText##

Original article

Vol. 154 No. 10 (2024)

Vulnerability to heat-related mortality and the effect of prevention measures: a time-stratified case-crossover study in Switzerland

DOI
https://doi.org/10.57187/s.3418
Cite this as:
Swiss Med Wkly. 2024;154:3410
Published
01.10.2024

Summary

BACKGROUND: Swiss climate scenarios predict increases in the frequency and intensity of extreme heat episodes in the future. For the effective prevention of heat-related mortality, several aspects of the population’s vulnerability to heat must be understood on a local level.

METHODS: A nationwide analysis of individual death records was conducted, enabling a more comprehensive understanding than typical heat studies based on aggregated data. A total of 320,306 individual death records from the Swiss National Cohort with precise address information during the warm season (May to September) from 2003–2016 were linked to indoor and outdoor high-resolution daily temperature estimates. A time-stratified case-crossover study combined with distributed lag non-linear models was then performed to assess the temperature-mortality associations for various causes of death and to estimate the potential effect modification of individual characteristics. Additionally, it was explored whether the effect of extreme heat changed over time in regions with and without cantonal heat-health action plans (HHAPs).

RESULTS: Using the temperature with the lowest cause-specific mortality risk (minimum mortality temperature) as the reference temperature, extreme heat (defined as ambient daily maximum temperature reaching 33 °C) was associated with a strong increase in all-cause mortality (odds ratio (OR): 1.21, 95% CI: 1.17–1.25) and disease-specific mortality from Alzheimer’s disease and dementia (OR: 1.67, 95% CI: 1.48–1.88), COPD (OR: 1.37, 95% CI: 1.12–1.67), diabetes (OR: 1.34, 95% CI: 1.06–1.70), and myocardial infarction (OR: 1.26, 95% CI: 1.10–1.44). Indoor temperatures above 24 °C were found to be critical for mortality. The population most vulnerable to heat included older adults (≥75 years), unmarried individuals, people with a low education level, older women with low neighbourhood socioeconomic position, and men under 75 years old with low socioeconomic position. Overall, the risk of heat-related all-cause mortality in 2009–2016 was lower than that in 2003–2008. The decrease was significantly stronger in the region where cantonal HHAPs were implemented.

CONCLUSIONS: This study provides important information for planning targeted and effective measures to reduce heat-related health risks in Switzerland. It demonstrates that HHAPs contribute to reducing heat-related mortality, although they may not reach the high-risk population of individuals with low socioeconomic position. Future prevention efforts should also target the less privileged population, including people younger than 75 years.

References

  1. Federal Office for the Environment FOEN. Climate-related risks and opportunities. A synthesis for Switzerland – short version. Extended summary of the publication "Klimabedingte Risiken und Chancen. Eine schweizweite Synthese" www.bafu.admin.ch/uw-1706-d. Bern: Federal Office for the Environment FOEN, 2018.
  2. NCCS. CH2018 - Climate Scenarios for Switzerland. Zurich: National Centre for Climate Services (NCCS), 2018.
  3. Gasparrini A, Guo Y, Hashizume M, Lavigne E, Zanobetti A, Schwartz J, et al. Mortality risk attributable to high and low ambient temperature: a multicountry observational study. Lancet. 2015 Jul;386(9991):369–75. 10.1016/S0140-6736(14)62114-0
  4. Song X, Wang S, Hu Y, Yue M, Zhang T, Liu Y, et al. Impact of ambient temperature on morbidity and mortality: an overview of reviews. Sci Total Environ. 2017 May;586:241–54. 10.1016/j.scitotenv.2017.01.212
  5. Ragettli MS, Vicedo-Cabrera AM, Flückiger B, Röösli M. Impact of the warm summer 2015 on emergency hospital admissions in Switzerland. Environ Health. 2019 Aug;18(1):66. 10.1186/s12940-019-0507-1
  6. Ebi KL, Capon A, Berry P, Broderick C, de Dear R, Havenith G, et al. Hot weather and heat extremes: health risks. Lancet. 2021 Aug;398(10301):698–708. 10.1016/S0140-6736(21)01208-3
  7. Romanello M, Di Napoli C, Drummond P, Green C, Kennard H, Lampard P, et al. The 2022 report of the Lancet Countdown on health and climate change: health at the mercy of fossil fuels. Lancet. 2022 Nov;400(10363):1619–54. 10.1016/s0140-6736(22)01540-9 doi: https://doi.org/10.1016/S0140-6736(22)01540-9
  8. Ragettli MS, Röösli M. Die Bedeutung von Präventionsmassnahmen. Hitzebedingte Sterblichkeit im Sommer 2019. Prim Hosp Care. 2021;21(03):90–5. 10.4414/phc-d.2021.10296
  9. Vicedo-Cabrera AM, Ragettli MS, Schindler C, Röösli M. Excess mortality during the warm summer of 2015 in Switzerland. Swiss Med Wkly. 2016;146:w14379-w. doi: 10.4414/smw.2016.14379.
  10. Ragettli MS, Saucy A, Flückiger B, Vienneau D, de Hoogh K, Vicedo-Cabrera AM, et al. Explorative Assessment of the Temperature-Mortality Association to Support Health-Based Heat-Warning Thresholds: A National Case-Crossover Study in Switzerland. Int J Environ Res Public Health. 2023 Mar;20(6):4958. 10.3390/ijerph20064958
  11. Vicedo-Cabrera AM, de Schrijver E, Schumacher DL, Ragettli MS, Fischer EM, Seneviratne SI. The footprint of human-induced climate change on heat-related deaths in the summer of 2022 in Switzerland. Environ Res Lett. 2023 Jul;18(7):074037. 10.1088/1748-9326/ace0d0
  12. Vicedo-Cabrera AM, Scovronick N, Sera F, Royé D, Schneider R, Tobias A, et al. The burden of heat-related mortality attributable to recent human-induced climate change. Nat Clim Chang. 2021 Jun;11(6):492–500. 10.1038/s41558-021-01058-x
  13. Robine JM, Cheung SL, Le Roy S, Van Oyen H, Griffiths C, Michel JP, et al. Death toll exceeded 70,000 in Europe during the summer of 2003. C R Biol. 2008 Feb;331(2):171–8. 10.1016/j.crvi.2007.12.001
  14. Grize L, Huss A, Thommen O, Schindler C, Braun-Fahrländer C. Heat wave 2003 and mortality in Switzerland. Swiss Med Wkly. 2005 Apr;135(13-14):200–5. 10.4414/smw.2005.11009
  15. Martinez GS, Kendrovski V, Salazar MA, de’Donato F, Boeckmann M. Heat-health action planning in the WHO European Region: status and policy implications. Environ Res. 2022 Nov;214(Pt 1):113709. 10.1016/j.envres.2022.113709
  16. Kotharkar R, Ghosh A. Progress in extreme heat management and warning systems: A systematic review of heat-health action plans (1995-2020). Sustain Cities Soc. 2022;76:103487. 10.1016/j.scs.2021.103487
  17. Ragettli MS, Röösli M. [Heat-health action plans to prevent heat-related deaths-experiences from Switzerland]. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2019 May;62(5):605–11. 10.1007/s00103-019-02928-8
  18. Federal Office for the Environment FOEN. (2019). Hitze und Trockenheit im Sommer 2018. Auswirkungen auf Mensch und Umwelt: Umwelt-Zustand Nr. 1909. Bern, Federal Office for the Environment FOEN (FOEN) 1-91. [cited July 10, 2024]. Available from: https://www.nccs.admin.ch/dam/nccs/de/dokumente/website/sektoren/gesundheit/bafu-hitze-und-trockenheit-im-sommer-2018.pdf.download.pdf/Hitze%20und%20Trockenheit%20im%20Sommer%202018%20(BAFU,%202019)%20.pdf
  19. Murage P, Kovats S, Sarran C, Taylor J, McInnes R, Hajat S. What individual and neighbourhood-level factors increase the risk of heat-related mortality? A case-crossover study of over 185,000 deaths in London using high-resolution climate datasets. Environ Int. 2020 Jan;134:105292. 10.1016/j.envint.2019.105292
  20. Tham S, Thompson R, Landeg O, Murray KA, Waite T. Indoor temperature and health: a global systematic review. Public Health. 2020 Feb;179:9–17. 10.1016/j.puhe.2019.09.005
  21. Uejio CK, Tamerius JD, Vredenburg J, Asaeda G, Isaacs DA, Braun J, et al. Summer indoor heat exposure and respiratory and cardiovascular distress calls in New York City, NY, U.S. Indoor Air. 2016 Aug;26(4):594–604. 10.1111/ina.12227
  22. WHO Regional Office for Europe. Heat and health in the WHO European Region: updated evidence for effective prevention. Copenhagen: Word Health Organization (WHO). Europe. 2021.
  23. Hasan F, Marsia S, Patel K, Agrawal P, Razzak JA. Effective community-based interventions for the prevention and management of heat-related illnesses: a scoping review. Int J Environ Res Public Health. 2021 Aug;18(16):8362. 10.3390/ijerph18168362
  24. Spoerri A, Zwahlen M, Egger M, Bopp M. The Swiss National Cohort: a unique database for national and international researchers. Int J Public Health. 2010 Aug;55(4):239–42. 10.1007/s00038-010-0160-5
  25. Bopp M, Spoerri A, Zwahlen M, Gutzwiller F, Paccaud F, Braun-Fahrländer C, et al. Cohort Profile: the Swiss National Cohort—a longitudinal study of 6.8 million people. Int J Epidemiol. 2009 Apr;38(2):379–84. 10.1093/ije/dyn042
  26. Panczak R, Galobardes B, Voorpostel M, Spoerri A, Zwahlen M, Egger M; Swiss National Cohort and Swiss Household Panel. A Swiss neighbourhood index of socioeconomic position: development and association with mortality. J Epidemiol Community Health. 2012 Dec;66(12):1129–36. 10.1136/jech-2011-200699
  27. Ma Y, Zhou L, Chen K. Burden of cause-specific mortality attributable to heat and cold: A multicity time-series study in Jiangsu Province, China. Environ Int. 2020 Nov;144:105994. 10.1016/j.envint.2020.105994
  28. Flückiger B, Kloog I, Ragettli MS, Eeftens M, Röösli M, de Hoogh K. Modelling daily air temperature at a fine spatial resolution dealing with challenging meteorological phenomena and topography in Switzerland. Int J Climatol. 2022;42(12):1–16. 10.1002/joc.7597
  29. Ragettli MS, Vicedo-Cabrera AM, Schindler C, Röösli M. Exploring the association between heat and mortality in Switzerland between 1995 and 2013. Environ Res. 2017 Oct;158:703–9. 10.1016/j.envres.2017.07.021
  30. Koschenz M, Domingo-Irigoyen S, Niffeler M, Ragettli MS, Flückiger B, Kafadar M, et al. ResCool: Klimaanpassung von Neu-, Um-und bestehenden Wohnbauten – effiziente Kühlkonzepte. 2021 https://www.aramis.admin.ch/Default?DocumentID=68310&Load=true
  31. Maclure M. The case-crossover design: a method for studying transient effects on the risk of acute events. Am J Epidemiol. 1991 Jan;133(2):144–53. 10.1093/oxfordjournals.aje.a115853
  32. Janes H, Sheppard L, Lumley T. Case-crossover analyses of air pollution exposure data: referent selection strategies and their implications for bias. Epidemiology. 2005 Nov;16(6):717–26. 10.1097/01.ede.0000181315.18836.9d
  33. Gasparrini A. Distributed lag linear and non-linear models in R: the package dlnm. J Stat Softw. 2011 Jul;43(8):1–20. doi: https://doi.org/10.18637/jss.v043.i08
  34. Saucy A, Ragettli MS, Vienneau D, de Hoogh K, Tangermann L, Schäffer B, et al. The role of extreme temperature in cause-specific acute cardiovascular mortality in Switzerland: A case-crossover study. Sci Total Environ. 2021 Oct;790(147958):147958. 10.1016/j.scitotenv.2021.147958
  35. Gasparrini A, Guo Y, Hashizume M, Kinney PL, Petkova EP, Lavigne E, et al. Temporal variation in heat–mortality associations: a multicountry study. Environ Health Perspect. 2015 Nov;123(11):1200–7. 10.1289/ehp.1409070
  36. Tobías A, Hashizume M, Honda Y, Sera F, Ng CF, Kim Y, et al. Geographical variations of the minimum mortality temperature at a global scale: A multicountry study. Environ Epidemiol. 2021 Sep;5(5):e169. 10.1097/ee9.0000000000000169 doi: https://doi.org/10.1097/EE9.0000000000000169
  37. Gasparrini A. Extensions of the dlnm package: The Comprehensive R Archive Network; 2021 [cited 20 June]. Available from: https://cran.r-project.org/web/packages/dlnm/vignettes/dlnmExtended.pdf
  38. Martinez GS, Linares C, Ayuso A, Kendrovski V, Boeckmann M, Diaz J. Heat-health action plans in Europe: challenges ahead and how to tackle them. Environ Res. 2019 Sep;176:108548. 10.1016/j.envres.2019.108548
  39. Benmarhnia T, Bailey Z, Kaiser D, Auger N, King N, Kaufman JS. A difference-in-differences approach to assess the effect of a heat action plan on heat-related mortality, and differences in effectiveness according to sex, age, and socioeconomic status (Montreal, Quebec). Environ Health Perspect. 2016 Nov;124(11):1694–9. 10.1289/EHP203
  40. van Steen Y, Ntarladima AM, Grobbee R, Karssenberg D, Vaartjes I. Sex differences in mortality after heat waves: are elderly women at higher risk? Int Arch Occup Environ Health. 2019 Jan;92(1):37–48. 10.1007/s00420-018-1360-1
  41. Khraishah H, Alahmad B, Ostergard RL Jr, AlAshqar A, Albaghdadi M, Vellanki N, et al. Climate change and cardiovascular disease: implications for global health. Nat Rev Cardiol. 2022 Dec;19(12):798–812. 10.1038/s41569-022-00720-x
  42. Alahmad B, Khraishah H, Royé D, Vicedo-Cabrera AM, Guo Y, Papatheodorou SI, et al. Associations Between Extreme Temperatures and Cardiovascular Cause-Specific Mortality: Results From 27 Countries. Circulation. 2023 Jan;147(1):35–46. 10.1161/circulationaha.122.061832 doi: https://doi.org/10.1161/CIRCULATIONAHA.122.061832
  43. Schulte F, Röösli M, Ragettli MS. Heat-related cardiovascular morbidity and mortality in Switzerland: a clinical perspective. Swiss Med Wkly. 2021 Sep;151(3738):w30013. 10.4414/SMW.2021.w30013
  44. Xu Z, Tong S, Cheng J, Zhang Y, Wang N, Zhang Y, et al. Heatwaves, hospitalizations for Alzheimer’s disease, and postdischarge deaths: A population-based cohort study. Environ Res. 2019 Nov;178:108714. 10.1016/j.envres.2019.108714
  45. Gong J, Part C, Hajat S. Current and future burdens of heat-related dementia hospital admissions in England. Environ Int. 2022 Jan;159:107027. 10.1016/j.envint.2021.107027
  46. Bär S, Bundo M, de Schrijver E, Müller TJ, Vicedo-Cabrera AM. Suicides and ambient temperature in Switzerland: A nationwide time-series analysis. Swiss Med Wkly. 2022 Mar;152(910 w30115):w30115. 10.4414/smw.2022.w30115 doi: https://doi.org/10.4414/SMW.2022.w30115
  47. Kim Y, Kim H, Gasparrini A, Armstrong B, Honda Y, Chung Y, et al. Suicide and ambient temperature: a multi-country multi-city study. Environ Health Perspect. 2019 Nov;127(11):117007. 10.1289/EHP4898
  48. Vicedo-Cabrera AM, Sera F, Liu C, Armstrong B, Milojevic A, Guo Y, et al. Short term association between ozone and mortality: global two stage time series study in 406 locations in 20 countries. BMJ. 2020 Feb;368:m108. 10.1136/bmj.m108
  49. Buckley JP, Samet JM, Richardson DB. Commentary: does air pollution confound studies of temperature? Epidemiology. 2014 Mar;25(2):242–5. doi: https://doi.org/10.1097/EDE.0000000000000051

Most read articles by the same author(s)