The interplay between climate change and ageing: A systematic review of health indicators

severity worsening drought periods in the western United States of America (USA), i.e., at least 150 days period where drought conditions were the same or worse than the previous day [38]. A study in Japan also reported a 0.5% (95% CI: 0.1–1.0) increase in mortality per 1-unit increase in the temperature deviation index (TDI) [42]. Also related to temperature, one study found that each 2.5% increase in death rate corresponded to a 1˚C increase in summer mean temperature [48]. ENSO variability, the irregular periodic variation of meteorological conditions over the tropic Pacific Ocean, also impacts non-accidental all-cause mortality risks. Extremely low and high levels of ENSO were both associated with increased mortality risks [52]. Meanwhile, one article focused on cause-specific mortality. This study investigated the correlation between heart failure-related deaths and daily temperature in Canada. It was reported that the risk of heart failure death or hospitalization increased by about 0.7% for each decrease of 1˚C in the mean daily temperature in the previous 3 (RR 0.994, 95% CI: 0.992– 0.996) or 7 days (RR 0.993, 95% CI: 0.991–0.995) [51]. Table 1. (Continued) Authors, Year Study Design Country (Data Collection Years) Climate Change Phenomenon Health Outcome Indicators Morbidity Mortality Vanasse et al., 2017 [51] Retrospective cohort study Canada (2001–2011) Mean daily T increase (lag-day 3 or 7) Hospitalizations and deaths due HF The risk of HF events (death or hospitalization) increased by about 0.7% for each decrease of 1˚C in the mean daily T in both

lag-day 3 (RR 0.994, 95% CI: 0.992–0.996) and lag-day 7 (RR 0.993, 95% CI: 0.991–0.995). Wei et al., 2019 [10] Prospective cohort study USA (2001– 2011) Mean and variability of summer and winter T Hospitalizations for dementia An increase in summer mean T was associated with a 12% (95% CI: 1.09–1.15) increase in the risk of hospitalization. There was a significant increase in the risk of hospitalization per 0.5˚C increase in variability of summer T (HR = 1.07; 95% CI: 1.05–1.09). NA Xu et al., 2022 [52] Retrospective cohort study China (1998– 2018) Extreme ENSO conditions Non-accidental all-cause mortality NA Extremely low and high levels of ENSO over lags of 0–12 months were associated with increased mortality risks. Zheng et al., 2016 [53] Ecological study China (2009– 2011) DTR ER admissions for cardiovascular disease (all- cause cardiovascular disease, ischemic heart disease and cerebrovascular disease) A 1˚C increase in DTR corresponded to a 1.46% (95% CI: 0.74–2.19) increase in all cardiovascular diseases, a 1.71% (0.21–3.23) increase in ischemic heart disease and a 1.55% (0.19– 2.93) in cerebrovascular disease among females (2-day lag effects). A 1˚C increase in DTR corresponded to 1.13% (95% CI: 0.11–2.16) increase in all cardiovascular diseases and a 2.13 (0.51–3.77) in cerebrovascular disease among males (4-day lag effects). NA AKI = acute kidney injury; AMI = acute myocardial infarction; AMO = Atlantic Multidecadal Oscillation; CI = confidence interval; COPD = chronic obstructive

pulmonary disease; DTR = diurnal temperature range; EH = extreme heat; ENSO = El Niño-southern Oscillation; ER = emergency room; HF = heart failure; HR = hazard ratio; IDH = ischemic heart disease; NA = not applicable; OR = odds ratio; PI = prediction interval; RR = relative risk; SST = sea surface temperature; T = temperature(s); TDI = temperature deviation index; USA = United States of America; vs. = versus. (Only statistically significant results were presented) https://doi.org/10.1371/journal.pone.0297116.t001 PLOS ONE Climate change, ageing and health PLOS ONE | https://doi.org/10.1371/journal.pone.0297116 April 24, 2024 9 / 17