A Systematic Review and Meta-Analysis on the Relationships between Extreme Ambient Temperature and All-Cause Mortality Risk: A Time Series Approach

Background: Exposure to extreme low or high ambient temperatures is associated with cardiovascular, respiratory and endocrine diseases and other complications, thereby causing death. This article is a synthesis of the relationships between ambient temperature and mortality from time series studies.

Methods: This systematic review and meta-analysis used the PICO search strategy and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. On 14th February to 21st of May 2020, PubMed, Springer and Science direct databases were systematically searched to obtain original studies published during the period of (2010 to 2019). The systematic review incorporated 23 studies, with sixteen (16) of these articles used for the meta-analysis and the remaining seven (7) articles were included in the narrative synthesis. Twelve of 16 studies used for meta-analysis were conducted in countries in Asia particularly in China, while three (3) of the remaining in Europe (Sweden, Spain and Portugal) and only one (1) study in Africa (South Africa). The meta-analysis was sub-grouped into (cold and warm) temperatures.

Results: The result of the meta-analysis indicated a pooled relative risk (RR) for cold temperature of 1.632, while pooled RR for the warm temperature of 1.287 and the RR for the whole data (cold and warm) temperature of 1.430. The Meta-analysis indicated a statistical significance (p < 0.01) of the pooled estimate which signified that exposure to cold or extreme low temperature 1.632 (95% CI 1.262–2.110) have greater mortality risk than exposure to extreme high temperature 1.287 (95% CI 1.030–1.606).

Conclusion: The RRs for extreme low and high temperatures associated with temperature attributable deaths differs in populations and locality. Government, Decision Makers, Social Actors and Health Administrators should make adequate planning and set up public health interventions to prevent and control the health impact of exposure to extreme ambient temperatures in vulnerable subpopulation particularly Africa.