# Ambient temperature and the variability between neighbouring days impacts in-patient hospitalizations in the United Kingdom

## TL;DR

This study finds that temperature extremes and changes between days are linked to increased hospitalizations in the UK, especially for vulnerable populations.

## Contribution

The study quantifies the health impacts of temperature extremes and variability in temperate zones using UK hospitalization data.

## Key findings

- High temperatures during warm seasons increase hospitalizations for renal disease and heat-related illness.
- Cold-season high temperatures are linked to higher odds of cardiovascular and respiratory disease hospitalizations.
- People in deprived areas with less greenspace experience stronger temperature-related health effects.

## Abstract

Acute health effects of temperature extremes and variability in temperate zones has been rarely quantified. We examine the associations of ambient temperature and temperature change between neighbouring days with all-cause and cause-specific hospitalizations.

Daily hospital admission data were identified through hospital record linkage with UK Biobank, a cohort of half-a-million participants during 2006-2022. Temperature exposure was measured at 1×1 Km2 spatial resolution based on participants’ residential addresses. We used a time-stratified case-crossover design to examine short-term associations of ambient temperature and change in temperature between neighbouring days with all-cause and cause-specific hospitalizations.

We identify 709,052 warm-season hospitalizations and 676,686 cold-season hospitalizations. During warm season, high temperature cumulated over lag 0-3 days is associated with 9% [odds ratio (OR) = 1.09, 95% confidence interval (CI) = 1.02, 1.16] and 18% (OR = 1.18, 95% CI = 1.05, 1.34) higher odds of hospitalizations for renal disease and heat-related illness, respectively. During cold season, high temperature is associated with 4% (OR = 1.04, 95% CI = 1.01, 1.06) higher odds of overall hospitalizations from any cause, and also for cardiovascular disease (OR = 1.06, 95% CI = 1.02, 1.09), respiratory disease (OR = 1.05, 95% CI = 1.00, 1.11), mental disorders (OR = 1.08, 95% CI = 1.00, 1.16) and heat-related illness (OR = 1.25, 95% CI = 1.05, 1.48). We observe more pronounced associations between ambient temperature and overall hospitalization among subgroups residing in the most deprived neighbourhoods and with the least greenspace coverage during both warm and cold seasons.

Our findings suggest the need for multilevel mitigation and adaptation strategies for strengthening individual and urban resilience to minimize adverse health effects attributable to temperature extremes.

Temperatures are increasing globally. Information about the health impact of temperature extremes and its day-to-day variations can help inform climate mitigation and adaptation policies to improve health. We used 1.38 million hospitalization records from the UK and found there was an association between ambient temperature and all-cause and cause-specific hospitalizations, which varied by season. We also found more pronounced associations between ambient temperature and overall hospitalization among people living in the most deprived neighbourhoods and those with the least greenspace coverage during both warm and cold seasons. These findings could be used to inform targeted mitigation and adaptation strategies to improve health during temperature extremes.

Lai et al. use hospitalization records from the UK to examine associations between ambient temperature and changing temperature with all-cause and cause-specific hospitalizations. There is seasonal variation in associations with more pronounced effects in people living in deprived neighbourhoods and with low greenspace coverage.