High Temperatures Linked to Increase in Drug and Alcohol-Related Hospital Visits

Rising hospital visits for alcohol- and substance-related disorders are being driven by warm weather, a new study has found.

Published in Communications Medicine, the researchers warn that this relationship could be further affected by climate change, as global average temperatures continue to rise.

Weather and substance use – an underexplored relationship

Periods of extreme cold and heat are already a significant issue for public health, as illustrated by heatstroke and other weather-related illnesses. However, significant temperature changes can also exert pressure on other areas of public health.

Drug and alcohol use is a major focus for public health research and intervention, with substance misuse resulting directly and indirectly in hundreds of thousands of excess deaths per year. While most studies to date have looked at the impacts of climate change on health with respect to infectious disease and chronic health conditions, researchers say there are many plausible reasons why weather changes might also affect substance use.

“First, higher temperatures may potentially increase riskier outdoor activities,” first author Robbie M. Parks, PhD, assistant professor of environmental health sciences at Columbia University's Mailman School of Public Health, told Technology Networks. “Second, rising temperatures could increase rates of consumption of substances. Third, rising temperatures could result in more dehydration. Fourth, rising temperatures could result in driving under the influence. All of which may explain why someone may end up in hospital for alcohol- and other substance-related reasons in hotter weather.”

To get a better understanding of how temperature might affect drug and alcohol use, Parks and colleagues conducted what they believe to be the first comprehensive investigation of the association between temperature and hospital visits for alcohol- and drug-related disorders.

Higher temperatures result in increased hospitalizations for drug-related disorders

The new study implements a case-crossover design, controlling for seasonal variation and long-term trends, that compared weather data recorded at different ZIP codes around New York State and alcohol and substance-related disorder hospital visits from 1995–2014. This included data from more than 670,000 alcohol-related and 720,000 drug-related disorder hospital visits, alongside local temperature and relative humidity records.

Using a statistical model, the researchers compared days with notably high temperatures against nearby days with lower temperatures. This allowed them to understand the impact of short-term climate phenomena, such as small heatwaves, on hospital visits.

They found that when temperatures were high, this resulted in a near-linear increase in the number of alcohol-related hospital visits. Increasing temperatures from the daily mean up to the 90^th percentile (around 23 °C) was associated with a cumulative 25.6% increase in hospital visits.

For substance-related disorders, a similar near-linear association was also found for increases from the minimum temperatures up to the 75^th percentile (18.8 °C), but not beyond.

The researchers say that these increase patterns might be due to warmer weather encouraging more risky behaviors, dehydration, time outdoors and other risk factors that could contribute to a need for hospitalization. This could also explain why the increases fall off past a certain temperature, as perhaps above a certain temperature people are no more likely to go outside.

In their paper, the authors also caution that their study may actually be underestimating the association between temperature rises and hospital visits linked to substance use disorders, as the most severe cases of drug overdose may have resulted in deaths before a hospital visit was possible. This is something that the authors say could be addressed in future research.

A warming climate brings new risks

In recent decades, rates of heavy episodic drinking and alcohol-related deaths have been rising in the United States. Drug overdose deaths have also increased more than five-fold since the end of the 20^th century.

Examining how environmental factors, such as periods of hot weather, affect rates of alcohol and drug-related hospitalizations can help public health officials construct awareness campaigns that address these added risks, the researchers say.

“Public health interventions could involve information campaigns during periods of hot weather explaining the risks of consuming psychoactive substances, and reminders to particularly keep hydrated and out of direct sunlight,” Parks suggested.

In addition to informing proactive policies that could help protect vulnerable communities during periods of hot weather, the researchers also believe their results hint at a less obvious potential consequence of climate change.

“Really this study is one of several to highlight potentially understudied links between climate change and public health, highlighting how widespread the impacts of rising temperatures are on health,” Parks said.

Reference: Parks RM, Rowland ST, Do V, et al. The association between temperature and alcohol- and substance-related disorder hospital visits in New York State. Commun Med. 2023;3(1):1-9. doi: 10.1038/s43856-023-00346-1

Robbie M. Parks was speaking to Alexander Beadle, Science Writer for Technology Networks.