Extreme heat exposure correlates with increased risk of kidney disease-related ED visits
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Extreme heat exposure significantly correlated with a dose-dependent increased risk of kidney disease-related ED visits, according to data published in the American Journal of Kidney Diseases.
Further, extreme heat exposure in May or September yielded stronger associations with kidney disease-related ED visits than in summer months.
“Our findings underscore the alarming impact of ambient heat on ED visits of kidney diseases, especially the stronger impacts of heat in May and September in addition to summer. This study also highlights the need for improved physicians’ awareness, clinical preparedness and patient education to deal the anticipated rise of Medicare access as the result of climate change,” study co-author Shao Lin, MD, PhD, MPH, professor of public health at University of Albany, in New York, told Healio. “It is important for clinicians to counsel renal patients to be aware of the dangers of extreme heat exposure on their health and reduce outdoor exercise/activities and stay cool during extreme hot weather. Male and aging patients are more vulnerable to the adverse effect,” she added.
In a case-crossover study, researchers compared 1,114,322 ED visits with a primary diagnosis of kidney disease and extreme heat exposure. All visits occurred in New York between 2005 and 2013.
Weather data were derived from the EPA and the National Oceanic and Atmospheric Administration. Researchers identified weather patterns as extreme heat exposure when the daily temperature was hotter than the 90th percentile temperature of that month in the county.
Researchers considered extreme heat exposure immediately before patients visited the ED as case days. Control days occurred when patients did not visit the ED and were defined as the same days of the week in the same calendar month as the corresponding case day. Further, researchers examined the 7 days after case days to determine any lagging effects of heat.
Using a conditional logistic regression model while controlling for humidity, air pollutants and holidays, researchers compared the extreme heat exposure on case vs. control days. Results were stratified by sociodemographic characteristics.
Overall, extreme heat exposure significantly correlated with higher risk of kidney disease-related visits to the ED, with a 1.7% higher risk on lag day 0 and a 3.1% higher risk on lag day 2. Further, the correlation lasted for an entire week and was more prevalent in transitional months, like May and September, than summer months.
Researchers noted that patients with visits related to AKI, kidney stones and urinary tract infections were at a significantly increased risk.
“Early warning systems of extreme heat exposure may be considered not only in summer but also in transitional months. Preparation for the treatment of kidney disease during and after extreme heat exposure is recommended,” study co-author Yanji Qu, MD, PhD, a post-doctoral research fellow at the University of Albany, told Healio.
According to Lin, the team plans to continue this research by improving the exposure assessment with a refined temperature grid developed to link with residential addresses of patients. Additionally, researchers will expand the study population to include outpatient visits, hospital admissions and death due to renal diseases. Overall, further research will measure how weather factors affect kidney diseases, and Lin intends to work with policymakers to modify the current warning system to May or early summer.
Perspective
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Aneesha Shetty, MD, MPH, and Ryan C. Wong, MD
In the current era of extreme weather and global warming, the medical community is forced to think about the effect of environment factors on patients’ health. The article by Qu and colleagues explores the negative effect of extreme heat on increased kidney injury-related emergency room visits.
Arizona residents are familiar with excessive summer heat where temperatures regularly soar above 110°F. It is relatively common for patients to present with varying severities of AKI or even rhabdomyolysis from hypovolemia. In the most extreme cases, patients crossing the border in the summer months can experience severe kidney injury. In a 2012 publication by Ossai and colleagues, our institution cared for 42 patients with exertional rhabdomyolysis. The majority experienced stage 3 AKI, five required hemodialysis and eight were discharged with an abnormal creatinine.3
In addition, people who are not familiar with our climate can be at particularly high risk. Our institution also published the first case of exertional heat stroke and AKI in 1988 when a non-acclimated patient hiked the Grand Canyon further supporting the affect that rapid changes in environment can affect kidney health further supporting the effect of more emergency room visits during seasonal changes.4 It is important for those practicing in areas with extreme weather to consider how climate and weather can affect kidney health.
The environmental effects of extreme weather on kidney disease are essential to understand, particularly in vulnerable populations, like the oldest patients and kidney transplant recipients. Even mild acute kidney injury portends a two times higher risk of CKD and ESRD and 22% increased risk in hypertension.1,2
We often modulate diuretics, other antihypertensives and fluid restrictions based on season. We encourage kidney transplant recipients to increase their oral fluid intake according to the weather, often recommending more than 100 ounces of water intake per day to prevent dehydration due to extreme heat exposure. Educating patients regarding the impact of weather on their renal health and empowering them with the tools on how to protect themselves can help them regain some control of their health.
References:
1. Coca SG, et al. Kidney Int. 2022;doi:10.1038/ki.2011.379.
2. Hsu CY, et al. J Am Soc Nephrol. 2016;doi:10.1681/ASN.2014111114.
3. Ossai, N, et al. Ren Fail. 2013;doi:10.3109/0886022X.2013.774671
4. Pattison, ME, et al. Am J Kidney Dis. 1988;doi:10.1016/s0272-6386(88)80210-5.
5. Sasai F, et al. Nephrol Dial Transplant. 2021;doi:10.1093/ndt/gfab258.
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