Health, UK (Commonwealth Union) – A recent study conducted by researchers at the University College London (UCL) and the London School of Hygiene & Tropical Medicine (LSHTM) reveals that chronic kidney disease patients residing in the hottest regions experience an additional 8% decline in kidney function annually compared to those in temperate climates.
Published in The Lancet Planetary Health, this study represents the first comprehensive global examination of the relationship between chronic kidney disease and heat over a medium-term period. The findings underscore the significant impact of heat on the health outcomes of kidney patients in warm climates, irrespective of the country’s economic status or other health factors like diabetes.
Chronic kidney disease (CKD), a condition characterized by various kidney ailments, typically results in a gradual deterioration of kidney function over time and affects approximately one in ten individuals worldwide. As kidney function declines to the point where it can no longer sustain life, patients necessitate kidney replacement therapy, such as dialysis or a kidney transplant.
Researchers of the study pointed out that although treating individuals with CKD is relatively inexpensive, kidney replacement therapies incur substantial costs and diminish the patient’s quality of life. Kidney failure alone consumes about 3 percent of the NHS budget, with dialysis averaging £30-40,000 per person annually. Presently, approximately 70,000 individuals in the UK undergo kidney replacement therapy, with dialysis and functioning kidney transplants accounting for 45 percent and 55 percent respectively.
It was further indicated that in less developed nations, access to these therapies is often limited, rendering kidney failure a fatal condition.
It’s long been recognized that individuals with CKD face greater challenges in many hot regions. However, determining if heat accelerates CKD progression has been challenging due to variations in underlying kidney disease rates, healthcare accessibility, and the necessity for standardized patient data collection during periods of stability.
In a recent study, researchers from UCL and LSHTM examined CKD clinical trial data from AstraZeneca, juxtaposing it with heat index data to evaluate whether heightened heat exposure correlates with changes in kidney function among CKD patients. This comprehensive analysis encompassed 4,017 individuals across 21 countries, reflecting diverse climates and a mix of middle- and high-income nations.
The findings revealed that individuals residing in extremely hot climates experienced an additional 8 percent decline in kidney function annually compared to those in temperate climates. Interestingly, this association persisted regardless of national income or the presence of risk factors such as obesity, hypertension, or diabetes among the patients.
Professor Ben Caplin, a senior author of the research conducted at the UCL Division of Medicine, indicated that they were, previously, aware that individuals with kidney disease experience poorer outcomes, particularly in numerous hot, economically disadvantaged nations globally. However, up until this point, it has been challenging to ascertain whether temperature and humidity significantly contribute to the progression of the disease, or if this is mitigated by factors such as access to quality healthcare, living conditions, dietary habits, diabetes, and various other variables.
“Our findings suggest that heat exposure itself, at levels experienced by individuals living in the hotter parts of the world, does cause kidney function to deteriorate more rapidly in those with pre-existing chronic kidney disease and to a degree that is meaningful for patients.
“Clearly, this is concerning given that the planet is getting hotter due to climate change. But now that the evidence suggests heat is important, we can test interventions to do something about it, whether this is through hydration, avoiding direct sun exposure or other measures to combat the effects of extreme heat.”
Since the study exclusively focused on patients with CKD, its findings lack applicability to understanding the correlation between heat and kidney function in individuals with normal renal function.
Professor Dorothea Nitsch, a senior researcher at the London School of Hygiene & Tropical Medicine and a lead author of the study, pointed out that the research encompassed hot countries spanning a spectrum of economic statuses, ranging from affluent nations like the US and Japan to middle-income nations like Vietnam. However, our observations weren’t explicable solely by GDP. Factors such as access to amenities like air conditioning and clean drinking water, crucial in mitigating heat’s impact, often remain beyond the reach of patients.”
The researchers of the study further indicated that heat across the world poses an escalating threat to humanity and the environment. The planet’s average surface temperature has surged by 1.1°C since the pre-Industrial era. Scientists emphasize the imperative to limit this increase to 1.5°C to sustain habitable conditions and avert catastrophic climate repercussions. Nevertheless, prevailing efforts to curb carbon emissions would result in a 3°C rise by the year 2100.
