The study finds no evidence that mild Covid-19 causes long-term kidney damage

The study finds no evidence that mild Covid-19 causes long-term kidney damage

A new study of over 13 million people in England has found no evidence that a mild Covid-19 infection can cause long-term kidney damage. However, patients hospitalized with severe Covid-19 infections are at high risk of long-term kidney damage, the analysis shows.

Over the course of the Covid-19 pandemic, severe infections requiring hospitalization have often been accompanied by a decline in kidney function. While research studies continue to support this association, it has remained unclear whether milder Covid-19 infections that do not require hospital treatment can also affect kidney function in the long term.

The new study, led by researchers at the London School of Hygiene & Tropical Medicine (LSHTM), as part of the Openensafely collaboration with the University of Oxford, analyzed electronic health data from over 13 million GP and hospital records in England between February 1, 2020 and December 31, 2022.

The OpenSafely platform acts as a gateway between electronic health records and important medical research. The platform, developed over the Covid-19 pandemic, allows information from GP records to be anonymised, aggregated with other data sources such as hospital records and used in scientific studies, without researchers having direct access to the records or identifiable information.

Of the data analyzed in the study, over 3.5 million people were recorded with Covid-19 infection, and 10 million people had no infection records. Records of people who were already on dialysis, a treatment that leaves a patient's kidneys unable to do so, or living with a kidney transplant were excluded from the sample.

The results will be published inThe Lancet Regional Health Europe.

During the study period, people who required hospitalization for Covid-19 were over seven times more likely to develop kidney failure than people without Covid-19. These risks were higher among those who were intensive and in those who had an acute kidney injury during their illness. There was no increased risk of kidney failure in people with Covid-19 that was not severe enough to require hospitalization.

Dr. Viyaasan Mahalingasivam, a research fellow at LSHTM and a specialist kidney doctor at Barts Health NHS Trust, said: “Our study is the largest of its kind to look at the long-term effects of Covid-19 infections resulting from Heightemmema-1 severe kidney injury.

"It is reassuring that we have found no evidence that mild Covid-19 infection causes long-term damage to kidney function. However, we cannot ignore that those who have severe illness with Covid-19 and end up in hospital are at high risk of kidney failure or worsening kidney function.

"Our work builds on previous studies indicating that kidney complications following Covid-19 may be a greater problem than other types of infections. However, we cannot say whether the main mechanism behind this is the Covid-19 virus directly attacking the kidney or whether it is a consequence of the body's high-inflammatory infection attacking it."

The study also found that the increased risk of kidney damage among patients hospitalized with COVID-19 infections varied across ethnicities and was highest for black ethnic groups.

Our results show that a mild Covid-19 infection does not increase your risk of developing long-term kidney damage, and this is particularly reassuring for patients already living with kidney disease. However, there were still a significant number of people hospitalized for Covid-19 infections who then developed kidney failure, and it is important that we try to determine how we can minimize this in the future.

Our findings add to growing calls for more studies on health inequalities and what might be driving them, e.g.

Dr. Laurie Tomlinson, professor of clinical epidemiology at LSHTM and senior author of the study

The authors say health care providers should prioritize interventions that minimize the likelihood of vulnerable groups requiring hospitalization. This includes ensuring vaccinations can be reached to patients most vulnerable to serious illness. They say patients discharged from hospital after treatment for CoVID-19 infection should also be carefully monitored.

The research was funded by the National Institute for Health and Care Research.

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