Influenza A patients at double kidney injury risk compared to Covid-19 

A recent study conducted by the LKS Faculty of Medicine, University of Hong Kong HKUMed researchers, published in eClinical Medicine, reveals that critically ill patients with influenza A have nearly double the risk of developing acute kidney injury (AKI) compared to those with COVID-19.

Analyzing data from a Hong Kong-wide cohort, the study found that critically ill patients with influenza A have a 49pc higher risk of AKI than those with Covid-19. Additionally, influenza A patients showed a 43pc higher risk of developing stage 3 AKI and a 48pc increased need for acute dialysis.

“These findings sharply contrast with previous reports that suggested a higher risk of AKI in Covid-19 patients. Our study offers new insights into the differing impacts of these respiratory viruses on kidney health,” said Dr. Desmond Yap Yat-hin, Associate Professor in the Department of Medicine at HKUMed and lead researcher.

Both SARS-CoV-2 and influenza A are known to cause severe respiratory infections that can lead to complications like AKI. However, comparative research on AKI incidence and severity between these viruses has been limited. This study addresses that gap by examining AKI risks in patients severely ill with either Covid-19 or influenza A, highlighting broader implications for intensive care management.

The research team conducted a retrospective study using electronic health records from the Hospital Authority, encompassing 4,328 ICU patients across 15 public hospitals in Hong Kong from January 2013 to April 2023. Of these, 2,787 tested positive for SARS-CoV-2, while 1,541 tested positive for influenza A.

Results indicated that 37.8pc of Covid-19 patients developed AKI during their ICU stay, compared to 53.7pc of influenza A patients. After adjusting for various factors, the risk of AKI in influenza A patients was found to be double that of Covid-19 patients. The incidence of severe and prolonged AKI was also significantly higher among those with influenza A.

The study suggests several factors contributing to the increased AKI risk in influenza A patients. One possibility is that the influenza virus may be more damaging to the kidneys than the Covid-19 virus.

Additionally, higher Covid-19 vaccination rates might have offered some protection against kidney damage, with over 70pc of adults aged 20 to 59 and over 60pc of adults aged 60 to 69 being vaccinated, compared to significantly lower influenza vaccination rates.

Dr. Yap Yat-hin emphasized the importance of ongoing vigilance and preventive measures for severe respiratory viral infections. “Despite the lower risk of kidney complications in Covid-19 patients, the higher incidence of AKI associated with influenza underscores the need for robust vaccination strategies for at-risk populations,” he said.

The study was led by Dr. Desmond Yap Yat-hin from the Division of Nephrology, Department of Medicine, School of Clinical Medicine, HKUMed, and included contributions from April Ip See-wai, Dr. Simon Sin Wai-ching, Dr. Pauline Yeung Pui-ning from the Critical Care Medicine Unit, Dr. Andrew Ng Kei-yan from the Department of Medicine, and Dr. Jasper Chan Fuk-woo and Prof Kelvin To Kai-wang from the Department of Microbiology.