Patients who were critically ill with COVID-19 were found to have a 49% lower risk of developing acute kidney injury compared to those infected with influenza A, according to a large-scale study.

The retrospective cohort study evaluated the risk of acute kidney injury (AKI) in critically ill patients with COVID-19 compared to those with seasonal influenza who were admitted to intensive care units across 15 public hospitals in Hong Kong between January 2013 and April 2023. The study, published in eClinical Medicine, included 4,328 patients: 2,787 infected with COVID-19 and 1,541 infected with influenza A. Exclusion criteria included patients on chronic dialysis and those with missing confounder data.

After adjusting for confounders such as age, sex, baseline estimated glomerular filtration rate, comorbidities, and severity of illness, patients with COVID-19 demonstrated a significantly lower risk of developing AKI compared with those with influenza A. The adjusted odds ratio (aOR) for AKI in patients with COVID-19 was 0.51 (95% confidence interval [CI] = 0.42-0.61; P < .0001), representing a 49% lower risk. Overall, 37.8% of patients with COVID-19 (1,053 of 2,787) developed AKI compared to 53.7% of those with influenza A (828 of 1,541).

Stage 3 AKI occurred in 15.5% of patients with COVID-19 (432 of 2,787) compared to 24.3% of those with influenza A (375 of 1,541). The aOR for developing stage 3 AKI was 0.57 (95% CI = 0.45-0.72; P < .0001). Acute kidney disease (AKD) was observed in 66.2% of COVID-19 patients (1,844 of 2,787), while 76.4% of influenza A patients (1,177 of 1,541) developed AKD. The aOR for AKD was 0.66 (95% CI = 0.53-0.82; P = .0002).

Renal replacement therapy (RRT) was needed for 11.3% of COVID-19 patients (316 of 2,787) compared to 20.8% of patients with influenza A (320 of 1,541). The aOR for requiring RRT was 0.52 (95% CI = 0.40-0.67; P < .0001).

The hospital mortality rate was 20.2% for COVID-19 patients (562 of 2,787) compared to 22.7% for influenza A patients (349 of 1,541). The aOR for hospital mortality was 1.29 (95% CI = 1.01-1.65; P = .038), though this association lost significance after adjusting for propensity scores.

The lower risk of AKI observed in patients with COVID-19 infection may reflect changes in treatment and management strategies over the course of the pandemic, but further research is needed to explore these factors. 

The authors declared no competing interests.