A cohort study of 134,565 COVID-19 patients and 35,987 pneumonia patients in Stockholm found that COVID-19 infection was associated with an accelerated decline in kidney function when compared to pneumonia.
The study, conducted from February 2018 to January 2022, reported a 3.4% annual decline in estimated glomerular filtration rate (eGFR) for COVID-19 patients versus 2.3% for pneumonia patients after adjusting for covariates. Among hospitalized cases, COVID-19 patients experienced a sharper decline of 5.4% annually compared to pneumonia patients, where hospitalization had no additional impact on eGFR loss.
Over a median follow-up of 10.8 months, a 25% reduction in eGFR occurred in 0.8% of COVID-19 survivors versus 1.7% of pneumonia survivors. The adjusted hazard ratio for a 25% reduction was 1.19 for COVID-19 versus pneumonia, rising to 1.42 among hospitalized patients. Preinfection eGFR slopes were stable for COVID-19 patients but showed slight declines for pneumonia patients, according to results published in JAMA Network Open.
Hospitalized COVID-19 patients had a higher incidence of acute kidney injury (19%) than hospitalized pneumonia patients (22.7%). The median age of the COVID-19 cohort was 51 years, with a baseline median eGFR of 94 mL/min/1.73m². In contrast, pneumonia patients were older (median age 71) and had a lower baseline median eGFR of 79 mL/min/1.73m².
Approximately half of both cohorts underwent creatinine testing before infection, but many lacked postinfection testing, limiting generalizability. Sensitivity analyses excluding individuals without postinfection measurements or those with a history of pneumonia confirmed the findings.
The study's limitations included a lack of ethnicity and body mass index data and short follow-up duration. However, its design excluded eGFR measurements during acute illness to better capture chronic kidney function trends.
Researchers recommend closer monitoring of kidney function in hospitalized COVID-19 patients to enable early detection and management of chronic kidney disease.
Conflict of interest disclosures can be found in the study.