Reduced kidney function, urine output tied to kidney nonrecovery in COVID-19 patients

Among critically ill patients with COVID-19, those who present with lower baseline estimated glomerular filtration rate (eGFR) and reduced urine output at the time of kidney replacement therapy (KRT) initiation are more likely to experience kidney nonrecovery, according to a study.

The analysis included 4,221 patients (mean age 61 years, 63 percent male, 26 percent had eGFR <60 mL/min/1.73m²) with COVID-19 who were admitted to an intensive care unit (ICU) and not receiving KRT at baseline (ICU cohort). A total of 2,361 (56 percent) developed AKI after ICU admission, among whom 876 were subsequently treated with KRT (AKI-KRT subcohort).

More severe AKI (defined by its peak severity within the first 14 days of ICU admission) was associated with greater mortality risk, as well as with a higher likelihood of kidney nonrecovery and lower kidney function at discharge among survivors.

In the AKI-KRT subcohort, 588 patients (67 percent) died, 95 (11 percent) had kidney nonrecovery, and 193 (22 percent) experienced kidney recovery by the time of discharge.

Multinomial logistic regression showed that the odds of kidney nonrecovery was greater among patients with lower baseline eGFR (chronic kidney disease [CKD] GFR category 3: odds ratio [OR], 2.09, 95 percent confidence interval [CI], 1.09–4.04; CKD GFR category 4: OR, 4.27, 95 percent CI, 1.99–9.17; CKD GFR category 5: OR, 8.69, 95 percent CI, 3.07–24.55) relative to eGFR >60 mL/min/1.73 m².

Compared with normal urine output (≥500 mL urine/day), oliguria at the time of KRT initiation was associated with a higher likelihood of kidney nonrecovery (50–499 mL urine/day: OR, 2.10, 95 percent CI, 1.14–3.88; <50 mL urine/day: OR, 4.02, 95 percent CI, 1.72–9.39).

The study was limited by the failure to capture later recovery events due to lack of follow-up data following discharge.