Background
The significance of chronic kidney disease on susceptibility to COVID-19 and subsequent outcomes remains unaddressed.

Objective
To investigate the association of estimated glomerular filtration rate (eGFR) on risk of contracting COVID-19 and subsequent adverse outcomes.

Methods
Rates of hospital-diagnosed COVID-19 were compared across strata of eGFR based on conditional logistic regression using a nested case–control framework with 1:4 matching of patients diagnosed with COVID-19 with controls from the Danish general population on age, gender, diabetes and hypertension. Risk of subsequent severe COVID-19 or death was assessed in a cohort study with comparisons across strata of eGFR based on adjusted Cox regression models with G-computation of results to determine 60-day risk standardized to the distribution of risk factors in the sample.

Results
Estimated glomerular filtration rate was inversely associated with rate of hospital-diagnosed COVID-19: eGFR 61–90 mL/min/1.73m2 HR 1.13 (95% CI 1.03–1.25), P = 0.011; eGFR 46–60 mL/min/1.73m2 HR 1.26 (95% CI 1.06–1.50), P = 0.008; eGFR 31–45 mL/min/1.73m2 HR 1.68 (95% CI 1.34–2.11), P < 0.001; and eGFR ≤ 30 mL/min/1.73m2 3.33 (95% CI 2.50–4.42), P < 0.001 (eGFR > 90 mL/min/1.73m2 as reference), and renal impairment was associated with progressive increase in standardized 60-day risk of death or severe COVID-19; eGFR > 90 mL/min/1.73m2 13.9% (95% CI 9.7–15.0); eGFR 90–61 mL/min/1.73m2 16.1% (95% CI 14.5–17.7); eGFR 46–60 mL/min/1.73m2 17.8% (95% CI 14.7–21.2); eGFR 31–45 mL/min/1.73m2 22.6% (95% CI 18.2–26.2); and eGFR ≤ 30 mL/min/1.73m2 23.6% (95% CI 18.1–29.1).

Conclusions
Renal insufficiency was associated with progressive increase in both rate of hospital-diagnosed COVID-19 and subsequent risk of adverse outcomes. Results underscore a possible vulnerability associated with impaired renal function in relation to COVID-19.