Long-term kidney outcomes after COVID-19: a matched cohort study using the OpenSAFELY platform

Background: COVID-19 severe enough to require hospitalisation is commonly associated with acute kidney injury. However, it remains unclear whether COVID-19 leads to long-term kidney outcomes in the broader population. Methods: We undertook a population-based, matched cohort study. With the approval of NHS England, we used primary and secondary care electronic health records from England using the OpenSAFELY-TPP platform. We compared people with and without COVID-19 using fully-adjusted, stratified, cause-specific Cox models for kidney failure, 50% reduction in kidney function, and death. Findings: Overall, all outcomes were increased after COVID-19 over the course of follow-up (HR for kidney failure 1.93 [95% CI 1.84–2.03]). Hazards of kidney failure were greatest after hospitalisation (HR 7.74 [95% CI 7.00–8.56]) and remained increased beyond 180 days of follow-up. There was no evidence of increased risk in those not hospitalised (HR 0.85 [95% CI 0.79–0.90]). Increased kidney failure was more pronounced in black ethnicity (HR 4.50 [95% CI 2.92–6.92]) compared to white ethnicity (HR 1.82 [95% CI 1.71–1.94]). Amongst those hospitalised with COVID-19, there was no attenuation of kidney failure between the first wave (HR 8.74 [95% CI 6.88–11.08]) and the Omicron wave (HR 8.36 [95% CI 6.81–10.27]). Interpretation: We observed increased long-term kidney outcomes in people hospitalised with COVID-19, as well as notable ethnic differences. Our results suggest strategies to minimise severe COVID-19 should continue to be optimised among vulnerable groups, and that kidney function should be proactively monitored after hospital discharge. Funding: National Institute for Health and Care Research.