Authors: Lei S-H et al.
Anesthesiology, November 2025. DOI: 10.1097/ALN.0000000000005859
Summary
This large observational cohort study examined whether discrepancies between cystatin C–based and creatinine-based estimated glomerular filtration rate (eGFR) are associated with adverse postoperative outcomes in patients undergoing major noncardiac surgery. The investigators analyzed two geographically distinct Chinese hospital cohorts: 35,488 patients from the Nanfang cohort and 23,417 from the Xinjiang cohort.
The exposure of interest was eGFRdiff, defined as cystatin C eGFR minus creatinine eGFR. A more negative eGFRdiff reflects lower kidney function estimated by cystatin C than by creatinine—potentially revealing occult kidney dysfunction not detectable by creatinine alone. The primary outcome was a composite of postoperative complications and death.
The composite outcome occurred in 8.4% of the Nanfang cohort and 14.4% of the Xinjiang cohort. In both cohorts, progressively more negative eGFRdiff values were independently associated with higher postoperative risk. For every 10 mL/min/1.73 m² decrease in eGFRdiff, adjusted odds of the primary outcome increased by 12% in Nanfang and 11% in Xinjiang. These associations persisted across multiple complication categories, including cardiovascular events, acute kidney injury, infections, pulmonary complications, and mortality. The consistent findings across two distinct populations strengthen the external validity.
The study suggests that discordance between cystatin C and creatinine may serve as a novel marker of increased perioperative risk, identifying patients whose renal function is worse than creatinine would indicate.
Key Points
• Large two-cohort study evaluating eGFR discordance and surgical risk.
• A more negative cystatin C–minus–creatinine eGFR difference strongly predicted postoperative complications and death.
• Associations were consistent across geographically and ethnically distinct populations.
• eGFRdiff may provide a valuable perioperative risk-stratification tool.
• Findings highlight limitations of creatinine-only renal assessment.
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