A 5-item prediction rule to identify severe renal dysfunction in patients with acute stroke

Background and Purpose — Although patients with severe renal dysfunction who receive iodinated contrast are at high risk of CIN, contrast-enhanced CT scans are often obtained without prior knowledge of kidney function in patients with acute stroke. The researchers aimed to develop a tool to identify patients with acute stroke at a high risk of CIN in the absence of a recent GFR.

Materials and Methods — The researchers used the Registry of the Canadian Stroke Network (9872 patients) and Ontario Stroke Audit (2544 patients) for the derivation and validation cohort, respectively. A multivariable logistic regression model was performed to develop a predictive tool to identify severe renal dysfunction (defined as a GFR < 30 mL/min/1.73 m2).

Results — The overall prevalence of severe renal dysfunction was 4.9% and 5.2% in the derivation and validation cohort, respectively. The prediction rule was designed as follows: (age in years) = (5 points for women) = (5 points for history of diabetes mellitus) = (15 points for preadmission insulin use) = (10 points for history of hypertension). The prevalence of severe renal dysfunction is negligible in patients with a total score of ≤70 (≤0.005%–0.7%) but increases with higher Renal Risk Scores (e.g., scores 71–80: 2.1%–2.2%; scores 91–100: 6.6%–7.1%; scores 111–120: 15.9%–28.1%).

Conclusions — The Renal Risk Score is a validated tool that helps clinicians select which patients with stroke can safely proceed to contrast-enhanced brain imaging without waiting for laboratory evidence of good renal function.