Association of Statin Use with Renal Resistive Index Across CKD Stages: ACross-Sectional Study

Introduction: This study examined the association between statin exposure and the RRI in adults evaluated for CKD. We aimed to determine whether continuous statin use is linked to lower RRI, reflecting better renal vascular resistance and microvascular health. Methods: Participants were adults ≥18 years undergoing CKD evaluation. CKD staging followed KDIGO guidelines, with eGFR estimated by the Cockcroft–Gault equation. RRI was measured by echo-color Doppler ultrasound (Affiniti 70, Philips). For each kidney, three Doppler waveforms were obtained from the upper, middle, and lower poles, and the mean bilateral RRI was calculated as (PSV − EDV)/PSV, where PSV is peak systolic velocity and EDV is end-diastolic velocity. Statin exposure was defined as active daily atorvastatin ≥20 mg for ≥12 months, confirmed by self-report and medication review. Results: Among 130 participants, 60 (46.2%) reported statin use. In the adjusted model, statin use was independently associated with a lower RRI (B = −0.038; 95% CI −0.054 to −0.022; p <0.001), corresponding to about a 0.04-unit reduction in mean RRI versus non-use. Higher CKD stage and elevated LDL were associated with higher RRI. Subgroup analyses showed more pronounced reductions among older adults (>60 years), males, individuals with BMI ≥30, and across CKD stages 2–5 and GFR ≤43 mL/min/1.73 m² Discussion: Prospective studies and randomized trials are needed to determine if statins causally improve intrarenal hemodynamics and to elucidate underlying mechanisms. Conclusion: There is an association between statin use and lower RRI, but causality is not established due to the cross-sectional design.