Prediction of Acute Glomerular Filtration Rate Reductions Following Renin-angiotensin System Blockade in Chronic Kidney Disease: A Possible Application of Ultrasonography in Clinical Practice

Figures

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  Figure 1.. Doppler ultrasonography and a schematic illustration of the RI. The resistive index (RI) is calculated as follows: (peak-systolic velocity - end-diastolic velocity)/peak-systolic velocity. PSV: peak-systolic velocity, EDV: end-diastolic velocity

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  Figure 2.. Cumulative probabilities of acute GFR reductions following RAS blockade. A Kaplan-Meier analysis according to the initial resistive index (RI). The bold line denotes RI >0.70, and the fine line denotes RI≤0.70. The cumulative probability of acute GFR reductions at 14 weeks was 3.3% and 53% in patients with RI≤0.70 and RI>0.70, respectively. Log-rank test, p<0.001. An acute GFR reduction was defined as a decrease in GFR of ≥30%.

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  Figure 3.. Cumulative probabilities of acute GFR reductions following RAS blockade stratified by DKD. A Kaplan-Meier analysis according to the initial resistive index (RI) stratified by diabetic kidney disease (DKD). The bold line denotes RI>0.70 and the fine line denotes RI≤0.70. (A) DKD. The cumulative probability of acute GFR reductions at 14 weeks was 9.1% and 53% in patients with RI ≤0.70 and RI>0.70, respectively. Log-rank test, p<0.05. (B) non-DKD. The cumulative probability of acute GFR reductions at 14 weeks was 1.9% and 46% in patients with RI≤0.70 and RI>0.70, respectively. Log-rank test, p<0.001. An acute GFR reduction was defined as a decrease in GFR of ≥30%.

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  Figure 4.. Univariate hazard ratios for acute GFR reductions. A Cox proportional-hazards analysis was used to calculate the hazard ratio as estimates of relative risks of acute GFR reductions, defined as in the legend to Fig. 2. The figure shows hazard ratios with 95% confidence intervals. The variables investigated were RI×100 (i.e., an increase in RI of 0.01), age, eGFR, systolic blood pressure, urinary protein excretion ×10 (i.e., an increase in urinary protein of 0.1 g/g creatinine), diabetic kidney disease, coronary artery disease, and use of diuretics. All of these variables proved to be significant risk factors for acute GFR reductions. HR: hazard ratio, CI: confidence interval, RI: resistive index, eGFR: estimated glomerular filtration rate, BP: blood pressure, U-protein: urinary protein, Cr: creatinine, DKD: diabetic kidney disease, CAD: coronary artery disease

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  Figure 5.. Univariate and multivariate odds ratios of achieved diastolic blood pressure for acute GFR reductions. A logistic regression analysis was used to calculate the odds ratio for acute GFR reductions, defined as in the legend to Fig. 2. The figure shows odds ratios with 95% confidence intervals. The variables investigated were RI×100 (i.e., an increase in RI of 0.01) and achieved diastolic blood pressure (i.e., diastolic pressure at the end of follow-up). The achieved diastolic pressure had no effect on acute GFR reductions. OR: odds ratio, CI: confidence interval, RI: resistive index, DBP: diastolic blood pressure

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  Figure 6.. Receiver operating characteristic (ROC) curve for the RI. The highest sensitivity and specificity were attained at RI of 0.70, where the sensitivity was 91% (21/23, number/total number) and the specificity was 69% (59/85, number/total number), showing that 0.70 was suitable as the cutoff value. The area under the curve (AUC) was 0.85, showing moderate accuracy for predicting acute GFR reductions.