Measurement of the intrarenal arterial resistance index for the identification and prediction of diabetic nephropathy.
OBJECTIVE
High intrarenal resistance index (RI) predicts renal function in several conditions; its use in the prediction of diabetic nephropathy (DN) is little explored. We aimed (1) to compare RI in diabetic and non diabetic hypertensive patients, and (2) to evaluate whether high RI is associated with clinical signs of DN and its progression over time.


RESULTS



METHODS
observational, prospective.


METHODS
92 type 2 diabetic patients and 37 non-diabetic controls aged 40-70, with hypertension and normal renal function. We measured ultrasound RI and, among others, creatinine, estimated glomerular filtration rate and urinary albumin excretion rate (AER) at baseline and after 4.5 years follow-up. Progression of albuminuric state (i.e., transition from baseline normo-microalbuminuria to follow-up micro-macroalbuminuria) was evaluated. RI was significantly higher in diabetic than non-diabetic participants (0.69+/-0.05 vs 0.59+/-0.05, p<0.001). Diabetic patients with RI>or=0.73, i.e., above the 80th percentile of the RI distribution, had significantly higher baseline AER and a more frequent progression of the albuminuric state compared to patients with RI<0.73 (27.7microg/mg [12.1-235.4] vs 15.1microg/mg [8.6-33.4]; 52.9% vs 9.5%, respectively). AER increased significantly from baseline to follow-up in patients with RI>or=0.73 (from 27.7microg/mg [12.1-235.4] to 265.0microg/mg [23.8-1018.1], p<0.01), but not in those with RI<0.73 (from 15.1microg/mg [8.6-33.4] to 16.1microg/mg [10.7-67.2], ns). OR for progression of albuminuric state, adjusted for established predictors of DN, including baseline AER, was 5.01 (1.4-17.7, 95% CI) for patients with RI>or=0.73 vs <0.73. Findings were confirmed in patients with normoalbuminuria at baseline.


CONCLUSIONS
In diabetic patients, high RI (>or=0.73) is associated with features of DN and its progression over time, independent of albuminuria.
Masulli
M
M
Department of Clinical and Experimental Medicine, Federico II University, Naples, Italy. magia77@inwind.it
Mancini
M
M
Liuzzi
R
R
Daniele
S
S
Mainenti
P P
PP
Vergara
E
E
Genovese
S
S
Salvatore
M
M
Vaccaro
O
O
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000453:epidemiology*; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000453:epidemiology; D003928:Diabetic Nephropathies / Q000453:epidemiology* / Q000209:etiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000453:epidemiology; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014463:Ultrasonography; D014655:Vascular Resistance