highly significantP = .004
Urine sodium of 130 mmol/L or greater was the most highly significant predictor of nonresponse to FR (OR 15.0; 95% CI, 2.4-95.8; P = .004) and while the closely-related Fürst ratio greater than 1 also predicted nonresponse, it performed less well (OR 2.7; 95% CI, 1.0-7.6; P = .05).