Pre-lung transplant measures of reflux on impedance are superior to pH testing alone in predicting early allograft injury

Table 3 Area under the receiver operating characteristic curve or c-statistic comparing prediction value of pH-testing and corresponding impedance measures of reflux for early allograft injury

	Area under ROC/Harrell’s c-stat
pH parameter of reflux
Acid reflux exposure, upright	0.58
Acid reflux exposure, recumbent	0.69
Acid reflux exposure, overall	0.61
Elevated acid reflux exposure (> 4.2%)	0.39
Total acid reflux episodes	0.60
Acid clearance	0.64
Impedance parameter of reflux
Total reflux exposure, upright	0.63
Total reflux exposure, recumbent	0.74
Total reflux exposure, overall	0.67
Elevated total reflux exposure (> 1.4%)	0.77
Total reflux episodes	0.64
Bolus clearance	0.74

Note that all values deriving from impedance measures are greater than those from pH measures, suggesting that impedance data are better predictors.