TABLE 1

Predictive statistics for the ability of a single baseline induced sputum measurement of neutrophil elastase (NE) (activity or total protein as indicated) to predict a NE measurement above the predefined threshold at follow-up or at any stage during the study

Outcome and testSensitivity %Specificity %PPV %NPV %
“High” NE at day 14
 FRET active NE100100100100
 Active NE (ProteaseTag)1007550100
 Total NE ELISA10085.775100
“High” NE at any time-point
 FRET active NE66.710010066.7
 Active NE (ProteaseTag)8010010083.3
 Total NE ELISA66.710010066.7
Above lower 95% CI at day 14
 FRET active NE10085.775100
 Active NE (ProteaseTag)1007550100
 Total NE ELISA10085.775100
Above lower 95% CI at any time-point
 FRET active NE8010010083.3
 Active NE (ProteaseTag)8010010083.3
 Total NE ELISA60807566.7
Above upper 95% CI at day 14
 FRET active NE100100100100
 Active NE (ProteaseTag)10088.950100
 Total NE ELISA100100100100
Above upper 95% CI at any time-point
 FRET active NE66.710010087.5
 Active NE (ProteaseTag)100100100100
 Total NE ELISA10087.566.7100

PPV: positive predictive value; NPV: negative predictive value; FRET: fluorescence resonance energy transfer.