# Table 2 The sensitivity, specificity, and positive and negative predictive values of Q1 and Q2 using different PEI cut-off scores, n = 466

PEI cut-off score Sensitivity (%) Specificity (%) Positive predictive value (PPV), (%) Negative predictive value (NPV), (%)
Q1 Q2 Q1 Q2 Q1 Q2 Q1 Q2
Zero points
(0 vs 1–12)
86.6 64.8 75.4 100.0 86.9 54.4 41.4 100.0
Three points
(0–3 vs 4–12)
69.7 92.0 66.9 81.4 70.0 78.4 68.6 93.3
Six points
(0–6 vs 7–12)
90.0 98.1 60.0 63.9 38.4 43.2 95.6 98.1
1. Sensitivity = the proportion of “true positive” patients, i.e. patients who answered positively to Q1 or Q2 among those who had higher PEI scores
2. Specificity = the proportion of “true negative” patients, i.e. patients who answered negatively to Q1 or Q2 among those who had lower PEI scores
3. Positive predictive value = the proportion of patients who actually had a higher PEI score among those who answered positively to Q1 or Q2
4. Negative predictive value = the proportion of patients who actually had a lower PEI score among those who answered negatively to Q1 or Q2