Table 4.
Predictive characteristics of Bishop score versus simplified Bishop score.
| Score | Sensitivity % | Specificity % | PPV % | NPV % | LR + | Correct classification rate % |
|---|---|---|---|---|---|---|
| Original Bishop | ||||||
| > 5 | 75.1 | 49.2 | 81.8 | 39.3 | 1.47 | 68.7 |
| > 6 | 62.9 | 62.8 | 83.8 | 35.7 | 1.69 | 62.9 |
| > 7 | 49.8 | 75.8 | 86.2 | 33.1 | 2.05 | 56.2 |
| > 8 | 35.3 | 83.8 | 87.0 | 29.8 | 2.19 | 47.3 |
| Simplified Bishop | ||||||
| > 3 | 75.8 | 49.3 | 82.0 | 40.1 | 1.49 | 69.4 |
| > 4 | 59.2 | 67.9 | 84.9 | 35.3 | 1.84 | 61.4 |
| > 5 | 40.6 | 82.6 | 87.7 | 31.3 | 2.34 | 51.0 |
| > 6 | 18.8 | 94.2 | 90.8 | 27.6 | 3.25 | 37.4 |
PPV, positive predictive value; NPV, negative predictive value; LR+, likelihood ratio positive (calculated by sensitivity/(1 – specificity)); the correct classification rate was calculated by number of true positives + number of true negatives/number of subjects classified.
Original Bishop includes dilation, effacement, station, consistency and position with a possible range from 0 – 13; Simplified Bishop includes dilation, station and effacement only with a possible range from 0 – 9.