Table 2.
Performance Characteristics of HR-ARM Findings vs Abnormal BET in Constipated Patients (n=474)
| Anorectal variable | Abnormal BET results, No. (%) | Sensitivity, % | Specificity, % | Positive predictive value, % | Negative predictive value, % | AUROC, % |
|---|---|---|---|---|---|---|
| High anal resting pressure | 18/34 (53) | 12 | 95 | 53 | 70 | 53 |
| Reduced anal squeeze increment | 43/108 (40) | 28 | 80 | 40 | 70 | 54 |
| Evacuation | ||||||
| Reduced rectal pressure increase | 16/37 (43) | 11 | 94 | 43 | 69 | 52 |
| High residual anal pressure | 26/54 (48) | 17 | 91 | 48 | 70 | 54 |
| Reduced anal relaxation | 31/71 (44) | 20 | 88 | 44 | 70 | 54 |
| Reduced rectoanal gradient | 54/101 (53) | 36 | 85 | 53 | 74 | 60 |
| Increased rectal sensory threshold for urgency | 20/39 (51) | 13 | 94 | 51 | 69 | 54 |
| Number of abnormal variables threshold | 65a | |||||
| 1 | 52/155 (34) | 72 | 50 | 41 | 79 | |
| 2 | 27/64 (42) | 37 | 83 | 51 | 73 | |
| 3 | 17/32 (53) | 19 | 95 | 64 | 71 | |
| 4 | 9/9 (100) | 7 | 99.7 | 92 | 69 | |
| 5 | 1/1 (100) | 1 | 100.0 | 100 | 68 | |
| 6 | 1/1 (100) | 1 | 100.0 | 100 | 68 |
Abbreviations: AUROC, area under the receiver operating curve; BET, balloon expulsion time; HR-ARM, high-resolution anal manometry; N/A, not applicable.
a
The AUROC was calculated for a model that included a threshold of 1 or more abnormal variables. Fifteen patients with missing data for sensation were excluded from the sensitivity and specificity analysis for the total number of abnormal variables.