Screening performance of the test tree
| Characteristics | Test tree nodes | Sensitivity | Specificity | Positive predictive value | Negative predictive value |
| Under 45 | Red node (9) | 0.66 (55/83) | 0.99 (610/615) | 0.92 (55/60) | 0.96 (610/638) |
| 45 years+ | Red nodes (3, 15) | 0.64 (212/332) | 0.77 (204/264) | 0.78 (212/272) | 0.63 (204/324) |
| All ages | Red nodes (3, 9, 15) | 0.64 (267/415) | 0.93 (814/879) | 0.80 (267/332) | 0.85 (814/962) |
Data are percentages, with numbers of non-indigents and/or indigents in parentheses.
Negative predictive value in under 45 was 96% (red and orange nodes)=((total non-indigents in node 2)–(total non-indigents in nodes 5 and 11))/((total indigents in node 2–total indigents in nodes 5 and 11)+(total non-indigents in node 2–total non-indigents in nodes 5 and 11))x 100.
Sensitivity in under 45 was 66% (red node)=(total indigents in node 9)/(total indigents in this age group; node 2)x100.
Specificity in all ages was 93% (red nodes)=((total non-indigents in node 1)–(total non-indigents in nodes 3)]+((total non-indigents in node 2)–(total non-indigents in nodes 5))/total non-indigents in all ages groups (nodes 1 and 2)x100.
Positive predictive value in all ages was 80% (red nodes 3, 9 and 15)=(total indigents in red nodes 3, 9 and 15)/(total non-indigent and indigents in red nodes 3, 9 and 15)x100.