Table 2.
Evaluation parameters in three different strategies
| Negative number n (%) | Number needed to test | False negatives number (%) | Positive predictive value (%, 95% CI) | Negative predictive value (%, 95% CI) | Sensitivity (%, 95% CI) | Specificity (%, 95% CI) | |
|---|---|---|---|---|---|---|---|
| 0.5 | 594 (22) | 4.2 | 42 (15) | 11 (9.7, 12.4) | 93 (90.5, 94.8) | 85 (80.1, 88.9) | 22 (20.7, 24.0) |
| 0.01*age | 979 (35) | 2.5 | 64 (23) | 12 (10.7, 13.8) | 94 (91.7, 94.9) | 77 (71.7, 81.8) | 37 (35.0, 38.8) |
| 0.02*age | 1293 (59) | 1.5 | 115 (41) | 15 (12.7, 16.9) | 93 (91.6, 94.1) | 59 (52.9, 64.7) | 61 (59.3, 63.2) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 148 (30) | 3 | 8 (15) | 14 (10.2, 17.7) | 95 (89.3, 97.5) | 86 (72.8, 93.1) | 32 (27.5, 36.4) |
| 0.01*age | 183 (37) | 2.4 | 10 (18) | 14 (10.8, 18.9) | 95 (89.9, 97.2) | 82 (68.6, 90.5) | 39 (34.8, 44.1) |
| 0.02*age | 291 (59) | 1.5 | 26 (42) | 14 (9.9, 19.9) | 91 (87.0, 94.0) | 53 (38.9, 66.1) | 60 (55.5, 64.8) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 166 (32) | 2.8 | 17 (38) | 8 (5.4, 11.4) | 90 (83.9, 93.7) | 62 (46.5, 75.8) | 32 (27.4, 35.9) |
| 0.01*age | 221 (43) | 2.1 | 19 (42) | 9 (5.9, 12.7) | 91 (86.7, 94.6) | 58 (42.2, 72.0) | 43 (38.2, 47.3) |
| 0.02*age | 335 (65) | 1.4 | 26 (58) | 10 (6.5, 16.0) | 92 (88.7, 94.8) | 42 (28.0, 57.8) | 65 (60.8, 69.6) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 121 (22) | 4 | 13 (19) | 13 (10.2, 16.8) | 89 (82.0, 93.9) | 81 (70.0, 89.4) | 22 (18.7, 26.3) |
| 0.01*age | 208 (37) | 2.3 | 22 (31) | 13 (10.5, 18.0) | 89 (84.2, 93.1) | 69 (56.2, 78.9) | 38 (34.0, 42.9) |
| 0.02*age | 340 (61) | 1.4 | 36 (51) | 16 (11.3, 21.5) | 89 (85.5, 92.4) | 49 (36.6, 60.7) | 63 (58.2, 67.0) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 97 (16) | 5.7 | 2 (4) | 10 (7.4, 12.5) | 94 (82.8, 98.5) | 95 (84.5, 98.) | 9 (6.5, 11.4) |
| 0.01*age | 189 (31) | 2.9 | 7 (12) | 11 (8.1, 14.8) | 93 (89.2, 96.0) | 72 (58.3, 82.6) | 40 (36.3, 44.7) |
| 0.02*age | 332 (54) | 1.7 | 14 (24.56) | 15 (11.5, 20.3) | 96 (92.9, 97.6) | 75 (62.0, 85.5) | 57 (53.2, 61.5) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 44 (11) | 8.4 | 2 (5.26) | 10 (7.1, 13.6) | 96 (83.3, 99.2) | 95 (80.9, 99.1) | 11 (8.4, 15.2) |
| 0.01*age | 120 (29) | 3.1 | 6 (15.79) | 11 (7.9, 15.5) | 95 (89.0, 98.0) | 84 (68.1, 93.4) | 31 (26.3, 35.9) |
| 0.02*age | 240 (59) | 1.5 | 13 (34.21) | 15 (10.1, 21.5) | 95 (90.7, 97.0) | 66 (48.6, 79.9) | 62 (56.3, 66.5) |
| P | – | – | – | – | – | < 0.05 | < 0.05 |
| 0.5 | 18 (10) | 8.8 | 0 (0.00) | 10 (5.7, 15.7) | 100 (78.1, 100.0) | 100 (74.7, 100.0) | 11 (7.1, 17.7) |
| 0.01*age | 58 (34) | 2.7 | (0.00) | 13 (7.7, 20.9) | 100 (92.3, 100.0) | 100 (74.7, 100.0) | 37 (29.3, 44.8) |
| 0.02*age | 96 (55) | 1.6 | 0 (0.00) | 20 (11.7, 30.4) | 100 (95.2, 100.0) | 100 (74.7, 100.0) | 61 (52.7, 68.3) |
| P | – | – | – | – | – | > 0.05 | < 0.05 |
Number needed to test to find one normal D-dimer test result