Baseline characteristics of the 1010 study patients
| Characteristic . | Negative D-dimer (N = 528) . | Positive D-dimer (N = 482) . | P value . | Positive D-dimer without anticoagulation (N = 109) . | Positive D-dimer with anticoagulation (N = 373) . | P value . |
|---|---|---|---|---|---|---|
| Male sex, n (%) | 277 (52.5) | 283 (58.7) | .055 | 70 (64.2) | 213 (57.1) | .230 |
| Age (y), median (IQ) | 63 (45-75) | 69 (58-79) | <.0001 | 64 (49-72) | 71 (61-80) | <.0001 |
| Age >70 y, n (%) | 201 (38.1) | 223 (46.3) | .011 | 32 (29.3) | 191 (51.2) | <.0001 |
| Type of VTE, n (%) | ||||||
| Proximal DVT with no PE | 285 (54.5) | 244 (51.4) | .384 | 53 (49.1) | 191 (52.0) | .677 |
| DVT plus symptomatic PE | 97 (18.5) | 113 (23.8) | .037 | 26 (24.1) | 87 (23.7) | .968 |
| Isolated PE | 141 (27.0) (5 NA) | 118 (24.8) (7 NA) | .379 | 29 (26.8) (1 NA) | 89 (24.3) (6 NA) | .689 |
| Type of risk factors, n (%) | ||||||
| Idiopathic | 377 (71.4) | 394 (81.7) | <.0001 | 83 (76.1) | 311 (83.4) | |
| WRFs | 151 (28.6) | 88 (18.3) | <.0001 | 26 (23.9) | 62 (16.6) | .115 |
| Minor general, laparoscopic, or arthroscopic surgery | 7 | 2 | 1 | 1 | .115 | |
| Pregnancy or puerperium | 3 | 1 | 1 | 0 | ||
| Hormonal contraceptive replacement therapy | 90 | 30 | 11 | 19 | ||
| 8 | 2 | 1 | 1 | |||
| Long travel | 5 | 8 | 3 | 5 | ||
| Minor trauma, leg injury, reduced mobility | 17 | 20 | 8 | 13 | ||
| Hospitalization in a medical ward | 21 | 27 | 1 | 23 | ||
| Duration of previous anticoagulation, n (%) | ||||||
| ≤6 mo | 160 (30.3) | 141 (29.3) | .784 | 29 (26.6) | 112 (30.0) | .574 |
| 7-12 mo | 297 (56.2) | 272 (56.4) | 1.000 | 61 (56.0) | 211 (56.6) | .999 |
| >12 mo | 71 (13.5) | 69 (14.3) | .786 | 19 (17.4) | 50 (13.4) | .375 |
| Total duration of FU for all patients, y | 829 | 772 | 171 | 601 | ||
| FU, y, median (IQ) | 1.93 (1.25-2.00) | 1.90 (1.29-2.00) | .508 | 1.97 (1.23-2.00) | 1.88 (1.29-2.00) | .990 |
| Duration of FU, n | ||||||
| 2 y | 266 | 239 | 59 | 180 | ||
| 1-2 y | 169 | 165 | 29 | 136 | ||
| <1 y | 57* | 49 | 7 | 42 | ||
| Patients censored during FU, n (%) | 36 (6.8) | 29 (6.0) | .697 | 14 (12.8) | 15 (4.0) | .002 |
| Lost to FU, n (%) | 6 (1.1) | 1 (0.2) | .179 | 1 (0.9) | 0 | .535 |
| Presence of RVT (>4 mm), n (%) | 56 (10.6) | 63 (13.1) | .263 | 5 (4.6) | 58 (15.5) | .005 |
| Associated antiplatelet treatment, n (%) | 53 (10.0) | 42 (8.7) | .553 | 10 (9.2) | 32 (8.6) | .999 |
| Characteristic . | Negative D-dimer (N = 528) . | Positive D-dimer (N = 482) . | P value . | Positive D-dimer without anticoagulation (N = 109) . | Positive D-dimer with anticoagulation (N = 373) . | P value . |
|---|---|---|---|---|---|---|
| Male sex, n (%) | 277 (52.5) | 283 (58.7) | .055 | 70 (64.2) | 213 (57.1) | .230 |
| Age (y), median (IQ) | 63 (45-75) | 69 (58-79) | <.0001 | 64 (49-72) | 71 (61-80) | <.0001 |
| Age >70 y, n (%) | 201 (38.1) | 223 (46.3) | .011 | 32 (29.3) | 191 (51.2) | <.0001 |
| Type of VTE, n (%) | ||||||
| Proximal DVT with no PE | 285 (54.5) | 244 (51.4) | .384 | 53 (49.1) | 191 (52.0) | .677 |
| DVT plus symptomatic PE | 97 (18.5) | 113 (23.8) | .037 | 26 (24.1) | 87 (23.7) | .968 |
| Isolated PE | 141 (27.0) (5 NA) | 118 (24.8) (7 NA) | .379 | 29 (26.8) (1 NA) | 89 (24.3) (6 NA) | .689 |
| Type of risk factors, n (%) | ||||||
| Idiopathic | 377 (71.4) | 394 (81.7) | <.0001 | 83 (76.1) | 311 (83.4) | |
| WRFs | 151 (28.6) | 88 (18.3) | <.0001 | 26 (23.9) | 62 (16.6) | .115 |
| Minor general, laparoscopic, or arthroscopic surgery | 7 | 2 | 1 | 1 | .115 | |
| Pregnancy or puerperium | 3 | 1 | 1 | 0 | ||
| Hormonal contraceptive replacement therapy | 90 | 30 | 11 | 19 | ||
| 8 | 2 | 1 | 1 | |||
| Long travel | 5 | 8 | 3 | 5 | ||
| Minor trauma, leg injury, reduced mobility | 17 | 20 | 8 | 13 | ||
| Hospitalization in a medical ward | 21 | 27 | 1 | 23 | ||
| Duration of previous anticoagulation, n (%) | ||||||
| ≤6 mo | 160 (30.3) | 141 (29.3) | .784 | 29 (26.6) | 112 (30.0) | .574 |
| 7-12 mo | 297 (56.2) | 272 (56.4) | 1.000 | 61 (56.0) | 211 (56.6) | .999 |
| >12 mo | 71 (13.5) | 69 (14.3) | .786 | 19 (17.4) | 50 (13.4) | .375 |
| Total duration of FU for all patients, y | 829 | 772 | 171 | 601 | ||
| FU, y, median (IQ) | 1.93 (1.25-2.00) | 1.90 (1.29-2.00) | .508 | 1.97 (1.23-2.00) | 1.88 (1.29-2.00) | .990 |
| Duration of FU, n | ||||||
| 2 y | 266 | 239 | 59 | 180 | ||
| 1-2 y | 169 | 165 | 29 | 136 | ||
| <1 y | 57* | 49 | 7 | 42 | ||
| Patients censored during FU, n (%) | 36 (6.8) | 29 (6.0) | .697 | 14 (12.8) | 15 (4.0) | .002 |
| Lost to FU, n (%) | 6 (1.1) | 1 (0.2) | .179 | 1 (0.9) | 0 | .535 |
| Presence of RVT (>4 mm), n (%) | 56 (10.6) | 63 (13.1) | .263 | 5 (4.6) | 58 (15.5) | .005 |
| Associated antiplatelet treatment, n (%) | 53 (10.0) | 42 (8.7) | .553 | 10 (9.2) | 32 (8.6) | .999 |
FU, follow-up; IQ, interquartile range; NA, not available.
Fifteen of these patients were included in the analysis (as intention-to-treat), though their serial D-dimer testing was still incomplete (being enrolled late) and/or had a short follow-up.