Table 4.
Comparison of study characteristics, participant characteristics, HERDOO2 predictor variable distribution, and primary outcome event rates in HERDOO2 derivation study and current HERDOO2 validation study. Values are numbers affected/Total numbers in sample (percentage) unless stated otherwise
| Variables | Derivation study (n=646) | Validation study (n=2747) |
|---|---|---|
| Study characteristics | ||
| Study design | Prospective cohort | Prospective cohort |
| Timeline | 2001-06 | 2008-15 |
| Setting | 12 tertiary centres in four countries | 44 secondary and tertiary centres in seven countries |
| Inclusion criteria | First objectively proved; unprovoked* major VTE† treated with anticoagulants for 5-7 months | First objectively proved; unprovoked* major VTE† treated with anticoagulants for 5-12 months |
| Exclusion criteria | Recurrent VTE during treatment; discontinued anticoagulants; require ongoing anticoagulants; known “high risk” thrombophilia | Recurrent VTE during treatment; discontinued anticoagulants; require ongoing anticoagulants; known “high risk” thrombophilia; plan on using exogenous oestrogen after stopping anticoagulants; pregnancy associated index VTE event |
| Primary outcome | Blind independent adjudicated recurrent major VTE† compared with baseline imaging | Blind independent adjudicated recurrent major VTE† compared with baseline imaging |
| Anticoagulation treatment after enrolment | Stopped in all participants | Low risk women
(0 or 1 HERDOO2 criteria): anticoagulants stopped per
protocol High risk women and men (≥2 HERDOO2 criteria): anticoagulant decision left to clinicians and patients (ie, observation only) (84.8% continued anticoagulants) |
| Mean follow-up (months) | 18.0 | 11.6 |
| Participant characteristics | ||
| Men | 332/646 (51.4) | 1534/2747 (55.8) |
| Mean age (years) | 52.5 | 54.4 |
| White | 597/646 (92.4) | 2287/2734 (83.7) |
| Women with oestrogen associated index VTE | 73/322 (22.6) | 397/1213 (32.7) |
| Index VTE type: | ||
| Isolated DVT | 339/646 (52.5) | 1113/2747 (40.5) |
| Isolated PE | 194/646 (30.0) | 1068/2747 (38.9) |
| DVT and PE | 113/646 (17.5) | 566/2747 (20.6) |
| HERDOO2 predictors in female participants at baseline examination: | ||
| Hyperpigmentation, oedema, or redness in either leg | 96/260 (36.9) | 295/1213 (24.3) |
| D-dimer ≥250 μg/L during anticoagulant use | 121/304 (39.8) | 604/1201 (50.3) |
| Older age, ≥65 years | 87/314 (27.7) | 390/1213 (32.2) |
| Obesity with BMI ≥30 | 114/313 (36.4) | 521/1213 (43.0) |
| HERDOO2 criteria present: | ||
| 0 or 1 | 164/314 (52.2) | 622/1213 (51.3) |
| ≥2 | 150/314 (47.8) | 591/1213 (48.7) |
| Primary outcome event rates (recurrent major VTE (%) per 100 patient years (95% CI) (No affected)): | ||
| All | 9.3 (7.7 to 11.3) | 2.6 (2.1 to 3.3) |
| Men: | ||
| Discontinue anticoagulants | 13.7 (10.8 to 17.0) (n=332) | 8.4 (5.0 to 13.2) (n=222) |
| Continue anticoagulants | - (n=0) | 1.2 (0.7 to 2.0) (n=1312) |
| High risk women (≥2 HERDOO2 criteria): | ||
| Discontinue anticoagulants | 14.1 (10.9 to 17.3) (n=150) | 7.4 (3.0 to 15.3) (n=101) |
| Continue anticoagulants | - (n=0) | 2.5 (1.3 to 4.4) (n=490) |
| Low risk women (0 or 1 of the HERDOO2 criteria): | ||
| Discontinue anticoagulants | 1.6 (0.3 to 4.6) (n=164) | 3.0 (1.8 to 4.8) (n=591) |
| Continue anticoagulants | - (n=0) | 0.0 (0.0 to 12.3) (n=31) |
VTE=venous thromboembolism; DVT=deep vein thrombosis; PE=pulmonary embolism; BMI=body mass index.
*Absence of leg fracture or leg cast or major surgery in past three months, and no malignancy in past five years.
†Proximal DVT and/or segmental or greater PE.