Lisette van Dam

Wells rule and D-dimer test in recurrent ipsilateral DVT 4 63 Table 1. Clinical decision rule according the original and modified Wells rule for deep vein thrombosis (DVT) Clinical characteristics Score Active cancer (Treatment or palliation within 6 months) 1 Bedridden recently > 3 days or major surgery within 12 weeks 1 Calf swelling > 3 cm compared to the other leg 1 Collateral (non-varicose) superficial veins present 1 Entire leg swollen 1 Localized tenderness along the deep venous system 1 Pitting edema, confined to symptomatic 1 Paralysis, paresis or recent plaster immobilization of the lower extremity 1 Previously documented DVT* 1 Alternative diagnosis of DVT as likely or more likely -2 Note: Cu t‐ off points for both original and modified Wells rule: unlikely clinical probability (0 ‐ 1 point), likely clinical probability (≥2 points). * Criterion added for the modified Wells rule. For the secondary outcome, we repeated the analysis of the primary outcome in patients on anticoagulant treatment at baseline. Next, we evaluated the effect of applying the combination of CDR assessment and D-dimer measurement to the diagnostic work-up of suspected recurrent DVT on the number of required diagnostic imaging tests to three diagnostic algorithms including imaging with MRDTI and/or CUS. Scenario 1-3 included diagnostic algorithms consisting only of imaging tests. In the first scenario, MRDTI would have been performed in all patients (as was performed in the Theia study population). In the second scenario, all patients with suspected recurrent ipsilateral DVT would have been referred for CUS with MRDTI only to be performed in case of an abnormal CUS. In the third scenario, the same diagnostic algorithm was used, but MRDTI would have been restricted to patients with an inconclusive CUS. In scenario 4-6 the original and modified Wells rule in combination with D-dimer testing was added as initial step of scenarios 1-3 ( Figure 2 ). The difference in the number of required imaging tests between the scenarios was calculated. All analyses were performed with the use of SPSS software, version 25.0.