Research ArticleOriginal Research

Comparing the Diagnostic Performance of 2 Clinical Decision Rules to Rule Out Deep Vein Thrombosis in Primary Care Patients

Eit Frits van der Velde, Diane B. Toll, Arina J. ten Cate-Hoek, Ruud Oudega, Henri E. J. H. Stoffers, Patrick M. Bossuyt, Harry R. Büller, Martin H. Prins, Arno W. Hoes, Karel G. M. Moons and Henk C. P. M. van Weert
The Annals of Family Medicine January 2011, 9 (1) 31-36; DOI: https://doi.org/10.1370/afm.1198

Article Figures & Data

Tables

  • Table 1.

    Wells Rule and the Primary Care Rule Scoring to Rule Out Deep Vein Thrombosis (DVT)

    VariablesWells RulePrimary Care Rule
    Male sex–1
    Oral contraceptive use–1
    Presence of active malignancy (within last 6 mo)11
    Immobilization paresis/plaster lower extremities1–
    Major surgery (last 3 mo)11
    Absence of leg trauma–1
    Localized tenderness of deep venous system1–
    Dilated collateral veins (not varicose)11
    Swelling, whole leg1–
    Calf swelling ≥3 cm12
    Pitting edema confined to the symptomatic leg1–
    Previously documented DVT1–
    Alternative diagnosis at least as likely as DVT−2–
    Positive D-dimer result–6
    Cutoff scores for considering DVT as absent≤1≤3
  • Table 2.

    Concordance Between the Wells Rule and Primary Care Rule Without the D-Dimer Test

    Wells Rule
    Primary Care RuleHigh Score, ≥2 No. (%)Low Score, ≤1 No. (%)Total No. (%)
    High score, ≥4130 (13)22 (2)152 (15)
    Low score, ≤3243 (24)607 (61)850 (85)
    Total373 (37)629 (63)1,002 (100)
  • Table 3.

    Patients With Low Scores on Both Rules, With and Without a Negative D-Dimer Result, and (Missed) Thromboembolic Events

    Wells Rule (N=1,002)Primary Care Rule (N=1,002)
    OutcomeNo. (%)95% CINo. (%)95% CI
    CDR=clinical decision rule; CI=confidence interval; D-dimer = dimerized plasmin fragment D; VTE = venous thromboembolism (deep vein thrombosis or pulmonary embolism).
    Low CDR score without D-dimer629 (63)60–66850 (85)83–87
    Low CDR score and D-dimer negative447 (45)42–48495 (49)47–54
    VTE in patients with low score and D-dimer negative7 (1.6)0.4–2.77 (1.4)0.6–2.9

Additional Files

  • The Article in Brief

    Comparing the Diagnostic Performance of 2 Clinical Decision Rules to Rule Out Deep Vein Thrombosis in Primary Care Patients

    Eit Frits van der Velde , and colleagues

    Background The Wells clinical prediction rule for assessment of patients with suspected deep vein thrombosis is widely used, especially in secondary care settings. Recently, a new clinical decision rule for primary care patients has been proposed. This study compares the two rules on their ability to safely rule out a diagnosis of deep vein thrombosis among primary care patients and reduce the number of referrals for negative findings on leg ultrasound tests.

    What This Study Found Both clinical decision rules, when used in combination with a point-of-care D-dimer blood test, are effective and can spare almost half of patients an unnecessary referral for ultrasound. This study of 1,002 patients with possible deep vein thrombosis found a venous thromboembolic event occurred during follow-up in 7 patients with a low score and a negative blood test, both with the Wells rule and primary care rule. Direct medical costs per patient were about the same using both rules. Using the Wells rule, 447 patients (45 percent) would not need referral for further testing compared with 495 (49 percent) when using the primary care rule.

    Implications

    • The authors suggest that the primary care rule, which prevents slightly more unnecessary ultrasound procedures than the Wells rule, is somewhat more convenient for both patients and physicians.
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