Clinical Prediction

“Based on the results of our own work, the Wells [clinical prediction rule for DVT] used in primary care setting demonstrated a high degree of accuracy. In patients with high probability of [Deep Vein Thrombosis (DVT)] assessed by Wells scoring index ultrasonography of deep veins should be performed without delay and regardless of prior determination of D-dimer level.”Dybowska M, Tomkowski WZ, Kuca P, et al.

Rahiminejad M, Rastogi A, Prabhudesai S, et al. Evaluating the Use of a Negative D-Dimer and Modified Low Wells Score in Excluding above Knee Deep Venous Thrombosis in an Outpatient Population, Assessing Need for Diagnostic Ultrasound. ISRN Radiol. 2014 Mar 9;2014:519875. eCollection 2014.

“In our outpatients with suspected lower limb DVT, a combination of no clinical risk factors, negative D-dimer, and low Wells score can reliably exclude an above knee DVT and there is no need for US imaging in these patients. We recommend that outpatients with a clinical risk factor for DVT or a moderate or high Wells score should be imaged.”Rahiminejad M, Rastogi A, Prabhudesai S, et al.

Bates SM, Jaeschke R, Stevens SM, et al. Diagnosis of DVT: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb;141(2 Suppl):e351S-418S.

“Favored strategies for diagnosis of first DVT combine use of pretest probability assessment [via Wells clinical prediction rule for DVT], D-dimer, and US. There is lower-quality evidence available to guide diagnosis of recurrent DVT, upper extremity DVT, and DVT during pregnancy.”Bates SM, Jaeschke R, Stevens SM, et al.

Qaseem A, Snow V, Barry P, et al. Current Diagnosis of Venous Thromboembolism in Primary Care: A Clinical Practice Guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med. 2007 Jan; 5(1): 57–62.

“Strong evidence supports the use of clinical prediction rules to establish pretest probability of [Venous Thromboembolism (VTE)] before further testing. Use of a high-sensitivity D-dimer assay in patients who have a low pretest probability of VTE has a high negative predictive value; it is highest for younger patients with low pretest probability, no associated comorbidity or previous DVT, and a short duration of symptoms.”Qaseem A, Snow V, Barry P, et al.

Wells PS, Owen C, Doucette S, et al. Does this patient have deep vein thrombosis? JAMA. 2006 Jan 11;295(2):199-207.

“Diagnostic accuracy for DVT improves when clinical probability is estimated before diagnostic tests. Patients with low clinical probability on the predictive rule have prevalence of DVT of less than 5%. In low-probability patients with negative D-dimer results, diagnosis of DVT can be excluded without ultrasound; in patients with high clinical suspicion for DVT, results should not affect clinical decisions.”Wells PS, Owen C, Doucette S, et al.

Oudega R, Hoes AW, Moons KG. The Wells rule does not adequately rule out deep venous thrombosis in primary care patients. Ann Intern Med. 2005 Jul 19;143(2):100-7.

“In conclusion, we found that the Wells [clinical prediction rule for DVT], alone or in combination with d-dimer testing, does not guarantee accurate estimation of risk in primary care patients in whom DVT is suspected. Because of the apparent differences between primary and secondary care, a diagnostic rule combining patient history, physical examination, and d-dimer assay findings that has been developed using only primary care patients is of more value.”Oudega R, Hoes AW, Moons KG.

Wells PS, Anderson DR, Rodger M, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003 Sep 25;349(13):1227-35.

“This study confirms the validity of modifying our previous clinical [prediction rule for DVT], which categorized patients into high-, moderate-, and low-probability groups, to one that categorizes patients as likely or unlikely to have deep-vein thrombosis. The addition to the scoring system of one point for a previous diagnosis of deep-vein thrombosis allows the model to be used in patients with previous thrombosis, a group we had excluded from earlier studies.”Wells PS, Anderson DR, Rodger M, et al.

Kilroy D, Ireland S, Reid P, et al. Emergency department investigation of deep vein thrombosis. Emerg Med J. 2003 Jan; 20(1): 29–32.

“…DVT is a difficult condition to diagnose clinically. Application of the Wells [clinical prediction rule for DVT] to patients in our department permitted stratification into high, moderate, and low risk groups (prevalence of DVT 58.3%, 8.9%, and 1.5% respectively). This is not as discriminatory as Wells’ original data and may be explained by insufficient ongoing training or interobserver variation within our staff.”Kilroy D, Ireland S, Reid P, et al.

Walsh K, Kelaher N, Long K, Cervi P. An algorithm for the investigation and management of patients with suspected deep venous thrombosis at a district general hospital. Postgrad Med J. 2002 Dec; 78(926): 742–745.

“This study has shown that the negative predictive value of a low clinical pre-test score alone is 92%. The negative predictive value of a normal D-dimer alone (at a cut off for normal [less than] 400 units) is 96%. The negative predictive value of the combination of a low clinical pre-test score and D-dimer [less than] 400 units is 100%.”Walsh K, Kelaher N, Long K, Cervi P.