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Objective To assess the accuracy of the Wells rule for excluding deep vein thrombosis and whether this accuracy applies to different subgroups of patients.Design Meta-analysis of individual patient data. Data sources Authors of 13 studies (n=10 002) provided their datasets, and these individual patient data were merged into one dataset.Eligibility criteria Studies were eligible if they enrolled consecutive outpatients with suspected deep vein thrombosis, scored all variables of the Wells rule, and performed an appropriate reference standard.Main outcome measures Multilevel logistic regression models, including an interaction term for each subgroup, were used to estimate differences in predicted probabilities of deep vein thrombosis by the Wells rule. In addition, D-dimer testing was added to assess differences in the ability to exclude deep vein thrombosis using an unlikely score on the Wells rule combined with a negative D-dimer test result.Results Overall, increasing scores on the Wells rule were associated with an increasing probability of having deep vein thrombosis. Estimated probabilities were almost twofold higher in patients with cancer, in patients with suspected recurrent events, and (to a lesser extent) in males. An unlikely score on the Wells rule (≤1) combined with a negative D-dimer test result was associated with an extremely low probability of deep vein thrombosis (1.2%, 95% confidence interval 0.7% to 1.8%). This combination occurred in 29% (95% confidence interval 20% to 40%) of patients. These findings were consistent in subgroups defined by type of D-dimer assay (quantitative or qualitative), sex, and care setting (primary or hospital care). For patients with cancer, the combination of an unlikely score on the Wells rule and a negative D-dimer test result occurred in only 9% of patients and was associated with a 2.2% probability of deep vein thrombosis being present. In patients with suspected recurrent events, only the modified Wells rule (adding one point for the previous event) is safe.Conclusion Combined with a negative D-dimer test result (both quantitative and qualitative), deep vein thrombosis can be excluded in patients with an unlikely score on the Wells rule. This finding is true for both sexes, as well as for patients presenting in primary and hospital care. In patients with cancer, the combination is neither safe nor efficient. For patients with suspected recurrent disease, one extra point should be added to the rule to enable a safe exclusion.

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Key Points Immunoassays used to diagnose heparin-induced thrombocytopenia vary substantially with regard to the specific test characteristics. High sensitivity (>95%) in combination with high specificity (>90%) was found in only 5 tests.

To cite this article: van Doormaal FF, Terpstra W, van der Griend R, Prins MH, Nijziel MR, van de Ree MA, Bü ller HR, Dutilh JC, ten Cate-Hoek A, van den Heiligenberg SM, van der Meer J, Otten JM. Is extensive screening for cancer in idiopathic venous thromboembolism warranted? J Thromb Haemost 2011; 9: 79-84.Summary. Background: Patients with a first episode of idiopathic venous thromboembolism (IVTE) have an estimated 10% incidence of cancer within 12 months after diagnosis. However, the utility of screening for cancer in this population is controversial. Methods: In this prospective concurrently controlled cohort study, limited and extensive cancer screening strategies were compared. All 630 patients underwent baseline screening consisting of history, physical examination, basic laboratory tests and chest X-ray. In the extensive screening group abdominal and chest CT scan and mammography were added. Outcomes were incidence and curability of cancer, and cancer-related and overall mortality. Results: In 12 of the 342 (3.5%) patients in the extensive screening group malignancy was diagnosed at baseline compared with 2.4% (seven of 288 patients) in the limited screening group. Extensive screening detected six additional cancers (2.0%; 95% CI, 0.74-4.3), of which three were potentially curable. During a median 2.5 years of follow-up, cancer was diagnosed in 3.7% and 5.0% in the extensive and limited screening groups, respectively. In the extensive screening group 26 patients (7.6%) died compared with 24 (8.3%) in the limited screening group; adjusted hazard ratio 1.22 (95% CI, 0.69-2.22). Of these deaths 17 (5.0%) in the extensive screening group and 8 (2.8%) in the limited screening group were cancer related; adjusted hazard ratio 1.79 (95% CI, 0.74-4.35). Conclusions: The low yield of extensive screening and lack of survival benefit do not support routine screening for cancer with abdominal and chest CT scan and mammography in patients with a first episode of IVTE.