Clinical Decision Rules for Excluding Pulmonary Embolism: A Meta-analysis

BACKGROUND Clinical probability assessment is combined with d-dimer testing to exclude pulmonary embolism (PE). PURPOSE To compare the test characteristics of gestalt (a physician's unstructured estimate) and clinical decision rules for evaluating adults with suspected PE and assess the failure rate of gestalt and rules when used in combination with d-dimer testing. DATA SOURCES Articles in MEDLINE and EMBASE in English, French, German, Italian, Spanish, or Dutch that were published between 1966 and June 2011. STUDY SELECTION 3 reviewers, working in pairs, selected prospective studies in consecutive patients suspected of having PE. Studies had to estimate the probability of PE by using gestalt or a decision rule and verify the diagnosis by using an appropriate reference standard. DATA EXTRACTION Data on study characteristics, test performance, and prevalence were extracted. Reviewers constructed 2 × 2 tables and assessed the methodological quality of the studies. DATA SYNTHESIS 52 studies, comprising 55 268 patients, were selected. Meta-analysis was performed on studies that used gestalt (15 studies; sensitivity, 0.85; specificity, 0.51), the Wells rule with a cutoff value less than 2 (19 studies; sensitivity, 0.84; specificity, 0.58) or 4 or less (11 studies; sensitivity, 0.60; specificity, 0.80), the Geneva rule (5 studies; sensitivity, 0.84; specificity, 0.50), and the revised Geneva rule (4 studies; sensitivity, 0.91; specificity, 0.37). An increased prevalence of PE was associated with higher sensitivity and lower specificity. Combining a decision rule or gestalt with d-dimer testing seemed safe for all strategies, except when the less-sensitive Wells rule (cutoff value ≤4) was combined with less-sensitive qualitative d-dimer testing. LIMITATIONS Studies had substantial heterogeneity due to prevalence of PE and differences in threshold. Many studies (63%) had potential bias due to differential disease verification. CONCLUSION Clinical decision rules and gestalt can safely exclude PE when combined with sensitive d-dimer testing. The authors recommend standardized rules because gestalt has lower specificity, but the choice of a particular rule and d-dimer test depend on both prevalence and setting.