Wells Rule and d-Dimer Testing to Rule Out Pulmonary Embolism: A Systematic Review and Individual-Patient Data Meta-analysis.

ABSTRACT

BACKGROUND: The performance of different diagnostic strategies for pulmonary embolism (PE) in patient subgroups is unclear. PURPOSE: To evaluate and compare the efficiency and safety of the Wells rule with fixed or age-adjusted d-dimer testing overall and in inpatients and persons with cancer, chronic obstructive pulmonary disease, previous venous thromboembolism, delayed presentation, and age 75 years or older. DATA SOURCES MEDLINE and EMBASE from 1 January 1988 to 13 February 2016. STUDY SELECTION 6 prospective studies in which the diagnostic management of PE was guided by the dichotomized Wells rule and quantitative d-dimer testing. DATA EXTRACTION Individual data of 7268 patients; risk of bias assessed by 2 investigators with the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool. DATA SYNTHESIS: The proportion of patients in whom imaging could be withheld based on a "PE-unlikely" Wells score and a negative d-dimer test result (efficiency) was estimated using fixed (≤500 µg/L) and age-adjusted (age × 10 µg/L in patients aged >50 years) d-dimer thresholds; their 3-month incidence of symptomatic venous thromboembolism (failure rate) was also estimated. Overall, efficiency increased from 28% to 33% when the age-adjusted (instead of the fixed) d-dimer threshold was applied. This increase was more prominent in elderly patients (12%) but less so in inpatients (2.6%). The failure rate of age-adjusted d-dimer testing was less than 3% in all examined subgroups. LIMITATION: Post hoc analysis, between-study differences in patient characteristics, use of various d-dimer assays, and limited statistical power to assess failure rate. CONCLUSION: Age-adjusted d-dimer testing is associated with a 5% absolute increase in the proportion of patients with suspected PE in whom imaging can be safely withheld compared with fixed d-dimer testing. This strategy seems safe across different high-risk subgroups, but its efficiency varies. PRIMARY FUNDING SOURCE None.