title: 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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  MEDLINE and EMBASE from 1 January 1988 to 13 February 2016.
  
  
  METHODS
  6 prospective studies in which the diagnostic management of PE was guided by the dichotomized Wells rule and quantitative d-dimer testing.
  
  
  METHODS
  Individual data of 7268 patients; risk of bias assessed by 2 investigators with the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  Post hoc analysis, between-study differences in patient characteristics, use of various d-dimer assays, and limited statistical power to assess failure rate.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  None.
authors.forename: Nick
authors.initials: N
authors.lastname: van Es
authors.forename: Tom
authors.initials: T
authors.lastname: van der Hulle
authors.forename: Josien
authors.initials: J
authors.lastname: van Es
authors.forename: Paul L
authors.initials: PL
authors.lastname: den Exter
authors.forename: Renée A
authors.initials: RA
authors.lastname: Douma
authors.forename: Robbert J
authors.initials: RJ
authors.lastname: Goekoop
authors.forename: Inge C M
authors.initials: IC
authors.lastname: Mos
authors.forename: Javier
authors.initials: J
authors.lastname: Galipienzo
authors.forename: Pieter W
authors.initials: PW
authors.lastname: Kamphuisen
authors.forename: Menno V
authors.initials: MV
authors.lastname: Huisman
authors.forename: Frederikus A
authors.initials: FA
authors.lastname: Klok
authors.forename: Harry R
authors.initials: HR
authors.lastname: Büller
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Bossuyt
mesh_terms: D000367:Age Factors; D000465:Algorithms; D003661:Decision Support Techniques; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D009369:Neoplasms / Q000150:complications; D011336:Probability; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis*; D054556:Venous Thromboembolism / Q000150:complications
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D