emDocs - November 19, 2015 - Author: Cassella C // Edited by: Koyfman A & Bright J
"Background
Pulmonary embolism is a life-threatening entity affecting up to 900,000 individuals a year. Per ACEP Clinical policy, there islevel B evidence the Wells score, Revised Geneva score, or clinical gestalt may be used to risk stratify patients with suspected PE. In low pretest probability patients, PERC may be utilized to exclude PE by H&P alone (level B).
(For a more thorough discussion of the PERC rule, see PERC Rule: Application and Limitations by Jason West.
Alternatively, there is level A evidence a negative D-dimer can be used to exclude PE in these low pretest probability patients. Furthermore, level C evidence states a negative D-dimer in the intermediate risk group can exclude PE.
Unfortunately, D-dimer levels increase with age decreasing the yield of the test. In order to increase the specificity safely, Douma et al. performed a retrospective analysis to derive age-adjusted D-dimer cutoffs. The study developed the age-adjusted D-dimer with a receiver operating characteristics (ROC) curve. In JAMA 2014, Righini et al. published a prospective study utilizing the age-adjusted cutoff.
AGE ADJUSTED D-DIMER CUTOFF = (AGE X 10) μg/L
**Applies to 50+ years old
Conclusions
A meta-analysis by Schouten et al. reviewed 13 retrospective studies (12,497 patients) investigating age-adjusted D-dimer published before June 21, 2012. All studies analyzed patients with non-high clinical probability scores. The pooled sensitivity of age-adjusted D-dimer was 97% or above for all age categories. Specificity was improved with the age-adjusted D-dimer in all age groups.
Age-adjusted D-dimer has been investigated in retrospective and some prospective studies. Although prospective trials are rare and no recent meta-analysis or clinical policy statement has been issued, there is an abundance of evidence that age-adjusted D-dimer increases specificity with minimal and acceptable decline in sensitivity in the low risk population."
http://www.emdocs.net/age-adjusted-d-dimer/