Abstract
Recent, large cohort studies have shown that using a higher, age-adjusted D-dimer value (with a highly sensitive ELISA assay) can safely exclude venous thromboembolic (VTE) disease in the over 50’s. We investigated if we were able to apply the same principle locally, using a semi-quantitative latex agglutination assay (INNOVANCE d-dimer).
We reviewed the casenotes of patients aged over 50 assessed in our hospital who had a positive d-dimer (>420 µg/L) over a 1 year period (2011) to determine the results of investigation for VTE if performed. We then considered the two proposed age adjusted cut-offs (AAC) - age x 10 µg/L in the over 50’s (AAC1) and an absolute cut-off of >750 µg/L in the over 60’s (AAC2). We determined the frequency of VTE detection in both groups.
Over 1 year 1324 d-dimers were requested in the over 50 age group. 874 were positive (>420 µg/L). 202 patients had a d-dimer within AAC1 - 124 patients had negative investigations for VTE (42 CTPA, 104 leg USS), 1 positive investigation (below knee DVT) and 77 patients not investigated. 232 patients had a d-dimer within AAC2 - 162 had negative investigation for VTE (49 CTPA, 116 leg USS), 1 positive (below knee DVT, same patient as in AAC1) and 69 patients not investigated. Overall therefore applying the age adjusted D-dimer thresholds would have missed 1 VTE event (of arguable significance).
Applying previously validated age-adjusted D-dimer cut-offs appears to be safe with the INNOVANCE D-dimer assay. This has been integrated into practice in our hospital, reducing the burden on radiology and improving length of stay for patients with suspected VTE.
- © 2013 ERS
