917
D-Dimer Levels May Identify Chronic Urticaria Patients Who Would More Likely Fail H2 Blockers or Omalizumab
Monday, March 7, 2016: 2:00 PM
Room 515A (Convention Center)
Tho Q. Truong, MD
Rationale: Several studies support that activation of the extrinsic coagulation pathway occurs in patients with chronic urticaria (CU).  It has been suggested that elevated plasma levels of D-dimer may also correlate to the clinical severity of CU.  Our purpose was to determine whether or not plasma D-dimer should be studied as a marker for treatment failure to H2 blockers and/or omalizumab.  Identifying patients who would likely fail the traditional initial line of therapies in the early stages of their presentation may advance them to the next line of therapies sooner, and spare them unnecessary treatments or prolonged disease activity.

Methods: Six patients with chronic urticaria (by skin biopsy and clinical criteria) where studied; their response to antihistamines and omalizumab, as well as serum D-dimer levels (by ELISA) and other laboratories were recorded. 

Results: All but one of our CU patients who had failed both H2 blockers and omalizumab (n= 6) had significant D-dimer elevation during a flare of their urticaria (mean = 2670 ng/mL, median = 3295 ng/mL, normal reference <600 ng/mL). Patients with CU but who responded to H2 antihistamines and/or to omalizumab, and who had d-dimer coincidently checked for other concerns during an urticarial flare (n=4), did not have elevations in D-dimer (mean = 336 ng/mL, median =  342 ng/mL).

Conclusions: Though CU patients with a normal D-dimer may also fail first line therapies, this study suggests that CU patients with significantly elevated D-dimer may be more likely to fail first line therapies, and that further study of D-dimer and other laboratory indicators of complement activation should be studied as markers for first line treatment failure in CU.