Correlation between plasma D-dimer levels and the severity of patients with chronic urticaria

Background: Beside autoimmunity, coagulation pathway is also involved in the pathogenesis of chronic urticaria (CU). Previous studies showed that plasma D-dimer levels paralleled the severity of the disease. To date, there are no data concerning D-dimer level in Thai patients with CU. Objective: This study aimed to find the relationship between plasma D-dimer levels and the disease severity of Thai CU patients. The secondary objective is to analyze plasma D-dimer level in each group of patients who performed autologous plasma skin testing (APST) and autologous serum skin testing (ASST). Methods: We retrospectively reviewed case record forms of chronic idiopathic urticaria (CIU) patients aged at least 18 years in Skin Allergy Clinic, Siriraj Hospital Mahidol University, Bangkok, during June 2008 to June 2011. Results: Of 120 patients, plasma D-dimer level was abnormal in 58 patients (48.3%). The study showed statistically significant positive correlation between disease severity and plasma D-dimer level (p < 0.05, r = 0.537). There was no statistically significant difference in plasma D-dimer level between APST positive and negative groups, and also between ASST positive and negative groups. In APST negative group, plasma D-dimer level was elevated in 29 patients (47.5%) and correlated with disease severity. Conclusion: This study showed elevated plasma D-dimer levels in nearly half of Thai patients with CIU. There was a positive correlation between plasma D-dimer levels and the severity of disease activity. Investigation for plasma D-dimer level may be an alternative way to evaluate disease severity in patients with CIU.