C-reactive protein is linked to disease activity, impact, and response to treatment in patients with chronic spontaneous urticaria.

BACKGROUND: Elevated levels of C-reactive protein (CRP), a sensitive marker of inflammation, have been consistently reported in chronic spontaneous urticaria (CSU). Here, we retrospectively analyzed data from 1253 CSU patients from 2 centers to answer the following questions: (i) What is the prevalence of elevated levels of CRP in CSU? (ii) Why do CSU patients show elevated levels of CRP? (iii) Are elevated CRP levels relevant?

METHODS: Serum levels of CRP were measured by the nephelometric method. We collected information regarding various laboratory tests including ESR, CBC with differential, D-dimer, fibrinogen, C3, C4, IL-6, etc. For most patients, we also collected data on age, gender, duration of CSU, presence of angioedema, activity (UAS at the time of blood sampling and for 7 days), quality of life (CU-Q2oL and/or DLQI), comorbidities and possible causes of CSU, and autologous serum skin test (ASST) response. The efficacy of second-generation antihistamines was evaluated on the day of blood collecting.

RESULTS: One-third of CSU patients had elevated levels of CRP. Higher levels of CRP were associated with ASST positivity (P = .009) and arterial hypertension (P = .005), but not with other possible causes or comorbidities of CSU. C-reactive protein correlated with urticaria activity (P < .001), quality of life impairment (P = .026), and inflammatory and coagulation markers (P < .001). C-reactive protein levels were significantly higher in nonresponders to antihistamines as compared to responders (P < .001).

CONCLUSION: Elevated levels of CRP are common and relevant in CSU patients. The assessment of CRP levels may help to optimize the management of patients with CSU.