Background: This study assessed the value of C-reactive protein as a predictor of disease severity and response to infliximab therapy in patients with chronic pulmonary sarcoidosis.
Design: Sera were collected through week 52 from 138 patients with chronic pulmonary sarcoidosis who received placebo or infliximab in a randomized, double-blind, placebo-controlled study. We evaluated the response to therapy by baseline CRP using a dichotomous cutpoint (0.8 mg/dL) for the change from baseline in percent-predicted forced vital capacity (FVC), Saint George's Respiratory Questionnaire (SGRQ), 6-minute walk distance (6MWD), Borg's CR10 dyspnea score, and Physician Organ Assessment (POA).
Results: CRP was elevated in 36% of patients at baseline, and was significantly reduced by infliximab by week 2. Among patients with elevated baseline CRP, infliximab-treated patients improved significantly compared with placebo-treated patients in percent-predicted FVC (+2.5 versus -2.6%), 6MWD (+8.0 versus -34.1), Borg's CR10 dyspnea score (pre-6MWD -0.8 versus +0.9, post-6MWD -1.1 versus +0.8), and POA (-3.1 versus -0.3). Patients with lower CRP levels at baseline did not show significant differences between the placebo and infliximab groups in most endpoints evaluated.
Conclusions: In chronic sarcoidosis patients, elevated CRP appears to identify a subset with more severe disease who may respond better to treatment with infliximab.
Trial registration: ClinicalTrials.gov NCT00073437.