Absence of a positive correlation between CRP and leptin in rheumatoid arthritis

Aims: Rheumatoid Arthritis (RA) is a model of chronic inflammatory disease. In this study we evaluated the correlation of leptin and CRP in patients with RA and normal controls. Main methods: A total of 75 patients with RA and 40 healthy adults were recruited in this case-control study. RA patients were categorized into high (DAS-28 > 3.2) and low activity (DAS <= 3.2) group according to their DAS-28 score. Key findings: Leptin level was significantly correlated with CRP in healthy controls (r = 0.365; p < 0.05), but this correlation was lost in RA patients (r = 0.095, p = 0.41). Patients with RA had higher serum leptin levels compared to healthy controls (P < 0.01). No difference in serum leptin level was observed between patients with high and low activity disease. Also leptin was correlated with BMI in healthy controls (r = 0.326, p = 0.037). This correlation was not present in RA patients (r = 0.039, p = 0.756). Significance: We observed that the physiologic correlation between leptin and CRP and BMI and CRP was not present RA patients. This is a new study reporting the lost correlation between leptin and CRP in RA patients.