Serum C-reactive protein levels can predict organ damage in patients with SLE with the lupus low disease activity state

ObjectivesThe importance of low detectable C-reactive protein (CRP) levels in patients with systemic lupus erythematosus (SLE) remains unclear. This study aimed to examine the association between CRP levels and damage accrual in SLE patients with low disease activity.MethodsPatients with SLE who met the criteria for lupus low disease activity state (LLDAS) at registration were divided into two groups: serum CRP levels consistently >1.0 mg/L (high CRP group) or ≤1.0 mg/L (low CRP group) at both registration and the first year. Damage accrual was assessed by evaluating the increase in the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI).ResultsAmong the 276 patients, 81 were in the high CRP group and 195 were in the low CRP group. Patients in the high CRP group were older, included a lower proportion of women and individuals using hydroxychloroquine, and had higher body mass index and SDI values at baseline. CRP categories were not associated with SDI progression (HR: 1.40, 95% CI: 0.85-2.31), whereas older patients were more likely to experience damage accrual (HR: 1.03, 95% CI: 1.01-1.05, p = 0.002). In the subgroup analysis limited to younger patients, the high CRP group showed more SDI progression (HR: 2.91, 95% CI: 1.21-7.03, p = 0.017).ConclusionCRP levels were associated with SDI progression in younger patients with LLDAS. Even in patients with inactive SLE, positive CRP levels may indicate the need to modify the treatment for SLE and reassess atherosclerotic risk factors.