To study the level of high-sensitivity C-reactive protein (hsCRP) and its relationship with disease activity, damage, and cardiovascular risk factors in patients with systemic lupus erythematosus (SLE).
Consecutive patients who fulfilled ≥4 American College of Rheumatology criteria for SLE who did not have a concurrent infection were recruited. Blood was assayed for hsCRP level, and disease activity, organ damage of SLE, and cardiovascular risk factors were assessed. Linear regression analyses were performed for the relationship between hsCRP levels, SLE activity, damage, and cardiovascular risk factors.
In total, 289 patients were studied (94% women, mean ± SD age 39.0 ± 13.1 years, and mean ± SD SLE duration 7.8 ± 6.7 years). The mean ± SD Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score was 4.9 ± 5.6 and clinically active SLE was present in 122 patients (42%). The mean ± SD hsCRP level was 4.87 ± 12.7 mg/liter, and 28 patients with active SLE (23%) had an undetectable hsCRP level (<0.3 mg/liter). The linear regression analyses revealed a significant correlation between hsCRP level and musculoskeletal disease (β = 0.21), hematologic disease (β = 0.19), active serositis (β = 0.46), and clinical SLEDAI score (β = 0.24) after adjusting for age, sex, body mass index, serum creatinine, and the use of various medications (P < 0.005 for all). hsCRP levels correlated significantly with anti-double-stranded DNA titer (β = 0.33, P < 0.001) but did not correlate with complement C3 (β = -0.07, P = 0.26). An hsCRP level >3 mg/liter was significantly associated with male sex, long-term smoking, diabetes mellitus, a higher atherogenic index, and a history of arterial thrombosis. hsCRP levels correlated significantly with pulmonary and endocrine damage scores.
hsCRP was detectable in 77% of SLE patients with clinically active disease and correlated with SLEDAI scores, particularly in serositis and in the musculoskeletal and hematologic systems. Elevated hsCRP levels in SLE were associated with certain cardiovascular risk factors and a history of arterial thromboembolism.