Clinical and laboratory features of rheumatic autoimmune disease associated cryoglobulinaemia

Abstract

Objective To investigate the clinical and laboratory features of autoimmune disease (AID) associated cryoglobulinaemia. Methods From April 2010 to May 2014, thirty three patients with AID in Peking University People's Hospital were tested positive for cryoglobulin. Their clinical and laboratory features were analyzed retrospectively. T test, Mann-Whitney U test, Chi-squaretest and Fisher's exact test were used for statistical analysis. Results Among the 33 patients, 26 were female, 7 were male, the average age was (47±17) years old (range 12-75 years old). The spectrum of autoimmune diseases included, in order, systemic lupus erythematosus (SLE), Sjogren's syndrome (SS), multiple myositis/dermatomyositis, rheumatoid arthritis (RA), systemic sclerosis (SSc), anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, antiphospholipid syndrome and primary biliary cirrhosis. SLE and SS accounted for 84.8% (28/33) in tpatients with cryoglobulinaemia. In patients withSLE, cryoglobulinaemia occurred at 2.0 (1.0-12.0) years after disease onset, and cryoglobulinpositive patients had more frequent renal involvement (71% vs 40%, P=0.004), positive anti-RNP (56% vs21%, P=0.007) and ACL (53% vs 8%, P=0.000). However, among patients with SS, cryoglobulinaemia occurred at 11.0 (4.0-18.0) years after disease onset, and cryoglobulin positive patients had higher rheumatoid factors (RF) [1 170(230.00, 2 800.00) U/ml vs 57.80(20.00, 230.50) U/ml, U=-0.002, P=0.001], IgM [3.54(1.83, 4.34) g/L vs 1.17(0.81, 2.26) g/L, U=0.016, P=0.014] and lower complement C3 [0.58(0.33, 0.68) g/L vs 0.81 (0.67, 0.98 g/L), U=0.004, P=0.003] and C4 [0.06 (0.03, 0.12) g/L vs 0.16 (0.12, 0.22), U= 0.017, P=0.016]. Conclusion Autoimmune disease complicated with oryoglo-bulinaemia is not uncommon in clinical practice, in which SLE and SS account for the leading two causes. Patients with positive anti-RNP and/ or ACL are positively associated with ciyoglobulinaemia. renal involvement of SLE is increased by the presence of cryoglobulin. Key words: Cryoglobulinemia; Autoimmune disease; Lupus erythematosus, systemic; Sjogren's syndrome