LAUSR

Background Systemic lupus erythematosus (SLE), as the prototype of systemic autoimmune diseases, has a wide array of clinical manifestations. An association between cryoglobulinemia and certain clinical and immunological features of SLE has been proposed, and there are various physiopathologic pathways that could be involved in this relationship. Although the presence of cryoglobulinemia in SLE patients may be related to specific disease features and could even have prognostic value, this association has not been addressed thoroughly. Objectives To describe clinical and immunological characteristics in SLE patients with cryoglobulinemia. Methods We performed a retrospective, case-control study, in which we included all patients with a cryoglobulin determination between January 2005 and December 2016 in a third level referral centre in Mexico City. Patients with SLE and a positive cryoglobulin test (cryocrit ≥1%) were included in the case group, whereas SLE patients with a negative cryoglobulin determination were considered controls. We studied demographic, clinical and immunological characteristics at the time of the positive cryoglobulin result, as well as three months earlier, and 6 and 12 months later. Results Thirty-six SLE patients had a cryoglobulin determination throughout the study period. Ten patients had cryoglobulin levels≥1% and were included in the case group, whereas 26 patients with a negative determination were included as controls. Mean age was 37.7±18.3 in cases and 41.7±19.3 in controls. 70% of cases and 88.5% of controls were women. Among subjects with cryoglobulinemia, the cryocrit was 1% in 9 patients, and 3% in one. Regarding clinical and immunological characteristics, a positive lupus anticoagulant and a history of vasculitis were more frequent in patients with serum cryoglobulins (p=0.004 and 0.04, respectively). At the time of the cryoglobulin measurement, patients in the case group had lower levels of C3 and C4 (p=0.026 and p=0.003, respectively), and serum albumin (p=0.028). They also had a higher prevalence of serositis (p=0.021) and peripheral oedema (p=0.034), as well as a higher SLICC Damage Index score (p=0.014) than controls. Regarding follow-up, patients in the case group had a higher SLEDAI score after six and twelve months (p=0.009 and 0.034, respectively). Also, after 12 months they had a higher prevalence of renal activity (p=0.004) and lower C4 levels (p=0.001). Among patients with renal activity, 20% of cases and 55% of controls had achieved complete remission after 12 months. Conclusions Serum cryoglobulins in SLE patients were associated with positive lupus anticoagulant and hypocomplementemia. Cryoglobulinemia was also associated with specific disease manifestations, such as serositis and vasculitis, and with damage accrual. At follow-up, patients with cryoglobulinemia had a higher prevalence of renal activity, as well as an increased disease activity overall. Whether cryoglobulins could be used as a biomarker for renal activity or worse renal prognosis remains to be determined, and larger prospective studies will be needed to address this possibility. Disclosure of Interest None declared