The clinical importance of the anti-Ro antibody has not been completely understood. This study investigated identification of the association between mortality and clinical features in patients with autoimmune rheumatic diseases and detectable anti-Ro antibody titers.
We retrospectively analyzed a total of 336 patients with autoimmune rheumatic diseases and positive anti-Ro antibody titers from January 2012 to January 2015. Clinical manifestations and other autoantibodies detected during the follow-up period were identified. Cumulative survival rates were assessed by Kaplan-Meier analysis. Differences between survival curves for each risk factor were analyzed by log-rank test. The relative risk of mortality was assessed using standardized mortality ratios (SMRs).
There was no difference in the mortality rates of patients with autoimmune rheumatic diseases with or without detectable anti-Ro antibody (SMR: 1.373, 95% CI: 0.539-2.791). Six patients (4 with systemic lupus erythematosus [SLE] and two with Sjögren's syndrome [SS]) died during the follow-up period. In the whole study population, the mortality rate of patients with lymphopenia was higher than those without lymphopenia (P = 0.023). In a sub-group of patients with both SLE and SS, Kaplan-Meier analysis showed that lymphopenia and interstitial lung disease were associated with increased mortality (P = 0.024 and P = 0.023, respectively).
This study demonstrated that presence of the anti-Ro antibody was not associated with increased mortality in patients with autoimmune rheumatic disease. Conversely, we found that lymphopenia was independently associated with mortality in patients with autoimmune rheumatic disease.