Comorbidities in Patients With Primary Sjögren's Syndrome and Systemic Lupus Erythematosus: A Comparative Registries-Based Study

Objective: To compare the prevalence of the main comorbidities in 2 large cohorts of patients with primary Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE), with a focus on cardiovascular (CV) diseases.

Methods: This was a cross-sectional multicenter study where the prevalence of more relevant comorbidities in 2 cohorts was compared. Patients under followup from SJOGRENSER (Spanish Rheumatology Society Registry of Primary SS) and RELESSER (Spanish Rheumatology Society Registry of SLE), and who fulfilled the 2002 American-European Consensus Group and 1997 American College of Rheumatology classification criteria, respectively, were included. A binomial logistic regression analysis was carried out to explore potential differences, making general adjustments for age, sex, and disease duration and specific adjustments for each variable, including CV risk factors and treatments, when appropriate.

Results: A total of 437 primary SS patients (95% female) and 2,926 SLE patients (89% female) were included. The mean age was 58.6 years (interquartile range [IQR] 50.0-69.9 years) for primary SS patients and 45.1 years (IQR 36.4-56.3 years) for SLE patients (P < 0.001), and disease duration was 10.4 years (IQR 6.0-16.7 years) and 13.0 years (IQR 7.45-19.76 years), respectively (P < 0.001). Smoking, dyslipidemia, and arterial hypertension were associated less frequently with primary SS (odds ratio [OR] 0.36 [95% confidence interval (95% CI) 0.28-0.48], 0.74 [95% CI 0.58-0.94], and 0.50 [95% CI 0.38-0.66], respectively) as were life-threatening CV events (i.e., stroke or myocardial infarction; OR 0.57 [95% CI 0.35-0.92]). Conversely, lymphoma was associated more frequently with primary SS (OR 4.41 [95% CI 1.35-14.43]). The prevalence of severe infection was lower in primary SS than in SLE (10.1% versus 16.9%; OR 0.54 [95% CI 0.39-0.76]; P < 0.001).

Conclusion: Primary SS patients have a consistently less serious CV comorbidity burden and a lower prevalence of severe infection than those with SLE. In contrast, their risk of lymphoma is greater.