Clinical Characteristics and Outcome of Primary Sjogren's Syndrome: A Large Asian Indian Cohort.

Objective: To characterise the clinical features, immunological profile and outcome in a cohort of Asian Indian patients with primary Sjögren's syndrome (SS).

Methods: Electronic medical records from a tertiary care teaching hospital in south India were screened for SS between 2004 and 2011. Patients fulfilling American European Consensus group (AECG) 2002 or American College of Rheumatology (ACR) 2012 classification criteria were included. Agglomerative hierarchical cluster analysis to identify patterns of associations between clinical and immunological features was done. Multivariate logistic regression to identify predictors of major systemic involvement was performed. Data on treatment and outcome were retrieved from electronic records.

Results: Of 423 patients suspected to have SS, 332 fulfilled inclusion criteria. Only 8.3% of patients complained of sicca symptoms on their own at initial presentation. Younger age of onset, higher female to male ratio, paucity of cryoglobulinemia, Raynaud's phenomenon and hyperglobulinemia were unique to this cohort. Cluster analysis revealed two subsets: The first cluster comprised of patients having a major systemic illness with high antibody titers and the second comprised of seronegative patients with mild disease. Over a third of SS cases had severe systemic manifestations necessitating treatment with immunosuppressants. In multivariate logistic regression analysis, anti-Ro and anti-La antibody positivity was associated with higher odds for systemic disease features (OR=2.67, P=0.03 and OR=3.25, P=0.003, respectively) whereas chronic pain was associated with lower odds (OR=0.4, p=0.032). Clinical improvement including symptomatic benefit in sicca and musculoskeletal features was noted with immunomodulators in the majority.

Conclusion: Our cohort of patients with SS has characteristic clinical features; some of them are in contrast with previous observations reported in European patients. This cohort consisted of two distinct patient clusters. The first cluster was associated with major systemic illness and high antibody titers, where as the second cluster comprised of seronegative patients with mild disease. Association of antibody positivity with systemic features was further confirmed on logistic regression analysis.