A Comparative Study of Mixed Connective Tissue Disease and Overlap Syndromes – A Single-Center Study from India

Abstract

Introduction: Mixed connective tissue disease (MCTD) a classical overlap syndrome with four different defining criteria. The present study attempts to compare the clinical features and autoantibodies for MCTD and overlap syndromes. Methods: In this observational study from October 2018 to August 2020, we included all the patients of MCTD and overlap syndromes. Alarcon–Segovia criteria was used as defining criteria for MCTD patients while the patients meeting diagnostic criteria for more than 1 of 6 classical autoimmune rheumatic diseases were selected in the overlap syndromes group. We compared their clinical features, laboratory parameters, and autoantibody profiles. MS Excel, STATA were used for statistical analysis, and comparison between the groups was done with t-test, Chi-square test, and Wilcoxon rank sum test. P < 0.05 was considered as statistically significant. Results: The study consisted of 60 consecutive patients (MCTD, n = 30 and overlap syndromes, n = 30) with higher female population in both groups (90% in MCTD and 84% in the overlap syndromes group) compared to males. The incidence of fever (83.3% vs. 46.6%), weight loss (60% vs. 26.6%), trigeminal neuralgia (76.6% vs. 13.3%), and myositis (63.3% vs. 20.0%) was significantly higher in MCTD than overlap syndromes whereas the incidence of cough (66.6% vs. 90.0%) and dry mouth (20.0% vs. 53.3%) was higher in overlap syndromes than MCTD (P < 0.05). Anti-U1 RNP antibodies were seen in all MCTD (100.0%) patients while anti-Scl 70 antibodies (60%) and anti-ribosomal-p-protein antibodies (13.3%) were seen in overlap syndromes. Conclusion: Fever and weight loss, trigeminal neuralgia, and myositis were more common in MCTD than overlap syndromes. Anti-U1 RNP antibodies seen in MCTD while Anti-Scl 70 antibodies and anti-ribosomal-P antibodies were commonly were seen in overlap syndromes.