Incidence and Clinical Pattern of Mixed Connective Tissue Disease in Sudanese Patients at Omdurman Military Hospital: Hospital-Based Study

BACKGROUND: Mixed connective tissue disease (MCTD) is a rare autoimmune disease, characterized by the production of specific autoantibody anti-RNP, which presents with varied overlapping symptoms of different connective tissue disorders. The aim of this study is to identify the frequency and patterns of MCTD. METHODS: This is a descriptive cross-sectional hospital-based study conducted at the rheumatology clinic at Omdurman Military Hospital between February 2019 and July 2019. The study included 30 patients and data were collected using a designated questionnaire. RESULTS: The study showed that the majority of patients (96.7%) were females and only 3.3% was male. About 30% of the patients aged between 30 and 39 years were the most affected. As a first diagnosis, 10% of the patients had a MCTD fulfilling the Alarcon-Segovia criteria. The remaining 90% of the patients were diagnosed with other diseases before evolving into MCTD. The most common clinical presentation was arthralgia in 100% of the patients, 90% were symmetrically followed by myositis in 70% of the patients, arthritis in 63.3% of the patients, puffy fingers in 63.3% of the patients, and hand swelling in 60% as major musculoskeletal symptoms. Regarding the initial results in immunological profile, the most common positive autoantibodies among the patients were anti-RNP titer in 96.7% of the patients, ANA in 90%, anti-Sm in 50%, RF in 50%, anti-Ds DNA in 46.7%, and anti-Ro in 43.3%. CONCLUSION: This study showed that MCTD is more common in females, only 10% of patients presented with a fulfilling criteria of the disease at diagnosis, and the rest of the patients presented with other rheumatologic diseases before evolving into MCTD.