Background Mixed connective tissue disease (MCTD) and undifferentiated connective tissue disease (UCTD) are heterogeneous diseases which clinical manifestations are considerable overlapped with other connective tissue disease. Clinical diagnosis is usually depended on rheumatologists’ perception and experiences, though the classification criteria for each disease have been exist.
Objectives To evaluate agreement of expert opinion-based and classification criteria-based diagnosis in discriminating between MCTD and UCTD and impact of opinion-based diagnosis on the initial therapeutic pattern.
Methods Three hundred fifty six patients, who ever had ICD-10 code of M35.1 (other overlap syndrome) or M35.0 (systemic involvement of connective tissue, unspecified) during 2000-2011 were selected and retrospective chart review was performed. Among them, patients who had been confirmed as definite rheumatologic diseases within 3rd visit (n=185) or who had been diagnosed in other hospital (n=87) were excluded. New patients with MCTD (n=64) and with UCTD (n=20) were enrolled in this study. Agreement between opinion-based and criteria-based diagnosis were examined using Cohen’s Kappa. Initial clinical manifestation, autoantibody, and treatment pattern of opinion-based MCTD and UCTD were compared using the chi-squared test or Fisher’s exact test, as appropriated.
Results Agreement between opinion-based and criteria-based diagnosis was moderate (kappa, 0.59). When we discriminate between MCTD and UCTD according to expert opinion, high titer ANA (>1:2560) and the positivity of nRNP were distinct features of MCTD (P<0.05), though other clinical features were comparable. In the treatment, patients with MCTD were more often treated with prednisolone (P<0.05). The prevalence of treatment using combined regimen including immunosuppressant was high in MCTD patients even though it was not statistically significant.
Conclusions MCTD is often confused and is classified as UCTD in general practice and vice versa. The doctor’s initial perception for diagnosis in MCTD and UCTD influences on treatment pattern.
Disclosure of Interest None Declared
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