"To be or not to be," ten years after: evidence for mixed connective tissue disease as a distinct entity.

Objectives: To determine if mixed connective tissue disease (MCTD) can be considered an independent clinical entity, to compare 3 different classification criteria for MCTD (Kasukawa, Alarcón-Segovia, and Sharp), and to define predictors (clinical features and autoantibodies) of potential evolution toward other connective tissue diseases (CTDs).

Methods: One hundred sixty-one MCTD patients were evaluated retrospectively at the diagnosis and in 2008. They were classified, at the diagnosis, according to the 3 classification criteria of MCTD (Sharp, Alarcón-Segovia, and Kasukawa) and reclassified in 2008 according to their evolution.