Comparability of probable and definite autoimmune hepatitis by international diagnostic scoring criteria.

BACKGROUND & AIMS: The diagnostic scoring systems for autoimmune hepatitis categorize some patients as having probable disease; this designation can affect treatment strategies and recruitment to clinical studies. A retrospective study was performed to determine the bases for the classification of probable autoimmune hepatitis and its clinical importance.
METHODS: The study included 185 adult patients who had been assessed at presentation for findings common to both international diagnostic scoring systems.
RESULTS: Seventeen patients (9%) were graded as probable autoimmune hepatitis by the revised original scoring system, and 28 patients (15%) were similarly designated by the simplified scoring system. These patients were distinguished from those designated as definite autoimmune hepatitis by male sex, concurrent immune diseases, lower serum γ-globulin and immunoglobulin G levels, and lower titers of autoantibody. Patients with definite or probable designations by either scoring system responded similarly to conventional corticosteroid regimens during comparable intervals of treatment. Full, partial, or nonresponses and treatment dependence were evident in all diagnostic categories with similar frequencies. Twenty-seven patients designated as probable autoimmune hepatitis by one system were designated as definite autoimmune hepatitis by the other system.
CONCLUSIONS: The designation of probable autoimmune hepatitis by the international scoring systems is based on differences in clinical manifestations and does not reflect differences in the validity of the diagnosis or its treatment response. Large multicenter prospective studies are necessary to establish these observations.