The utility of the mHAI scoring system in pediatric autoimmune hepatitis diagnosis and its association with treatment response

Autoimmune hepatitis (AIH) is a chronic inflammatory autoimmune disease with either acute or chronic presentation. Previous scoring systems have primarily focused on chronic hepatitis, but none have been validated in an acute setting of pediatric patients. This study aimed to: 1) summarize the clinicopathologic characteristics of pediatric AIH patients; 2) assess if the modified Hepatic Activity Index (mHAI) can be used in both acute and chronic presentations of pediatric AIH; 3) evaluate the association of initial mHAI scores with treatment response at various endpoints. Thirty-one pediatric AIH patients were categorized into acute and chronic presentation groups. Biopsies were reviewed using the mHAI grading and staging system. AIH treatment endpoints were analyzed: 4 weeks (response vs. non-response), 6 months (complete vs. insufficient response), and approximately 12 months (histological remission vs. non-remission). Patients with acute AIH had higher mean mHAI scores and more prominent interface activity. Those achieving complete response at 6 months had significantly higher mean mHAI scores compared to those with an insufficient response. Notably, patients demonstrating fibrosis reversal at the 1-year follow-up often had higher initial mHAI scores. The mHAI can be used to evaluate acute and chronic presentations of pediatric AIH. Acute pediatric AIH has a higher mHAI score with more severe activity. The patients with a higher mHAI have a greater likelihood of achieving a complete response to treatment at 6 months and subsequent improvement in fibrosis status.