PEMPAC

PEMPAC (Pediatric magnetic resonance imaging [MRI]-based perianal Crohn's disease) index ^1-2

Aim: To evaluate and score the severity of perianal disease in children with Crohn’s disease using pelvic MRI.

The PEMPAC index incorporates key radiological parameters, including the number, location, and length of fistulas, T2 hyperintensity, and the presence of abscesses. It accurately differentiates perianal remission from active disease, achieving an area under the receiver operating characteristic curve (AUC) of 0.91 (95%CI: 0.86–0.97) to 0.94 (95%CI: 0.89–0.98). The index also demonstrates strong responsiveness to longitudinal changes, with an AUC of 0.89 (95%CI: 0.69–1.00).

Clinical Application & Cutoffs:

• Radiological Remission: A PEMPAC score of <10 on pelvic MRI is established as the formal cutoff for radiological remission.

• Prognostic Value: Multicenter evidence from the Pediatric IBD Porto Group of ESPGHAN demonstrates that baseline PEMPAC scores independently predict therapeutic response, with lower baseline scores associated with significantly higher rates of clinical and radiological remission on biologic therapy.