Diagnostic Performance of Magnetic Resonance Enterography Disease Activity Indices Compared with a Histological Reference Standard for Adult Terminal Ileal Crohn’s Disease: Experience from the METRIC Trial
Authors: Kumar Shankar , Parry Thomas , Mallett Sue , Bhatnagar Gauraang , Plumb Andrew , Walsh Shaun , Scott Nigel , Tandon Ruchi , Chong Heung , du Parcq John , Martinez Adrianna , Moorghen Morgan , Rodriguez-Justo Manuel , Halligan Steve , Taylor Stuart A ,   METRIC study investigators, Baldwin-Cleland Rachel , Bloom Stuart , Gupta Arun , Hamlin Peter J , Hart Ailsa L , Higginson Antony , Jacobs Ilan , McCartney Sara , Miles Anne , Murray Charles D , Pollok Richard C , Punwani Shonit , Quinn Laura , Shabir Zainib , Slater Andrew , Tolan Damian , Travis Simon , Windsor Alastair , Wylie Peter , Zealley Ian , Dyer Jade , Veeramalla Pranitha , Tebbs Sue , Hibbert Steve , Ellis Richard , Thursby-Pelham Fergus , Beable Richard , Gibbons Nicola , Ward Claire , O’Connor Anthony , Lambie Hannah , Hyland Rachel , Lapham Roger , Quartey Doris , Scrimshaw Deborah , Bungay Helen , Betts Maggie , Fourie Simona , Power Niall , Ilangovan Rajapandian , Patel Uday , Mainta Evgenia , Lung Phillip , Johnston Ian , Naghibi Mani , Porte Francois , Alexakis Christopher , Pilcher James , Rahman Anisur , Vlahos Jonny , Greenhalgh Rebecca , Wale Anita , Beeston Teresita , Piga Wivijin , Clemente Joey , Rahman Farooq , de Caro Simona , Mehta Shameer , Vega Roser , Jastrub Roman , Sidhu Harbir , Rafiee Hameed , Tennent Mairead , Innes Caron , Mowat Craig , Duncan Gillian , Morris Steve 
Published: April 2022

Abstract

Background and Aims
The simplified magnetic resonance enterography [MRE] index of activity [sMARIA], London, and ‘extended’ London, scoring systems are widely used in Crohn’s disease [CD] to assess disease activity, although validation studies have usually been single-centre, retrospective, and/or used few readers. Here, we evaluated these MRE indices within a prospective, multicentre, multireader, diagnostic accuracy trial.

Methods
A subset of participants [newly diagnosed or suspected of relapse] recruited to the METRIC trial with available terminal ileal [TI] biopsies was included. Using pre-specified thresholds, the sensitivity and specificity of sMARIA, London, and ‘extended’ London scores for active and severe [sMARIA] TI CD were calculated using different thresholds for the histological activity index [HAI].

Results
We studied 111 patients [median age 29 years, interquartile range 21-41, 75 newly diagnosed, 36 suspected relapse] from seven centres, of whom 22 had no active TI CD [HAI = 0], 39 mild [HAI = 1], 13 moderate [HAI = 2], and 37 severe CD activity [HAI = 3]. In total, 26 radiologists prospectively scored MRE datasets as per their usual clinical practice. Sensitivity and specificity for active disease [HAI &gt;0] were 83% [95% confidence interval 74% to 90%] and 41% [23% to 61%] for sMARIA, 76% [67% to 84%] and 64% [43% to 80%] for the London score, and 81% [72% to 88%] and 41% [23% to 61%] for the ‘extended’ London score, respectively. The sMARIA had 84% [69-92%] sensitivity and 53% [41-64%] specificity for severe CD.

Conclusions
When tested at their proposed cut-offs in a real-world setting, sMARIA, London, and ‘extended’ London indices achieve high sensitivity for active TI disease against a histological reference standard, but specificity is low.