Systemic lupus erythematosus (SLe) gastrointestinal (Gi) complication is characterized by multisegment and multi-compartment involvement. The aim of this study is to develop a computed tomography (CT) image-based system for disease evaluation. SLE patients with GI involvement from two independent cohorts were retrospectively included. Baseline abdominal ct scan with intravenous and oral contrast was obtained from each individual. A CT scoring system incorporating the extent of GI tract involvement and intestinal wall thickness, along with extra-GI compartment involvement, was developed and validated. The outcome measurement was the time to GI functional recovery, defined as the time to tolerable per os (po) intake ≥50% of ideal calories (PO50). A total of 54 and 37 patients with SLE GI involvement were enrolled in the derivation and validation cohorts, respectively. The CT scores for SLE GI involvement were positively correlated with patients' time to PO50 (r = 0.57, p < 0.0001, derivation cohort; r = 0.42, p = 0.0093, validation cohort). Patients with a CT score ≤ 3 had a shorter time to PO50 (median time of 0 day) in pooled cohort, whereas those with a CT score > 3 incurred a significantly prolonged recovery with a median time to PO50 of 13 days (p < 0.0001). The CTbased scoring system may facilitate more accurate assessment and individualized management of SLE patients with Gi involvement. Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with multi-system involvement 1. Gastrointestinal (GI) manifestations are commonly presented in up to 50% of SLE patients 2 , with 2-30% of these cases attributed to active SLE per se 3 ; whereas others may due to treatment side effects or co-morbidities. Several key questions remain undetermined concerning active SLE GI involvement. First, multiplicity of its terminology, such as GI vasculitis (mesenteric vasculitis), lupus gastroenteritis (lupus enteritis) and intestinal pseudo-obstruction (IPO) 4-7 , implies the uncertainty of the underlying pathophysiology. Second, specific assessment tools for its activity, severity and outcome are lacking. As an example, none of the clinical features of SLE GI involvement is captured by the widely used SLE disease activity index (SLEDAI). It is noteworthy that computed tomography (CT) imaging has been well accepted in the evaluation of SLE GI involvement. Certain characteristic radiographic features 8,9 , such as 'target sign' (intestinal wall edema and thickening), 'comb sign' (enhanced engorgement of mesenteric vasculature), extra-GI compartment involvement (gallbladder wall thickening, interstitial cystitis, dilatation of urinary tract and biliary-pancreatic duct), have been described. However, image-based, prognosis-relevant measurable tools are yet to be developed. Third, the current treatment, particularly nutritional protocol for SLE patients with GI involvement, are merely empirical. Although the overall outcome is relatively benign 10 , some patients may suffer from a prolonged GI insufficiency, and some may...

Methods Patients with SLE gastrointestinal involvement from two independent retrospective cohorts were included in our study. All patients fulfilled the ACR 1997 revised classification criteria for SLE. CT scan at least once is necessary prior to glucocorticoid treatment in all enrolled patients. The primary endpoint was set to time to GI functional recovery, defined as intake 50% ideal calories POPO50. A new CT scoring system for SLE-VPO was established in the derivation cohort and validated in the validation cohort.