Perianal fistulation is a challenging phenotype of Crohn's disease, with significant impact on quality of life. Historically, fistulae have been classified anatomically in relation to the sphincter complex, and management guidelines have been generalized, with lack of attention to the clinical heterogenicity seen. The recent 'TOpClass classification system' for perianal fistulizing Crohn's disease (PFCD) addresses this issue, and classifies patients into defined groups, which provide a focus for fistula management that aligns with disease characteristics and patient goals. In this article, we discuss the clinical applicability of the TOpClass model and provide direction on its use in clinical practice. An international group of perianal clinicians participated in an expert consensus to define how the TOpClass system can be incorporated into real-life practice. This included gastroenterologists, inflammatory bowel disease surgeons, and radiologists specialized in PFCD. The process was informed by the multi-disciplinary team management of 8 high-volume fistula centres in North America, Europe, and Australia. The process produced position statements to accompany the classification system and guide PFCD management. The statements range from the management of patients with quiescent perianal disease to those with severe PFCD requiring diverting-ostomy and/or proctectomy. The optimization of medical therapies, as well as the use of surgery, in fistula closure and symptom management is explored across each classification group. This article provides an overview of the system's use in clinical practice. It aims to enable clinicians to have a pragmatic and patient goal-centered approach to medical and surgical management options for individual patients with PFCD.

Background and aimObesity is a risk factor for both Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC). However, it is unclear whether obesity drives the malignant progression of BE. We aimed to assess whether obesity is associated with high-grade dysplasia (HGD) or cancer in patients with BE. MethodsWe searched MEDLINE and EMBASE from inception through April 2024 for studies reporting the effect of body mass index (BMI) on the progression of non-dysplastic BE or low-grade dysplasia (LGD) to HGD or EAC. A two-stage dose response meta-analysis was performed to estimate the dose-response relationship between BMI with malignant progression. Study quality was appraised using a modified Newcastle-Ottawa scale. The review was registered (PROSPERO ID CRD42017051046). ResultsTwenty studies reported data on 38565 patients (74.4% male) in total, of whom 1684 patients were diagnosed with HGD/cancer. Nineteen studies were considered moderate to high quality. Eight cohort studies reported data on 6647 male patients with baseline NDBE/LGD, of whom 555 progressed to HGD/EAC (pooled annual rate of progression 0.02%; 95% CI 0.01%-0.03%) and 1992 female patients with baseline NDBE/LGD with 110 progressors (pooled annual rate of progression 0.01%; 95% CI 0.01%-0.02%). There was no significant difference in pooled annual rate of progression between males and females (p=0.15). Each 5kg/m2 increase in BMI was associated with a 6% increase in the risk of malignant progression (adjusted OR 1.06; 95% CI 1.02-1.10; p<0.001; I2=0%). ConclusionOur meta-analysis provides some evidence that obesity as measured by BMI is associated with malignant progression of BE with a dose-response relationship. This finding requires confirmation in future high-quality cohort studies. Future risk prediction models could incorporate measures of obesity to potentially improve risk stratification in patients with BE.