Systematic Reviews
Copyright ©The Author(s) 2025. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Surg. Jul 27, 2025; 17(7): 101767
Published online Jul 27, 2025. doi: 10.4240/wjgs.v17.i7.101767
Epidemiology, treatment patterns, and associated risk factors in perianal fistulizing Crohn’s disease: A systematic literature review
Caroline McKay, Anna Bolzani, Scarlette Kienzle, Parnia Geransar, Julian Panés
Caroline McKay, Global Evidence & Outcomes, Takeda Pharmaceuticals USA, Inc., Cambridge, MA 02139, United States
Anna Bolzani, Scarlette Kienzle, Real World Evidence, Cytel Inc., Berlin 10785, Germany
Parnia Geransar, Global Medical Affairs – Rare GI, Takeda Pharmaceuticals International Co., Opfikon 8152, Zurich, Switzerland
Julian Panés, Department of Gastroenterology, Hospital Clínic de Barcelona, IDIBAPS, CIBERehd, Barcelona 08036, Spain
Author contributions: McKay C, Bolzani A, Kienzle S, Geransar P, and Panés J designed the overall concept of the work; Bolzani A, Kienzle S contributed to data acquisition and analysis; McKay C, Bolzani A, Kienzle S, Geransar P, and Panés J contributed to the interpretation of the data and the drafting of the manuscript.
Supported by Takeda Pharmaceuticals USA, Inc. Medical writing support was provided by Luke Humphreys, PhD, of Oxford PharmaGenesis, Oxford, UK and was funded by Takeda Development Center Americas, Inc.
Conflict-of-interest statement: McKay C was an employee of Takeda at the time of the study and is a shareholder in Merck and Johnson & Johnson. Bolzani A and Kienzle S are employees of Cytel. Cytel’s work was financially supported by Takeda Pharmaceuticals United States, Inc. Geransar P was an employee and shareholder of Takeda Pharmaceuticals at the time of the study. Panés J received consultancy fees/honorarium from AbbVie, Alimentiv, Athos, Atomwise, Boehringer Ingelheim, Celsius, Ferring, Galapagos, Genentech/Roche, GlaxoSmithKline, Janssen, Mirum, Nimbus, Pfizer, Progenity, Prometheus, Protagonist, Revolo, Sanofi, Sorriso, Surrozen, Takeda, and Wasserman and has served on a data safety monitoring board for Alimentiv, Mirum, Sorriso, Sanofi, and Surrozen.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Julian Panés, MD, Professor, Department of Gastroenterology, Hospital Clínic de Barcelona, IDIBAPS, CIBERehd, Carrer de Villarroel, 170, L'Eixample, Barcelona 08036, Spain. julian.panes@gmail.com
Received: September 25, 2024
Revised: April 7, 2025
Accepted: May 12, 2025
Published online: July 27, 2025
Processing time: 300 Days and 18.8 Hours
Abstract
BACKGROUND

Data regarding complex Crohn’s perianal fistulas (CPF) epidemiology are limited, and optimal treatment strategies are elusive. An improved understanding of how CPF treatment options are used in the real-world setting and factors associated with CPF development, treatment failure, and reasons for undergoing multiple surgeries may help to inform optimal patient management strategies, reduce treatment burden, and improve outcomes in patients with CPF.

AIM

To describe the epidemiology, treatments, outcomes, and associated risk/protective factors for complex CPF.

METHODS

Electronic databases (MEDLINE, EMBASE, EBM Reviews, EconLit) were searched. Two reviewers independently used populations, interventions, comparators, outcomes, study designs, and time criteria to identify relevant studies. Observational studies published in English from January 1, 2015 to February 17, 2022 with > 50 patients were included, even if complex CPF was not defined. Items of interest included complex CPF definitions, epidemiology, treatment patterns, morbidity, mortality, and risk factors associated with complex CPF development, treatment failure, and undergoing multiple surgeries. Data were reported using descriptive statistics.

RESULTS

Overall, 140 studies were included. Complex CPF definitions were heterogeneous and rarely reported (24 studies). Hence, data mostly related to CPF in general. CPF prevalence was variable (range: 1.5%-81.0%). Incidence was wide-ranging and mostly reported cumulatively at 1-year post-Crohn’s disease diagnosis (range: 3.5%-50.1%). Overall healing and failure rates after treatment were in the range of 10.5%-80.2% and 3.6%-83.0%, respectively. Abscesses were the most frequently reported morbidity (n = 18). No CPF-related deaths were reported. No consistent risk or protective factors were identified.

CONCLUSION

Epidemiology, treatment patterns, and risk factors for CPF vary, likely due to inconsistent CPF and clinical outcome definitions. Standardization would facilitate comparability, which may inform optimal complex CPF treatment strategies.

Keywords: Complex perianal fistula; Crohn’s disease; Epidemiology; Treatment patterns; Morbidity; Risk factors

Core Tip: This systematic literature review summarized data from recent studies reporting the epidemiology of Crohn’s perianal fistulas (CPF), treatment patterns, therapeutic response, morbidity, and mortality alongside risk/protective factors associated with CPF development, treatment failure, and reasons for undergoing multiple CPF-related surgeries. Substantial variability in outcomes was observed, indicating the need for standardized CPF study designs and consistent definitions for CPF and CPF-related clinical outcomes to achieve optimal treatment strategies and improved patient outcomes.