Abstract Background Crohn’s disease (CD) is an inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract. Although upper gastrointestinal (UGI) manifestations are better recognized in pediatrics, their frequency and clinical relevance in adults have historically been underestimated. Challenges include selective use of endoscopy, misattribution of UGI lesions to other conditions, and inconsistent application of classification systems. These limitations have led to highly variable prevalence estimates and hindered understanding of UGI disease in adult CD. We summarize the prevalence of UGI-CD in adult patients with CD, explore demographic variations in the presentation of UGI-CD, and summarize current knowledge gaps. Methods We conducted a scoping review of MEDLINE, Embase, and Cochrane CENTRAL (1995–Nov 2024) following JBI methodology and PRISMA-ScR guidance. Eligible studies reported adult UGI-CD prevalence or related epidemiological data. Extracted variables included study characteristics, prevalence estimates, site-level involvement, demographics, and disease behaviour. Systematic reviews were also included, providing pooled prevalence estimates and insights into ethnic variation, phenotype, and outcomes. Results A total of 115 primary studies and seven systematic reviews were included. Across 95 adult cohorts with extractable prevalence data, the median prevalence of UGI-CD was 9.1% (IQR 4.5–14.7%). Higher rates were consistently observed in cohorts using systematic endoscopy and biopsy at diagnosis regardless of symptomatology, while population-based and retrospective cohorts reported lower values. Isolated UGI-CD was rare, with a median prevalence of 1.37% (IQR 0.84–3.42%). Prevalence varied geographically and ethnically, with lowest rates in South Asian cohorts and higher rates in East Asian and Middle Eastern cohorts. Site-specific reporting (esophageal, gastric, duodenal, jejunal) was inconsistent, and few studies detailed modifiers such as smoking, family history, or extraintestinal manifestations. Conclusion Adult UGI-CD is more common than previously recognized, with a median prevalence of 9.1% (IQR 4.5–14.7%), but estimates remain highly variable due to inconsistent definitions and heterogeneous detection methods. To move the field forward, studies must adopt standardized, site-specific adult definitions and systematic diagnostic protocols, including clear guidance on when to perform endoscopy with biopsy, to generate accurate prevalence estimates and enable valid cross-study comparisons. Conflict of interest: Mr. Lupas, Daniel: No conflict of interest Natt, Navneet: No conflict of interest Elzaanoun, Reyad: No conflict of interest Yuan, Yuhong: No conflict of interest Mortuza, Rokhsana: No conflict of interest Ma, Christopher: Consulting fees: AbbVie, Alimentiv, Amgen, Anaptys Bio, AVIR Pharma Inc, Bristol Myers Squibb, Celltrion, Domain Therapeutics, Eupraxia, Eli Lilly, Ferring, Forte Biosciences, Fresenius Kabi, Gilead, Janssen, McKesson, Merck, Mirador Therapeutics, Pendopharm, Pfizer, Roche, Sanofi, Takeda, Tillotts Pharma Speaker’s fees: AbbVie, Amgen, AVIR Pharma Inc, Alimentiv, Bristol Myers Squibb, Eli Lilly, Ferring, Fresenius Kabi, Janssen, Merck, Organon, Pendopharm, Pfizer, Sanofi, Takeda, Tillotts Pharma Royalties: Springer Publishing Research Support: AbbVie, Eli Lilly, Ferring, Pfizer Vuyyuru, Sudheer: No conflict of interest Narula, Neeraj: Grant: Takeda, Pfizer, Abbvie Personal Fees: Abbvie, Janssen, Takeda, Pfizer, Merck, Amgen, Sandoz, Iterative Health, Innomar Strategies, Fresinius Kabi, Viatris, Celltrion, Organon, Eli Lilly, Ferring Non-financial Support: Abbvie, Janssen, Takeda, Pfizer, Ferring Crowley, Eileen: Grant: Research grant from Abbvie & Pfizer Personal Fees: Consulting fees from Alimentiv Inc. & Sanofi (Advisory board) Singh, Siddharth: Research grants from Pfizer Jairath, Vipul: Consulting Fees: Abbvie, Alimentiv, Amgen, Anaptys Bio, Asahi Kasei, Asieris, Astra Zeneca, Attovia, Blackbird Labs, BMS, Boehringer Ingleheim, Biomebank, Caldera, Calluna, Catalytic Health, Celltrion, Ensho, Enthera, Exeliome Biosciences, Ferring, Fresenius Kabi, Gilead, Granite Bio, GSK, Janssen, Lilly, Merck, Mountainfield, MRM Health, Nxera, Organon, OSE Immunotherapeutics, Pendopharm, Pioneering Medicine, Pfizer, Prometheus, Roche/Genentech, Sanofi, SCOPE, Shattuck Labs, Sorriso, Spyre, Synedgen, Takeda, Teva, Tillotts, Union Therapeutics, Ventus, Ventyx, Vividion, Xencor, Zealand Pharma. Sedano, Rocio: Has received consulting fees from AbbVie, Alimentiv, Pendopharm and Takeda.
Lupas et al. (Thu,) studied this question.