Background and Aims: The incidence of inflammatory bowel diseases [IBD] has risen over the past decade to become a global issue. The objectives of this review were to describe the incidence and/or prevalence of IBD in the era of advanced therapies, and to describe the association between environmental risk factors and both pathogenesis and disease course across the ages. Methods: We performed a search of English language publications listed in PubMed regarding the epidemiology of IBD and key environmental factors implicated in IBD from January 2000 to December 2023. Results: Annual incidence rates varied by geographical region with IBD estimates ranging from 10.5 to 46.14 per 100 000 in Europe, 1.37 to 1.5 per 100 000 in Asia and the Middle East, 23.67 to 39.8 per 100 000 in Oceania, 0.21 to 3.67 per 100 000 in South America, and 7.3 to 30.2 per 100 000 in North America. The burden of IBD among children and adolescents, and older people is rising globally. Key environmental factors implicated in IBD pathogenesis include exposure to tobacco smoking, antibiotics, non-steroidal anti-inflammatory drugs, oral contraceptives, infections, and ultra-high processed foods. Breastfeeding and a high-quality diet rich in fruit, vegetables, fish, and other fibre sources are important protective factors. Smoking has consistently been shown to negatively impact disease outcomes for Crohn’s disease. Conclusion: The epidemiology of IBD has undergone considerable change in recent decades, with an increase in the burden of disease worldwide. Optimally studying and targeting environmental triggers in IBD may offer future opportunities for disease modification.

Inflammatory bowel disease (IBD) commonly requires immunosuppressive treatments to induce and maintain durable remission. Janus kinase inhibitors (JAKis) are a novel group of orally administered, small molecule drugs that work by attenuating multiple cytokine signalling pathways to mediate dysregulated immune responses involved in the pathogenesis of IBD. Tofacitinib, filgotinib and upadacitinib have demonstrated efficacy against placebo and are licensed for the treatment of moderate to severe ulcerative colitis; upadacitinib is the only JAKi also currently approved for the treatment of Crohn’s disease. Safety concerns stratified by age have led to class-wide regulatory restrictions for JAKi use across all inflammatory diseases. It is important for gastroenterologists managing patients with IBD to be aware of the key pivotal trial outcomes, to identify appropriate patients in whom to commence a JAKi, and to understand the safety considerations and ways to mitigate these risks in the patients they treat. This review provides a contemporaneous overview of this emerging therapeutic class and provides a practical guide for healthcare practitioners for initiating and monitoring JAKi in IBD.

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn’s disease (CD), is a costly condition in terms of morbidity and healthcare utilization, with an increasing prevalence now approaching 1% in the Western world. Endoscopic assessment of IBD remains the gold standard for diagnosis, evaluation of treatment response and determination of post-operative recurrence, but is expensive and invasive. Biomarkers can facilitate non-invasive disease assessment, with C-reactive protein and faecal calprotectin as the most widely available biomarkers in current clinical practice. This narrative review summarizes the evidence for their use in both UC and CD and offers practical guidance for healthcare providers taking into account the limitations of biomarker interpretation. We present evidence for the future use of novel biomarkers in IBD and discuss how biomarker discovery could deliver the goal of precision medicine in IBD.

Acute severe ulcerative colitis (ASUC), characterised by bloody diarrhoea and systemic inflammation, is associated with a significant risk of colectomy and a small risk of mortality. The landmark trial of cortisone in 1955 was pivotal for two reasons: first, for establishing the efficacy of a drug that remains a first-line therapy today and, second, for producing the first set of disease severity criteria and clinical trial endpoints that shaped the subsequent ASUC trial landscape. Trials in the 1990s and at the turn of the millennium established the efficacy of infliximab and ciclosporin, but since then, there has been little progress in drug development for this high-risk population. This systematic review evaluates all interventional randomised controlled trials (RCTs) conducted in patients hospitalised with severe UC. It provides an overview of the efficacy of treatments from past to present and assesses the evolution of trial characteristics with respect to study populations, eligibility criteria and study designs over time. This review details ongoing RCTs in this field and provides a perspective on the challenges for future clinical trial programmes and how these can be overcome to help deliver novel ASUC therapies.