Crohn’s disease (CD) and ulcerative colitis (UC) are chronic, inflammatory bowel diseases (IBDs) of unknown origin, affecting the gastrointestinal tract and often causing extraintestinal symptoms. Conventional treatments (eg, glucocorticosteroids, immunomodulators) and targeted advanced treatments, including anti-TNFα, antibodies to p40 subunit of IL-12/23, antibodies to p19 subunit of IL-23, anti-α4β7 integrin, Janus kinase inhibitors (JAKis) and sphingosine-1-phosphate receptor (S1PR) modulators, do not achieve sustained responses for all patients, leaving significant unmet therapeutic needs.

This prospective, multi-centre observational study will follow a cohort of 240 patients across multiple study centres within NHS trusts in the UK who are initiating or switching biologics, specifically anti-TNFα and anti-α4β7 integrin for UC, and anti-TNFα, antibodies to p40 subunit of IL-12/2 and JAKi for CD. Through comprehensive profiling of immunological, transcriptional, microbiome, genetic and proteomic markers at baseline, week 12, and week 52, this study aims to uncover non-invasive biomarkers that predict response to these drug classes, ultimately advancing personalised medicine in IBD.

Ethical approval for the Nottingham/AstraZeneca study was granted by the West of Scotland Research Ethics Committee. Recruitment began in December 2022 and is currently ongoing at 10 NHS Trust sites across the UK. Study findings will be disseminated by publication in peer-reviewed journals and presentations at relevant national and international conferences.

To examine the longitudinal impact of time-varying factors on US youth’s trajectories of initiation and use of e-cigarettes and cigarettes during the transition from adolescence to young adulthood.

Longitudinal.

Nationally representative US survey, the Population Assessment of Tobacco and Health (PATH) Study.

2682 US youth (aged 16–17) at wave (W)1 of the PATH Study across six waves (2013–2020) into young adulthood (aged 22–23).

Unweighted longitudinal latent class analyses identified trajectory classes of e-cigarette and cigarette use, separately. Nationally representative weighted multinomial logistic regression analyses examined time-varying harm perceptions, substance use problems and tobacco product first tried as predictors of these trajectory classes.

Five e-cigarette classes (2013–2020; 41.5% Persistent Never Use, 12.6% W5 Initiation, 19.9% W3 Initiation, 15.2% Prior Initiation, 10.8% High Frequency Past 30-Day (P30D) Use) and five cigarette classes (2013–2019; 58.6% Persistent Never Use, 11.5% W4 Initiation, 10.9% W2 Initiation, 9.6% Prior Initiation, 9.5% High Frequency P30D Use) were identified. Time-varying harm perceptions and substance use problems were associated with trajectories of initiation and use for both products. Cigarettes, cigarillos, other combustibles and any smokeless tobacco as first product tried were associated with e-cigarette initiation and/or progression to high frequency use. E-cigarettes and hookah as first product tried were associated with later cigarette initiation. High Frequency P30D Cigarette Use was less likely if the first product tried was e-cigarettes, cigarillos, hookah or any smokeless tobacco product.

Results reinforce the need for identification and intervention of early substance use among younger adolescents and targeted public health messaging to address changing harm perceptions and prevent initiation among older adolescents.