Electronic Thesis and Dissertation Repository


Master of Science


Epidemiology and Biostatistics


Dr. Guangyong Zou

2nd Supervisor

Dr. Brian Feagan

Joint Supervisor


Background and Objective: Crohn’s disease (CD)-related complications account for a substantial proportion of IBD-related healthcare expenditure. Identifying patients at risk for complications may allow for targeted use of early therapeutic interventions to alter this natural course. The objective of this project was to develop risk prediction models of CD-related surgery and complications.

Methods: Using data from the REACT cluster-randomized clinical trial (N=1898 from 41 community practices), prediction models were developed and internally validated for CD-related surgery and CD-related complications, defined as the first CD-related surgery, hospitalization or complication within 24 months. Performance of each model was assessed in terms of discrimination and calibration, as well as decision curves and net benefit analyses.

Results: There were 130 (6.8%) CD-related surgeries and 504 (26.6%) CD-related complications during the 24-month follow-up period. Selected baseline predictors for predicting surgery included age, gender, disease location, HBI score, stool frequency, antimetabolite or 5-aminosalicylates use, and the presence of a fistula, abscess or abdominal mass. Selected predictors of complications included those same factors for surgery, corticosteroid and TNF-antagonist use and excluded 5-aminosalicylate use. The discrimination ability, as measured by optimism-corrected c-statistic, was 0.70 for the surgery model, and 0.62 for the complication model. Score charts and nomograms were developed to facilitate future risk score calculation.

Conclusions: Risk prediction models for CD-related surgery and CD-related complications were developed using clinical trial data involving community gastroenterology practices. These models need to be externally validated before being used to guide management of CD.