P331 Composite outcomes in Crohn’s disease: a systematic review and meta-analysis of observational studies

Estevinho, M.M.(1);Sottomayor, C.(2);Alves, C.(3);Santago, M.(4);Ministro, P.(5);Lago, P.(6);Correia, L.(7);Gonçalves, R.(8);Carvalho, D.(9);Portela, F.(10);Dias, C.C.(11);Dignass, A.(12);Danese, S.(13);Peyrin-Biroulet, L.(14);Magro, F.(15);

(1)Centro Hospitalar Vila Nova de Gaia/Espinho, Department of Gastroenterology, Vila Nova de Gaia, Portugal;(2)Unit of Pharmacology and Therapeutics- Faculty of Medicine- University of Porto, Department of Biomedicine-, Porto, Portugal;(3)Unit of Pharmacology and Therapeutics- Faculty of Medicine- University of Porto, Department of Biomedicine, Porto, Portugal;(4)Center for Health Technology and Services Research CINTESIS, Biomedicine, Porto, Portugal;(5)Centro Hospitalar Tondela-Viseu, Department of Gastroenterology, Viseu, Portugal;(6)Porto Hospital Center- Hospital de Santo António, Department of Gastroenterology, Porto, Portugal;(7)Lisbon North Hospital Centre- Santa Maria Hospital, Department of Gastroenterology, Lisbon, Portugal;(8)Hospital de Braga, Department of Gastroenterology, Braga, Portugal;(9)Santo António dos Capuchos Hospital at Centro Hospitalar Lisboa Central, Department of Gastroenterology, Lisbon, Portugal;(10)University Hospital Centre of Coimbra, Department of Gastroenterology, Coimbra, Portugal;(11)Information and Health Decision Sciences- Faculty of Medicine- University of Porto, Department of Community Medicine, Porto, Portugal;(12)Agaplesion Markus Hospital- Dept. of Medicine I, Gastroenterology, Frankfurt, Germany;(13)Humanitas Clinical and Research Center IRCCS, Inflammatory Bowel Disease IBD Center- Department of Gastroenterology-, Milan, Italy;(14)University Hospital of Nancy- University of Lorraine, Department of Gastroenterology and Inserm NGERE U1256-, Vandoeuvre-lès-Nancy, France;(15)São João University Hospital Center CHUSJ, epartment of Gastroenterology, Porto, Portugal; GEDII - Portuguese IBD Group


Observational studies are essential to analyse outcome reporting in inflammatory bowel disease. However, such studies are usually heterogeneous. Therefore, the development of core outcome sets to be included in future observational studies is of major importance. Composite and aggregate outcomes (in which an event is classified by the presence of any one or by the combination of every individual variable under assessment, respectively) allow maximizing the statistical power of observational studies. A systematic review and meta-analysis were performed to assess composite and aggregate outcomes in observational studies for Crohn’s disease (CD) and to evaluate whether the number and type of variables affect the frequency of the outcome.


Three online databases (PubMed, Scopus and Web of Science) were searched to identify observational studies that enrolled CD patients and evaluated a composite or aggregate outcome. The proportion of patients achieving the outcome was determined and a random-effects meta-analysis was performed to evaluate how the frequency of each outcome varied according to the reporting of predefined variables.


From the 10.257 identified records, 46 were included in the systematic review and 38 in the meta-analysis. The median frequency of composite and aggregate outcomes was 0.445 [95% confidence interval (CI) 0.389-0.501] and 0.140 [95% CI 0.000- 0.211], respectively. When comparing composite outcomes by the number of included variables, the frequency was 0.271 [95% CI 0.000- 0.405] and 0.698 [95% CI 0.651-0.746], for one and six variables, respectively. The frequency of the composite outcome varied according to the set of variables being reported. Specific pairs of predefined variables had a significant effect on the frequency of composite outcomes.


Composite outcomes with an increasing number of variables and those including the variables “surgery” and “steroids” presented higher frequencies. Moreover, specific variables and pairs of variables had a clear effect on the frequency of composite outcomes. Taking this information into account, future efforts must be made to standardize CD outcome reporting, a yet unmet need.