Development of a conceptual model evaluating the humanistic and economic burden of Crohn’s disease: implications for patient-reported outcomes measurement and economic evaluation

Abstract

The primary objective of this review is to develop a conceptual model for Crohn’s disease (CD) outlining the disease burden for patients, healthcare systems and wider society, as reported in the scientific literature. A search was conducted using MEDLINE, PsycINFO, EconLit, Health Economic Evaluation Database and Centre for Reviews and Dissemination databases. Patient-reported outcome (PRO) measures widely used in CD were reviewed according to the US FDA PRO Guidance for Industry. The resulting conceptual model highlights the characterization of CD by gastrointestinal disturbances, extra-intestinal and systemic symptoms. These symptoms impact physical functioning, ability to complete daily activities, emotional wellbeing, social functioning, sexual functioning and ability to work. Gaps in conceptual coverage and evidence of reliability and validity for some PRO measures were noted. Review findings also highlight the substantial direct and indirect costs associated with CD. Evidence from the literature confirms the substantial burden of CD to patients and wider society; however, future research is still needed to further understand burden from the perspective of patients and to accurately understand the economic burden of disease. Challenges with existing PRO measures also suggest the need for future research to refine or develop new measures.

Keywords:

• conceptual model
• costs
• Crohn’s disease
• health-related quality of life
• patient-reported outcome measures

Financial & competing interests disclosure

The study was funded by Novo Nordisk A/S, Denmark. A Gater, H Kitchen, L Heron, C Pollard are employees of Adelphi Values, a health outcomes agency acting as paid consultants to conduct the literature review on behalf of Novo Nordisk A/S. BB Hansen, L Højbjerre, J Håkan-Bloch and M Strandberg-Larsen are employees of Novo Nordisk A/S. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Crohn’s disease (CD) is a heterogeneous condition characterized by continuous relapses or ‘flares’ of gastrointestinal, extraintestinal and systemic symptoms, followed by periods of remission.

• Symptoms have a significant impact on patients’ lives (in terms of physical functioning, ability to complete daily activities, emotional well-being, social functioning, sexual functioning and ability to work).

• The heterogeneous and unpredictable nature of CD presents challenges for treatment as well as for understanding and measuring disease activity and impact. Research to date has rarely sought to explore the inter-relationships between concepts and the factors that may mediate or moderate these relationships (e.g., CD subtype or disease severity).

• Patient-reported outcome (PRO) measures are important for assessing the symptoms and impacts of CD. Findings from the current review, however, highlight issues with the validity of existing measures in the context of the FDA PRO Guidance (particularly whether these measures provide an adequate assessment of all symptoms of importance to patients). Future research may, therefore, be needed to refine or to support the development of new measures to accurately and reliably convey the patient experience.

• CD is associated with substantial direct and indirect costs that are highest among those patients with more severe disease symptoms or fistulas. However, the estimated costs for CD are, nevertheless, found to vary considerably across studies, likely due to differences in the underlying healthcare systems, methods of treating patients and study designs.

• A strong need, therefore, remains for additional studies to more accurately understand the impact of CD on society (in terms of direct and indirect costs).