A Systematic Review of Crohn's Disease Case Definitions in Administrative or Claims Databases

Background: We sought to review Crohn's disease (CD) case definitions that use diagnosis, procedure, and medication claims.

Methods: We searched PubMed and Embase from inception through January 31, 2022, using terms related to CD, inflammatory bowel disease, administrative claims, or validity. Each article was scrutinized by 2 authors independently screening and abstracting data. Collected data included participant characteristics, case definition characteristics, and case definition validity. When diagnostic accuracy was provided for multiple case definitions, we extracted the case definition selected by the authors. All diagnostic accuracy characteristics were captured.

Results: We identified 30 studies that evaluated a case definition using claims data to identify CD patients. The most common case definition included counts of diagnosis codes (57%) followed by a combination of diagnosis codes and medications (20%). All but 1 study validated the case definition with a medical chart review. In 2 studies, the patient's primary care provider completed a survey to confirm disease status. The positive predictive value of the case definitions ranged from 18% (≥1 code at a single U.S. health plan) to 100% (≥1 code plus a relevant prescription at a U.S. hospital). More complex case definitions (eg, ≥1 code + prescription or ≥2 codes) had lower variability in positive predictive value (≥80%) and specificity (≥85%) than the ≥1 code requirement.

Conclusions: Health services researchers should validate case definitions in their research cohorts. When such validation cannot be performed, we recommend using a more complex case definition. Studies without a validated CD case definition should use sensitivity analyses to confirm the robustness of their results.