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

Lay Summary This systematic review of Crohn's disease (CD) case definitions identified that complex case definitions such as >= 1 diagnosis code + >= 1 prescription had desirable diagnostic accuracy properties. 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.

Automated summary

This systematic review examines case definitions of Crohn's disease and finds that more complex definitions involving multiple diagnostic codes and prescriptions have desirable diagnostic accuracy properties. The study suggests that health services researchers should validate case definitions in their cohorts and, if validation is not possible, use more complex definitions. Sensitivity analyses should be performed for studies without validated case definitions to confirm the robustness of their results.