(322) US Claims Adaptation of the European Concerted Action on Congenital Anomalies and Twins (EUROCAT) Guide 1.5 for Use in Pregnancy Studies

Background: Observational safety studies in the post-authorization setting are used to evaluate the safety of newly approved drugs when used during pregnancy. Many of these studies focus on congenital malformations and rely on diagnosis codes found in U.S. claims data. While there is a lack of guidance for identifying and classifying malformations in claims data, resources for clinical assessment of malformations exist. One such resource is the European Concerted Action on Congenital Anomalies and Twins (EUROCAT) Guide which lists malformations as major or minor and provides the corresponding International Classification of Diseases 10th Revision (ICD-10) diagnosis codes with British Paediatric Association (BPA) extensions (ICD-10-BPA). However, this resource has not yet been formally adapted for use in U.S. claims where ICD-10-Clinical Modification (ICD-10-CM) codes are used.

Objectives: To translate the EUROCAT Guide 1.5 ICD-10-BPA classification of major and minor malformations into an ICD-10-CM code list for use in post-authorisation safety studies using U.S. administrative claims data.

Methods: Relevant sections of the ICD-10-CM 2022 database from the U.S. National Center for Health Statistics (NCHS) were downloaded for comparison to the EUROCAT ICD-10-BPA codes in Sections 3.2 and 3.3. When codes and descriptions matched, the ICD-10-CM codes were given the major/minor classification appearing in EUROCAT. For non-matching codes, manual review was conducted, and major/minor classification was based on matching descriptions. When major/minor classification could not be determined, a toggle variable was created to allow for study team discretion. In addition, disease categories were created to classify malformations by organ system. A team of n=11 scientists conducted a quality control investigation to ensure appropriate translation.

Results: A final code list was created, containing 916 ICD-10-CM codes: 744 major and 172 minor malformations. The code list is in Microsoft Excel and can be imported into statistical analysis applications such as SAS or R. It contains ICD-10-CM codes, their corresponding descriptions, their major or minor classification and disease category according to EUROCAT, and variables indicating anomalies caused by genetic or infectious diseases unlikely attributable to exposure to a study drug.

Conclusions: We adapted the EUROCAT Guide 1.5 into an ICD-10-CM code list for use in pregnancy studies using U.S. administrative claims data. This list has been updated to reflect new ICD-10-CM codes available in 2024. As new ICD-10-CM codes become available, or as the EUROCAT Guide is updated, further updates to this list will be needed.