JMIR Publications

ABSTRACT

Background:

Cross-institutional interoperability between healthcare providers remains a recurring challenge worldwide. The German Medical Informatics Initiative (MII), a collaboration of 37 university hospitals in Germany, aims to enable interoperability between partner sites by defining FHIR Profiles for the cross-institutional exchange of healthcare data, the Core Data Set (CDS). The current CDS and its extension modules define elements representing patients’ healthcare records. Over the last few years, all university hospitals in Germany have made significant progress in providing routine data in a standardized format based on the CDS. In addition, the central research platform for health, the “German Portal for Medical Research Data" (FDPG) feasibility tool, allows medical researchers to query the available CDS data items across many participating hospitals.

Objective:

This study aims to evaluate a novel approach of combining the current top-down generated FHIR profiles with bottom-up generated knowledge gained by analysis of respective instance data. This allows us to derive options for iteratively refining FHIR profiles utilizing the information obtained from a discrepancy analysis. For this, we investigate the CDS and its utilization at the clinical sites and in the FDPG feasibility portal.

Methods:

We developed a FHIR validation pipeline and opted to derive more restrictive profiles from the original CDS profiles. This decision was driven by the need to align more closely with the specific assumptions and requirements of the central feasibility platform's search ontology. While the original CDS profiles offer a generic framework adaptable for a broad spectrum of medical informatics use cases, they lack the specificity to model the nuanced criteria essential for medical researchers. A key example of this is the necessity to represent specific laboratory Codings and values interdependencies accurately. The validation results allow us to identify discrepancies between the instance data at the clinical sites and the profiles specified by the feasibility platform and addressed in the future.

Results:

A total of 20 university hospitals participated in this study. Historical factors, lack of harmonization, a wide range of source systems, and case sensitivity of Coding are some of the causes for the discrepancies identified. While in our case study, Conditions, Procedures, and Medications have a high degree of uniformity in the Coding of instance data due to legislative requirements for billing in Germany, we find that laboratory values pose a significant data harmonization challenge due to their interdependency between Coding and value.

Conclusions:

While the CDS achieves interoperability, different challenges for federated data access arise, requiring more specificity in the profiles to make assumptions on the instance data. We further argue that further harmonization of the instance data can significantly lower required retrospective harmonization efforts. We recognize that discrepancies cannot be resolved solely at the clinical site; therefore, our findings have a wide range of implications and will require action on multiple levels and by various stakeholders.