Variation of SNOMED CT coding of clinical research concepts among coding experts.

OBJECTIVE

To compare consistency of coding among professional SNOMED CT coders representing three commercial providers of coding services when coding clinical research concepts with SNOMED CT.

DESIGN

A sample of clinical research questions from case report forms (CRFs) generated by the NIH-funded Rare Disease Clinical Research Network (RDCRN) were sent to three coding companies with instructions to code the core concepts using SNOMED CT. The sample consisted of 319 question/answer pairs from 15 separate studies. The companies were asked to select SNOMED CT concepts (in any form, including post-coordinated) that capture the core concept(s) reflected in the question. Also, they were asked to state their level of certainty, as well as how precise they felt their coding was.

MEASUREMENTS

Basic frequencies were calculated to determine raw level agreement among the companies and other descriptive information. Krippendorff's alpha was used to determine a statistical measure of agreement among the coding companies for several measures (semantic, certainty, and precision).

RESULTS

No significant level of agreement among the experts was found.

CONCLUSION

There is little semantic agreement in coding of clinical research data items across coders from 3 professional coding services, even using a very liberal definition of agreement.