New ICD-10 coding system may cloud hospital safety

Andrew Boyd, Biomedical and Health Information Sciences

Andrew Boyd, assistant professor of biomedical and health information sciences. Photo: Roberta Dupuis-Devlin/UIC Photo Services

Changes in how medical diagnoses are coded under the latest international disease classification system – better known as the ICD-10 codes – may complicate the assessment of hospital safety, say researchers at the University of Illinois at Chicago.

Their report is available online in the Journal of the American Medical Informatics Association (JAMIA).

Codes for diagnoses that serve as patient safety indicators may not translate in a simple way from ICD-9 to ICD-10, says Andrew Boyd, assistant professor of biomedical and health information sciences at UIC and first author of the paper.

For example, a hemorrhage coded in ICD-9 may have any of several different codes in ICD-10 depending on which organ system is involved — making it difficult to tell whether a hospital’s safety record is improving, or information is simply slipping through the cracks.

“It’s possible to select ‘accurate’ new ICD-10 codes that make you look safer than you are because of the differences in the design of the ICD-10 system,” Boyd said. At the same time, he said, some hospitals may look less safe than they really are because of apparent increases in patient safety indicators that are actually the same indicators calculated differently.

Although hospitals may not deliberately try to game the system, the stakes are high — websites, including, and the U.S. News and World Reports’ hospital rankings use the patient safety indicators to give consumers information. Hospital reputations depend on these evaluations.

“People focus on these numbers because they are reported,” said Boyd.

The researchers looked at issues that could come up as hospitals change from one system to the other. Although some ICD-9 indicator codes might translate or “map” well, many more have very convoluted mappings, and some simply don’t map at all.

“There’s a lot of training going on all across the country about how these terms are best defined and coded, but we have 10,000 hospitals, thousands of coders and thousands of doctors,” Boyd said. “Is there a simple solution? Not so much.”

Boyd hopes that by highlighting where the difficulties lie, it will be possible to get beyond the numbers and use patient safety indicators as they were intended — as a way to improve procedures that impact patient safety.

Young Min Yang, Mike Burton and Bryan Becker of UIC; and Yves Lussier, Jianrong Li and Colleen Kenost, now at the University of Arizona, are co authors. All work was completed at UIC.

The study was supported grants from the Center for Clinical and Translational Sciences of the University of Illinois (NIH 1UL1RR029879-01, NIH/NCATS UL1TR000050), the UIC Institute for Translational Health Informatics, the Office of the Vice-President for Health Affairs of the University of Illinois Hospital & Health Sciences System, the Office of the Vice President for Health Sciences of the University of Arizona, the Arizona Health Sciences Center, the BIO5 Institute, the National Library of Medicine (K22LM008308-04), and the University of Arizona Cancer Center (P30CA023074).


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