Healthcare providers should plan for substantial disruption of billing and reimbursements upon switching to ICD-10 on Oct. 1, 2014, according to the results of an exhaustive study that attempted to map ICD-9 to ICD-10.

Providers in Europe and other regions that already have switched to ICD-10 reported “considerable disruption,” and according to a new study published in the Journal of the American Medical Informatics Association (JAMIA), providers in the United States will encounter a similar result.

ICD-9 does not map neatly into ICD-10, the study’s authors found. “Convoluted mappings indicate that multiple ICD-9-CM and ICD-10-CM codes share complex, entangled, and non-reciprocal mappings,” they wrote. After studying data from 24,008 patient visits in 217 emergency department, the researchers found that 36 percent of all diagnoses mappings were “convuluted.” Some areas, such as obstetrics and injuries, were convoluted in 60 percent of cases. According to the study:

From the proportion of convoluted mapping motifs, we determined that hematology and oncology are poised for easy transition, while obstetrics, psychiatry, and emergency medicine (poisoning) will be among the most challenged. Furthermore, 42% of infectious disease code mappings remain convoluted, which will impact most specialties. In addition, harder to transition ICD-10-CM to ICD-9-CM code ratios greater than five are found in musculoskeletal, injury, and poisoning clinical classes

“We establish that the meanings of a high proportion of the ICD-9-CM to ICD-10-CM mappings are entangled in complex mapping motifs that have the potential to induce inaccuracies and reporting errors,” they report. These convoluted codings represent 27 percent of treatment costs.

The solution? Double coding.

Because the relationship between ICD-9 and ICD-10 is not clean, coding staff will be challenged and automated coding tools will need to be replaced. “Memorized codes, training, and coding-support software need to start afresh,” the authors concluded.

The switch from ICD-9 to ICD-10 will be so complex that the authors recommend healthcare providers consider coding in both ICD-9 and ICD-10 in advance of the Oct. 1, 2014 deadline.

An alternative straightforward approach could be to conduct double coding (ICD-9-CM and ICD-10-CM) for the entangled ICD-9-CM codes and compare motifs in ICD-9-CM and ICD-10-CM in the final reports of the medical system or clinics, such as graph-pruning strategies to subsets offering reasonable coverage. However, dual coding is cost-prohibitive as coding to ICD-10-CM codes may require additional patient information that is available in patient charts but unobtainable from the historical ICD-9-CM claims. To mitigate the costs of double billing, we provide web portal tools, files, and charts to assess the risk profile per clinical condition, and to identify minimally affected ICD-9-CM codes.


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