ICD Does Not Identify Acute Optic Neuritis

Acute optic neuritis (ON) identification using International Classification of Diseases (ICD) codes plus a magnetic resonance imaging (MRI) examination within 2 months initial ICD coding has low accuracy, according to research published in the Journal of Neuro-Ophthalmology.

Researchers conducted a retrospective chart review to determine the accuracy for ICD code for acute optic neuritis plus MRI within 2 months regardless of results. They used patient data from 1998 to 2019 in a medical record research repository of a tertiary care institution. Patients with ICD-9/10 codes for ON and a report for MRI of the brain and/or orbits within 2 months of the initial ICD code were included in the analysis.

At the time of the initial ICD code, clinical diagnosis was classified as acute ON, prior ON, considered ON, alternative diagnosis, or unknown. The team calculated the accuracy of ICD code for acute optic neuritis, acute or prior optic neuritis, and acute, prior, or considered ON for all patients and stratified based on MRI result.

A total of 251 patients had MRI results within 2 months of their initial ICD code for ON (49 with positive MRI; 202 with negative MRI). Among those with a negative MRI result, 16% had acute optic neuritis, 20% had prior ON, 9% had considered ON as a diagnosis, 46% had other confirmed diagnoses, and 9% had unknown diagnosis at the time of initial ICD code. 

The researchers estimate the accuracy for ICD code is 25% for acute ON, 41% for acute or prior optic neuritis, and 48% for acute, prior, or considered ON. The 25% accuracy “further decreases to 16% if limited to negative MRIs and increases to 61% with positive MRIs,” they explain. “This suggests that MRI results are useful for identifying acute ON cases based on ICD codes. However, although performance of an MRI can be assessed from medical claims data, the result cannot. Therefore, we assessed other parameters and found none that improved identification accuracy above 70% and all of which compromised the sample size.”

“Ultimately our results suggest that optic neuritis cases cannot be accurately identified by ICD and MRI completion alone and that clinical record review is required,” according to the researchers.

Limitations of the study included the retrospective, single-center design and limited sample size.