Claims Data Fail to Accurately Identify MI Types

TOPLINE:

Clinical auditing reveals significant misclassification in administrative codes for myocardial infarction (MI), with only 39% of type 1 (T1MI) codes and 72% of type 2 (T2MI) codes for the condition accurately reflecting the true diagnosis, researchers found. Nearly half of patients coded for T1MI had T2MI, whereas 26% of T2MI codes represented myocardial injury.

METHODOLOGY:

• Researchers identified 350 randomly sampled patients with T1MI codes and 350 patients with T2MI codes during inpatient encounters using the International Statistical Classification of Diseases and Related Health Problems-10th Revision.
• The analysis included patients aged 65 years and older from October 1, 2017, to May 9, 2024, within eight hospitals in the Mass General Brigham system.
• Using the 4th Universal Definition of MI, the researchers reviewed the clinical encounters to assess evidence of plaque erosion or thrombus vs oxygen demand-supply imbalance.
• A second physician review was conducted for 146 challenging and 146 nonchallenging cases.

TAKEAWAY:

• Among the 350 patients coded as having had T1MI, clinical adjudication revealed 138 (39%) as correctly diagnosed; 159 (45%) in fact had T2MI, and 35 (10%) had myocardial injury.
• Of the 350 patients coded as having had T2MI, 251 (72%) were confirmed, four (1%) were found to have T1MI, and 91 (26%) had myocardial injury.
• A second physician review demonstrated a high degree of agreement with the initial review, with a 94% agreement in nonchallenging cases and 86% in challenging cases.
• Hospitals equipped with vs without cardiac catheterization laboratories showed significantly lower misclassification rates (43% vs 58%; P = .0298).

IN PRACTICE:

“Among individuals assigned a T1MI claims code, nearly one half have T2MI and many others have myocardial injury; fewer than one half have true T1MI,” the researchers reported. “Our results also confirm and extend previous work showing that among those with T2MI codes, slightly more than one half have true T2MI, with most of the misclassification related to myocardial injury rather than T1MI. This has critically important implications for epidemiology and public policy” related to acute myocardial infarction.

SOURCE:

The study was led by Andrea Martinez, MD, of the Department of Medicine at Massachusetts General Hospital, Boston. It was published online on July 21 in Journal of the American College of Cardiology.

LIMITATIONS:

The results may not be generalized to other hospital systems and countries, where patterns of misclassification might differ. The researchers noted external validity assessment across multiple healthcare systems and in countries that have already introduced International Classification of Diseases-11th revision coding would be beneficial. While patterns of misclassification might have changed over time, the analysis was intentionally restricted to the period when codes for both T1MI and T2MI were available.

DISCLOSURES:

The study received support through a grant to Jason Wasfy from the Massachusetts General Hospital Executive Committee on Research. Individual authors reported receiving other grants and support, including grants from industry.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.