Problems with myocardial infarction definitions

To the Editor: In the December 2013 Cleveland Clinic Journal of Medicine, Tehrani and Seto provide a review of the updated definitions of myocardial infarction (MI).¹ A key concept incorporated into the structured definitions is that cardiac biomarkers must be interpreted in a clinical context.² This in turn helps better align the laboratory and clinical findings with the pathophysiologic processes.

However, there is another dimension to the definitions that is sometimes overlooked and requires careful attention: translation of the definitions into codes and comparable databases. Accurate and consistent coding according to the International Statistical Classification of Diseases, ninth edition (ICD-9), and the ICD-10 is critically vital to the appropriate analysis of data, research, quality measurement, and reimbursement of services related to MI. Unfortunately, there is no straightforward translation of the definitions into ICD-9 codes, and the challenge is further confounded when it comes to ICD-10, which will be implemented in October 2014.

The ICD-10-CM Index to Diseases does not yet recognize this nomenclature. ST-elevation MI is the default for the unspecified term “acute MI.” Non-ST-elevation MI requires more explicit documentation and is classified based on whether it occurs during or after a variety of procedures. Type 2 MI is particularly challenging because of the several possible ways to code the condition—for example, as acute subendocardial MI (I21.4), demand ischemia (I24.8), or acute MI, unspecified (I21.9). Coding guidelines are assumed to standardize the approach to coding these conditions, but there is no guarantee that comparability of the data will endure biases of code assignment. Although extreme precision in disease capture by coding may not exist, other clinical conditions have better correlations with coding classifications, such as stages of chronic kidney disease ranging from stage 1 through end-stage renal disease (N18.1 through N18.6). Furthermore, ICD-10 codes are insufficient to clearly distinguish the type of acute MI.³

While the concept of acute MI applies when the stated date of onset is less than 8 weeks in ICD-9,⁴ it changes to 4 weeks in ICD-10. “Acute” can reference an initial or a subsequent MI in ICD-10, but it does not define the time frame of the MI.⁵ This is different than in ICD-9, where the concept of “subsequent” refers to a “subsequent episode of care.”

On the surface, these variations may not seem significant. However, the discriminatory efforts to better define a patient’s clinical condition using the new definitions may get diluted by the challenges of the coding process. The implications on comparability of quality metrics and reporting are not to be underestimated and need to be assessed on a national level.

To the Editor: In the December 2013 Cleveland Clinic Journal of Medicine, Tehrani and Seto provide a review of the updated definitions of myocardial infarction (MI).¹ A key concept incorporated into the structured definitions is that cardiac biomarkers must be interpreted in a clinical context.² This in turn helps better align the laboratory and clinical findings with the pathophysiologic processes.

However, there is another dimension to the definitions that is sometimes overlooked and requires careful attention: translation of the definitions into codes and comparable databases. Accurate and consistent coding according to the International Statistical Classification of Diseases, ninth edition (ICD-9), and the ICD-10 is critically vital to the appropriate analysis of data, research, quality measurement, and reimbursement of services related to MI. Unfortunately, there is no straightforward translation of the definitions into ICD-9 codes, and the challenge is further confounded when it comes to ICD-10, which will be implemented in October 2014.

The ICD-10-CM Index to Diseases does not yet recognize this nomenclature. ST-elevation MI is the default for the unspecified term “acute MI.” Non-ST-elevation MI requires more explicit documentation and is classified based on whether it occurs during or after a variety of procedures. Type 2 MI is particularly challenging because of the several possible ways to code the condition—for example, as acute subendocardial MI (I21.4), demand ischemia (I24.8), or acute MI, unspecified (I21.9). Coding guidelines are assumed to standardize the approach to coding these conditions, but there is no guarantee that comparability of the data will endure biases of code assignment. Although extreme precision in disease capture by coding may not exist, other clinical conditions have better correlations with coding classifications, such as stages of chronic kidney disease ranging from stage 1 through end-stage renal disease (N18.1 through N18.6). Furthermore, ICD-10 codes are insufficient to clearly distinguish the type of acute MI.³

While the concept of acute MI applies when the stated date of onset is less than 8 weeks in ICD-9,⁴ it changes to 4 weeks in ICD-10. “Acute” can reference an initial or a subsequent MI in ICD-10, but it does not define the time frame of the MI.⁵ This is different than in ICD-9, where the concept of “subsequent” refers to a “subsequent episode of care.”

On the surface, these variations may not seem significant. However, the discriminatory efforts to better define a patient’s clinical condition using the new definitions may get diluted by the challenges of the coding process. The implications on comparability of quality metrics and reporting are not to be underestimated and need to be assessed on a national level.

To the Editor: In the December 2013 Cleveland Clinic Journal of Medicine, Tehrani and Seto provide a review of the updated definitions of myocardial infarction (MI).¹ A key concept incorporated into the structured definitions is that cardiac biomarkers must be interpreted in a clinical context.² This in turn helps better align the laboratory and clinical findings with the pathophysiologic processes.

However, there is another dimension to the definitions that is sometimes overlooked and requires careful attention: translation of the definitions into codes and comparable databases. Accurate and consistent coding according to the International Statistical Classification of Diseases, ninth edition (ICD-9), and the ICD-10 is critically vital to the appropriate analysis of data, research, quality measurement, and reimbursement of services related to MI. Unfortunately, there is no straightforward translation of the definitions into ICD-9 codes, and the challenge is further confounded when it comes to ICD-10, which will be implemented in October 2014.

The ICD-10-CM Index to Diseases does not yet recognize this nomenclature. ST-elevation MI is the default for the unspecified term “acute MI.” Non-ST-elevation MI requires more explicit documentation and is classified based on whether it occurs during or after a variety of procedures. Type 2 MI is particularly challenging because of the several possible ways to code the condition—for example, as acute subendocardial MI (I21.4), demand ischemia (I24.8), or acute MI, unspecified (I21.9). Coding guidelines are assumed to standardize the approach to coding these conditions, but there is no guarantee that comparability of the data will endure biases of code assignment. Although extreme precision in disease capture by coding may not exist, other clinical conditions have better correlations with coding classifications, such as stages of chronic kidney disease ranging from stage 1 through end-stage renal disease (N18.1 through N18.6). Furthermore, ICD-10 codes are insufficient to clearly distinguish the type of acute MI.³

While the concept of acute MI applies when the stated date of onset is less than 8 weeks in ICD-9,⁴ it changes to 4 weeks in ICD-10. “Acute” can reference an initial or a subsequent MI in ICD-10, but it does not define the time frame of the MI.⁵ This is different than in ICD-9, where the concept of “subsequent” refers to a “subsequent episode of care.”

On the surface, these variations may not seem significant. However, the discriminatory efforts to better define a patient’s clinical condition using the new definitions may get diluted by the challenges of the coding process. The implications on comparability of quality metrics and reporting are not to be underestimated and need to be assessed on a national level.