Validity of ICD-9-CM Coding for Identifying Incident Methicillin-Resistant Staphylococcus aureus (MRSA) Infections: Is MRSA Infection Coded as a Chronic Disease?

The Question

Medical investigators and decision-makers often rely on administrative codes to gauge infections rates and outcomes of methicillin-resistant Staphylococcus aureus (MRSA). One such database is the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). Is this method of assessment reliable?

What we found

49% of hospitalized patients in the study who were classified as infected with MRSA had no record of a MRSA infection during their hospital stay.  The agreement between MRSA classification and actual presence of MRSA infection had a ? coefficient of 0.26.

Why it matters

Based on the results of the study, the current ICD-9-CM is not a precise indicator of MRSA infection and should not be used to measure rates of MRSA infection.