Abstract
Objective:This study examines the impact of the transition from ICD-9-CM to ICD-10-CM diagnosis coding on the recording of mental health disorders in electronic health records (EHRs) and claims data in ten large health systems. We present rates of these diagnoses across two years spanning the October 2015 transition.Methods:Mental health diagnoses were identified from claims and EHR data at ten health care systems in the Mental Health Research Network (MHRN). Corresponding ICD-9-CM and ICD-10-CM codes were compiled and monthly rates of people receiving these diagnoses were calculated for one year before and after the coding transition.Results:For seven of eight diagnostic categories, monthly rates were comparable during the year before and the year after the ICD-10-CM transition. In the remaining category, psychosis excluding schizophrenia spectrum disorders, aggregate monthly rates of decreased markedly with the ICD-10-CM transition, from 48 to 33 per 100,000. We propose that the change is due to features of General Equivalence Mappings (GEMS) embedded in the EHR.Conclusions:For most mental health conditions, the transition to ICD-10-CM appears to have had minimal impact. The decrease seen for psychosis diagnoses in these health systems is likely due to changes associated with EHR implementation of ICD-10-CM coding rather than an actual change in disease prevalence. It is important to consider the impact of the ICD-10-CM transition for all diagnostic criteria used in research studies, quality measurement, and financial analysis during this interval.
Highlights
The International Classification of Diseases Ninth Revision, Clinical Modification (ICD-9-CM) was developed for systematic study of illness, it is an essential component of the structured language of health care financing and evaluation of medical care
We examined several mental health disorder diagnosis groups, including depression, anxiety, attention deficit disorder, bipolar disorder, psychotic disorder, eating disorder and personality disorder, over a two-year period spanning the transition from ICD-9-CM to ICD-10-CM
Using medical records data from ten large health systems, we find that rates of many mental health diagnosis categories remained relatively stable or increased or declined gradually during the two years before and after the transition from ICD-9-CM to ICD-10-CM, and these trends were generally similar across the ten individual health systems
Summary
The International Classification of Diseases Ninth Revision, Clinical Modification (ICD-9-CM) was developed for systematic study of illness, it is an essential component of the structured language of health care financing and evaluation of medical care. Given the gradual adoption of EHR and the development of clinical terminology tools, these changes have had minimal disruption for the myriad uses of diagnosis data at the population level, and EHR data has been very beneficial for epidemiological research [3]. The recent adoption of International Classification of Diseases Tenth Revision, Clinical Modification (ICD10-CM) coding in the United States occurred nationwide on October 1, 2015. Major issues affecting health care operations were likely sorted out early in the ICD-10 era
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