ICD-10

Abstract: The validity of diagnostic definitions in psychiatry is directly related to the extent to which their etiology can be specified. However, since detailed knowledge of causal or susceptibility factors is lacking for most psychiatric disorders with a known or suspected familial-genetic origin, the current widely accepted classification systems largely fail to achieve this ideal. To illustrate this problem, this paper looks at the difficulties posed by the criteria for schizophrenia as laid down in the International Classification of Diseases, 10th revision (ICD-10) and the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R), and highlights the discrepancies between the majority of diagnostic boundaries and the various phenotype aggregation patterns observed in family studies. Progress in our understanding of psychiatric disorders requires to be firmly based on the findings of epidemiological studies as well as on a clear appreciation of the limitations of classification tools.

Abstract: The World Health Organization adopted the first version of the International Classification of Diseases (ICD) in 1900 to internationally monitor and compare mortality statistics and causes of death. Since then, the classification has been revised periodically to accommodate new knowledge of disease and health. The sixth revision, published in 1949, was more radical than the previous five revisions because this edition made it possible to record information from patient charts to compile morbidity statistics. Subsequent revisions were made in 1958 (7th Edition), in 1968 (8th Edition), and in 1979 (9th Edition). The United States modified ICD-9 by specifying many categories and extending coding rubrics to describe the clinical picture in more detail. These modifications resulted in the publication of ICD-9 Clinical Modification (ICD-9-CM) in 1979 for coding diagnoses in patient charts (Commission on Professional and Hospital Activities 1986). The latest version, ICD-10, was introduced in 1992 (World Health Organization 1992). The major differences between the ICD-10 and ICD-9-CM coding systems are: (1) the tabular list in ICD-10 has 21 categories of disease compared with 19 categories in ICD-9-CM and the category of diseases of the nervous system and sense organs in ICD-9-CM is divided into three categories in ICD-10, including diseases of the nervous system, diseases of the eye and adnexa, and diseases of the ear and mastoid process; and (2) the codes in ICD-10 are alphanumeric while codes in ICD-9-CM are numeric. Each code in ICD-10 starts with a letter (i.e., A–Z), followed by two numeric digits, a decimal, and a digit (e.g., acute bronchiolitis due to respiratory syncytial virus is J21.0). In contrast, codes in ICD-9-CM begin with three digit numbers (i.e., 001–999), that are followed by a decimal and up to two digits (e.g., acute bronchiolitis due to respiratory syncytial virus is 466.11). Canada, Australia, Germany, and other countries have enhanced ICD-10 by adding more specific codes and released country-specific ICD-10 versions, such as ICD-10-Canada (ICD-10-CA; Canadian Institute for Health Information 2003). However, ICD-10-CA has maintained its comparability with ICD-10. The basic ICD-10 structure, scope, content, and definition of existing codes are not altered in ICD-10-CA. This means that none of the ICD-10 codes are relocated or deleted. ICD-10-CA mainly extends code character levels, from third and fourth levels of ICD-10 to fourth, fifth, or sixth character levels (e.g., from I15.0 for renovascular hypertension to I15.00 for benign renovascular hypertension and I15.01 for malignant renovascular hypertension). A few additions of third- and fourth-level codes were also included in ICD-10-CA in a manner consistent with the existing classification. All of these additional codes are indicated with red maple leaf symbols in ICD-10-CA coding manuals. To continuously study the health care system and investigate or monitor population health status with ICD-10 data, it is imperative to assess errors that could occur in the process of creating administrative data due to the introduction of the new coding system, ICD-10. We conducted this study to evaluate the validity of ICD-10 administrative hospital discharge data and to determine whether there were improvements in the validity compared with the validity of ICD-9-CM data. To achieve this aim, we reviewed randomly selected charts coded using ICD-10 at four Canadian teaching hospitals, determined the presence or absence of recorded conditions, and then separately recoded the same charts using ICD-9-CM. Then we assessed the agreement between originally coded ICD-10 administrative and chart review data, and the recoded ICD-9-CM administrative data and chart review data for recording the same conditions. This permitted us to compare the accuracy of ICD-10 data relative to the chart review data, with the accuracy of ICD-9-CM data relative to the chart review data for these conditions.

Abstract: Background: The phecode system was built upon the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for phenome-wide association studies (PheWAS) using the electronic health record (EHR). Objective: The goal of this paper was to develop and perform an initial evaluation of maps from the International Classification of Diseases, 10th Revision (ICD-10) and the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) codes to phecodes. Methods: We mapped ICD-10 and ICD-10-CM codes to phecodes using a number of methods and resources, such as concept relationships and explicit mappings from the Centers for Medicare & Medicaid Services, the Unified Medical Language System, Observational Health Data Sciences and Informatics, Systematized Nomenclature of Medicine-Clinical Terms, and the National Library of Medicine. We assessed the coverage of the maps in two databases: Vanderbilt University Medical Center (VUMC) using ICD-10-CM and the UK Biobank (UKBB) using ICD-10. We assessed the fidelity of the ICD-10-CM map in comparison to the gold-standard ICD-9-CM phecode map by investigating phenotype reproducibility and conducting a PheWAS. Results: We mapped >75% of ICD-10 and ICD-10-CM codes to phecodes. Of the unique codes observed in the UKBB (ICD-10) and VUMC (ICD-10-CM) cohorts, >90% were mapped to phecodes. We observed 70-75% reproducibility for chronic diseases and <10% for an acute disease for phenotypes sourced from the ICD-10-CM phecode map. Using the ICD-9-CM and ICD-10-CM maps, we conducted a PheWAS with a Lipoprotein(a) genetic variant, rs10455872, which replicated two known genotype-phenotype associations with similar effect sizes: coronary atherosclerosis (ICD-9-CM: P<.001; odds ratio (OR) 1.60 [95% CI 1.43-1.80] vs ICD-10-CM: P<.001; OR 1.60 [95% CI 1.43-1.80]) and chronic ischemic heart disease (ICD-9-CM: P<.001; OR 1.56 [95% CI 1.35-1.79] vs ICD-10-CM: P<.001; OR 1.47 [95% CI 1.22-1.77]). Conclusions: This study introduces the beta versions of ICD-10 and ICD-10-CM to phecode maps that enable researchers to leverage accumulated ICD-10 and ICD-10-CM data for PheWAS in the EHR.