ICD – International Classification of Diseases
The International Classification of Diseases (ICD) is designed for the classification of Morbidity and Mortality information for statistical purposes, and for the indexing of hospital records by disease and operations, for data storage and retrieval. Most providers are have historically been and are currently working with the 9th edition (revision) of the ICD codes. However, a 10th revision is on its way. What is it? Don’t be fooled by programs which promise to train on ICD-10. The Centers for Medicare and Medicaid Services (CMS) announced in January 2009 that ICD-10-CM will be implemented into the HIPAA mandated code set on Oct. 1, 2013. In the meantime, coders MUST know ICD-9, which is what Meditec trains students on.
Where did it come from?
ICD is published by the World Health Organization (WHO). Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copyright Convention. For rights of reproduction or translation of WHO publications, in part or in toto, application should be made to the Office of Publications, World Health Organization, Geneva, Switzerland. The World Health Organization welcomes such applications.
A classification of diseases may be defined as a system of categories to which morbid entities are assigned according to some established criteria. There are many possible choices for these criteria. The anatomist, for example, may desire a classification based on the part of the body affected whereas the pathologist is primarily interested in the nature of the disease process, the public health practitioner in etiology and the clinician in the particular manifestation requiring his care. In other words there are many axes of classification and the particular axis selected will be determined by the interest of the investigator. A statistical classification of disease and injury will depend, therefore, upon the use to be made of the statistics to be compiled. Because of this conflict of interests, efforts to base a statistical classification a strictly logical adherence to any one axis have failed in the past. The various titles will represent a series of necessary compromises between classifications based on etiology, anatomical site, circumstances of onset, etc., as well as the quality of information available on medical reports. Adjustments must also be made to meet the varied requirements of vital statistics offices, hospitals of different types, medical services of the armed forces, social insurance organizations, sickness surveys, and numerous other agencies. While no single classification will fit all the specialized needs, it should provide a common basis of classification for general statistical use; that is storage, retrieval and tabulation of data.
The traditional ICD structure has been retained but an alphanumeric coding scheme replaces the previous numeric one. This provides a larger coding frame and leaves room for future revision without disruption of the numbering system, as has occurred at previous revisions. In order to make optimum use of the available space, certain disorders of the immune mechanism are included with diseases of the blood and blood-forming organs (Chapter III). New chapters have been created for diseases of the eye and adnexa and diseases of the ear and mastoid process. The former supplementary classifications of external causes and of factors influencing health status and contact with health services now form part of the main classification. The dagger and asterisk system of dual classification for certain diagnostic statements, introduced in the Ninth Revision, has been retained and extended, with the asterisk axis being contained in homogeneous categories. The “dagger and asterisk” system in ICD-10 ICD-9 introduced a system, continued in ICD-10, whereby there are two codes for diagnostic statements containing information about both an underlying generalized disease and a manifestation in a particular organ or site which is a clinical problem in its own right. The primary code is for the underlying disease and is marked with a dagger (+); an optional additional code for the manifestation is marked with an asterisk (*). This convention was provided because coding to underlying disease alone was often unsatisfactory for compiling statistics relating to particular specialties, where there was a desire to see the condition classified to the relevant chapter for the manifestation when it was the reason for medical care. While the dagger and asterisk system provides alternative classifications for the presentation of statistics, it is a principle of the ICD that the dagger code is the primary code and must always be used. Provision should be made for the asterisk code to be used in addition if the alternative method of presentation may also be required. For coding, the asterisk code must never be used alone. Statistics incorporating the dagger codes conform with the traditional classification for presenting data on mortality and morbidity and other aspects of medical care. Asterisk codes appear as three-character categories. There are separate categories for the same conditions occurring when a particular disease is not specified as the underlying cause. For example, categories G20 and G21 are for forms of Parkinsonism that are not manifestations of other diseases assigned elsewhere, while category G22* is for “Parkinsonism in diseases classified elsewhere”. Corresponding dagger codes are given for conditions mentioned in asterisk categories; for example, for Syphilitic parkinsonism in G22*, the dagger code is A52.1+. Some dagger codes appear in special dagger categories. More often, however, the dagger code for dual-element diagnoses and unmarked codes for single-element conditions may be derived from the same category or subcategory. The areas of the classification where the dagger and asterisk system operates are limited; there are 83 special asterisk categories throughout the classification, which are listed at the start of the relevant chapters. Rubrics in which dagger-marked terms appear may take one of three different forms: If the symbol (+) and the alternative asterisk code both appear in the rubric heading, all terms classifiable to that rubric are subject to dual classification and all have the same alternative code, e.g.
A17.0+ Tuberculous meningitis (GO1*)
- Tuberculosis of meninges (cerebral) (spinal)
- Tuberculous leptomeningitis
A18.1+ Tuberculosis of genitourinary system
- Bladder (N22.0*)
- Cervix (N74.0*)
- Kidney (N29.1*)
- Male genital organs (N51.-*)
- Ureter (N29.1*)
So, coding a tuberculosis of the bladder would use these 2 codes: A18.1+ and N22.0* >