Introduction and History of ICD Diagnosis Coding
The International Classification of Diseases (ICD) is the standard medical diagnostic tool that was initially developed by the World Health Organization for analyzing the constantly changing medical scenario around the world. The ICD contains a definite set of codes which has been revised and adopted as he HIPAA ICD-9 Clinical Modification coding system, known as ICD-9. Soon after the emergence, it has become the indispensable part of medical claims procedure. These codes are still very helpful to identify and describe the various medical conditions and spread of diseases and injury. Besides, it is also used to maintain vital records like birth and death certificates, health records for treatment and insurance.
In 1860, over a consensus to develop a model to collect hospital data, the International Classification of Causes of Death was developed. The World Health Organization (WHO) in 1948 took the reins of ICD and proposed to revise it every ten years. Nowadays, ICD-9-CM or the Ninth revision of ICD is primarily in use in the United States with target of revised ICD-10 standard code utilization from October 1, 2015. Only implemented in the United States, many other countries like Canada, Australia are already implementing ICD-10-AM as early as 1998.
Inside the ICD-9
The ICD-9 coding system contains three-to-five digit numeric codes, is an alphanumeric set where the first three digits represent the category. General diagnosis forms the category. The next fourth digit of numeric set is known as subcategory, closely followed by sub classification. Generally, the disease could be triggered by or followed by number of other medical conditions, this is described using subcategory. If the condition requires further explanation then it is described after a decimal point with another digit representing the cause or nature of the condition. There are three volumes that are studied in order to form an efficient ICD-9-CM code as part of the training.
Volume 1 contains 17 chapters describing various diseases, conditions and codes used to represent them. Volume 2 contains various diagnostic procedures used during treatment in alphabetical order linked back to diagnostic codes listed in Volume 1. Volume 3 contains procedural codes predominantly used by hospitals and other inpatient facilities for billing purposes.
Reading the ICD codes
As already discussed an ICD-9-CM code is formed of three to five digits representing the category, subcategory and sub classification to represent the patient medical information in standard code. More complex the diagnosis is, more digits are part of the diagnostic code.
We take example of a hand injury of a patient named Mrs. Smith. The patient reported to have slipped in her bathroom when she was filling in her laundry basket. She suffered feet injuries. Medical coder will use 825 as first three digit or category to represent the diagnosis made by the doctor of “fracture of one or more tarsal and metatarsal bones. The digit after the decimal stands for the subcategory. Since the patient suffered a close fracture, the coder should add 825.2 to specify it. If the fracture would have been open, the ICD-9 code would be 825.3
Let us draw a hierarchy here:
- Injury and poisoning (800-999)
- Fractures (800-829)
- Fractures of one or more tarsal and metatarsal bones (825)
- Multiple close and metatarsal bones (825.2)