If we define medical coding as the assignment of alphanumerical characters to diagnoses, diseases, and treatments, then medical coding has been traced back to the 1600s in England with the London Bills of Mortality. A more standardized system of coding was developed for classifying death at the tail end of the 19th century. In 1893, Jacque Bertillon, a statistician, created the Bertillon Classification of Causes of Death, a system which was eventually adopted by 26 countries at the beginning of the 20th century. Shortly after the Bertillon Classification system was implemented, people began discussing the possibility of expanding the system beyond mortality as a way of tracking diseases.
By the middle of the 20th century, the World Health Organization (WHO) adopted a goal of a single global classification system for disease and mortality, entitled the International Classification of Diseases, Injuries, and Causes of Death (ICD). This classification system is updated every 10 years. The latest revision, ICD-10, is scheduled for adoption in the United States in 2013.
What started out as a small set of medical codes has evolved into a complex system that was initially standardized by the American Medical Association back in 1966 with current procedure codes (CPT) codes that are updated annually.
In the late 1970s, the Healthcare Common Procedure Coding System (HCPCS) was developed based on CPT. HCPCS has three levels of codes: Level One is the original CPT system. Level Two codes are alphanumeric and include non-physician services such as ambulances and other transportation as well as patient devices such as prosthetic devices. Level Three codes were developed as local codes, and were discontinued in 2003 in order to keep all codes relevant worldwide.
Recently, medical coding systems have been expanded to include other medical specialties. For example, there are coding systems related to disabilities, the dental field, prescription drugs, and mental health.
As the coding systems have become more complex and diverse, the need for training of medical coders has grown exponentially. Private training schools and public colleges throughout the country have developed certification programs. In order to be awarded a certificate, students must obtain a two-year degree from an accredited medical coding school and pass an exam given by the AHIMA.
Over the past 20 years, many coding processes have shifted from a paper-based system to a computer-based system using medical coding software and medical billing software. Many companies sell complete medical software-based coding solutions and myriad of products for specific medical disciplines, such as products that are specifically tailored to skilled nursing facilities, physicians, hospitals, surgery, cardiology, and more.
As medical facilities and professionals begin preparing for the conversion to ICD-10 in 2013, the need for more sophisticated medical coding software solutions and qualified medical coders will continue to grow.
CPT is a registered trademark of the American Medical Association.