ICD, DRG, CPT ... What are they all for?

With the number of codification systems used in healthcare it can be hard to keep track of what they are all for. ICD, DRG, CMG, CCI, CPT ....

ICD, DRG, CPT ... What are they all for?

Both the technology and healthcare industries are hard at work to improve interoperability. At the patient level, the goal is to enable meaningful information exchange. While at the same time increasing a patient’s access to their clinical and billing information. On a global scale, there is a desire to aggregate and analyze healthcare data to assist with improving care outcomes. This data will drive development in personalized care and artificial intelligence. It will also play a vital role in healthcare cost management. A key component for each of these is the underlying code systems that we use. The use of healthcare code systems in North America is quite complex. With so many acronyms out there, it can get confusing. Over the next while, I thought I’d try to briefly summarize a few of them…. so let's jump right in with some of the bigger ones used in the US and Canada.

International Classification of Diseases (ICD)

The origins of this classification system date back to the 1890s with the International List of Causes of Death. Well over a century later, the code set has gone through several version upgrades. It has been translated into 43 languages and is being used by more than 100 countries. The World Health Organization (WHO) currently develops and maintains the list for use by Member States. The classification system is for reporting and monitoring diseases and health conditions. The code set is also used by many for information exchange, research, and healthcare billing.

Over the last several years there was a lot of media coverage about version 10 of ICD. This version was endorsed by the World Health Assembly in May of 1990 but was only implemented in the US on Oct 1, 2015. (Canada approved a version for implementation in 1995.) To understand the delays, it is important to mention that ICD does not include a procedure classification system. Each Member State country that tracks procedures needs to develop clinical modifications to the code set before implementing it. This development can be complex and may take significant time to complete.

In the US there are two modifications to the main ICD code set. The first is ICD-10 Clinical Modification (ICD-10 CM) maintained by the National Center for Health Statistics (NCHS). Healthcare organizations use ICD-10 CM for the reporting of diagnosis. The second modification is ICD-10 Procedure Classification System (ICD-10 PCS). Maintained by the Center for Medicare and Medicaid Services (CMS). This is used for hospital-based inpatient service reporting.

[In Canada, the Canadian Institute for Health Information (CIHI) maintains one modification - the ICD-10 CA standard.]

The WHO released the most recent version, ICD-11, on June 18, 2018. This will be the first fully electronic version. Member States are now working to translate this into their national languages. Many have also begun the process of developing their clinical modifications. The ability to reporting using ICD-11 will begin as early as January 1, 2022, for some countries. (Canada and the US will likely take much longer to install the newest version.)

At Yale University in the early 1980s, Robert B. Fetter, PhD, and John D. Thompson, MPH developed the DRG classification system.  The intent was to find a way to group inpatients together to help achieve more efficient cost management. A list of ICD diagnosis and comorbidities form the base for each group. To establish a group, more information is then incorporated. This includes things such as: clinical interventions, age, sex, discharge status, and length of stay.

CMS adopted the use of DRGs, for inpatient care reimbursement, in the US in 1983. Since that time, their use has expanded. For each DRG, the payer calculates a payment based on the expected "typical" care and resource use for a patient within the group. (The CMS website is a great resource for more detailed information on DRGs in the US.) There are many DRG systems in use around the world and use of this method seems to be expanding. (There is no international data set - each country determines and maintains their groups for use.)

Canadian Case Mix Groups+ (CMG+)

CIHI currently maintains a similar DRG-type system for Canadian Healthcare, the CMG+.  This classification groups inpatients who use similar resources and have comparable clinical characteristics. Like DRGs around the world, CMGs are used for many things. Including healthcare planning activities, developing estimates for cost expenditures, and evaluating program initiatives.

Current Procedural Terminology (CPT)

Another significant code set that is in use throughout the US is CPT. The American Medical Association administers and maintains the CPT list. First developed in 1966, the original code set focused on surgical procedures only. In 1983, CMS adopted their use and the list was broadened to include more provider services. The future use of CPTs was again solidified in the Health Insurance Portability and Accountability Act (HIPAA) of 1996. This legislation defined CPTs as the standard for the identification of medical procedures. It also established their use in the storage and transmission of health data. In the US today, surgical, medical, and diagnostic procedures and services are all reported using CPT codes.

Canadian Classification of Health Interventions (CCI)

CCIs are complementary to ICD-10 CA. All healthcare organizations in Canada use these codes to classify various care interventions. This is true for both inpatient and outpatient care. The code set includes, but is not limited too, both therapeutic and diagnostic interventions. CIHI is responsible for the development and maintenance of the CCIs.

"The goal is to turn data into information, and information into insight." - Carly Fiorina

Just think ... we haven't even scratched the surface.

There's still LOINC, SNOMED CT, DIN, RxNorm, ICHI, .... and the list goes on :)