A Brief History of ICD-10-PCS
by Robert Mullin, MD, FACS
The International Classification of Diseases, Tenth Revision, Procedure
Coding System (ICD-10-PCS) was developed as a replacement for the International
Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
volume 3, Procedures. This version of ICD, in use since January 1979,
originated in the International Classification of Procedures in Medicine
(ICPM). The ICPM was published by the World Health Organization (WHO)
in 1978 for trial purposes. The classification consisted of nine chapters,
with the first digit of the three- or four-digit code denoting the chapter
number. The Health Care Financing Administration (HCFA) is responsible
for the maintenance of volume 3.
The ICD-9-CM Coordination and Maintenance Committee (C&M)which
holds public meetings and receives public commentswas established
in 1985 by the Department of Health and Human Services (HHS). The first
revisions to ICD-9-CM volumes 1, 2, and 3 took place in 1986. Since then,
the C&M has made annual additions and deletions. It soon became apparent
that with the limitation of a four-digit system, there was little room
to make substantive changes. In 1992, HCFA decided a more organized approach
was needed and funded a project with 3M Health Information Systems to
produce a preliminary design for a replacement of ICD. After studying
the problem, 3M concluded that a completely new system would be the best
solution. An alphanumeric, multiaxial, seven-digit scheme was adopted
and a prototype was developed using the respiratory and cardiovacular
chapters. Interested in this approach, HCFA funded the development of
several more chapters, at which point the endocrine, lympathic, hemic,
and urinary chapters were revised. However, it quickly became obvious
that the project could only be accomplished by changing the entire procedure
coding system at the same time. This was important because there was a
great deal of overlap between the various chapters. HCFA decided to move
ahead with a complete revision and requested competitive bids for a three-year
project to replace volume 3, based on the scheme developed in the two
trial projects. The new system, to be titled the International Classification
of Diseases, Tenth Revision, Procedure Coding System (ICD-10-PCS), was
to replace ICD-9-CM procedure codes for reporting Medicare inpatient procedures.
HCFA awarded the contract to 3M in 1995, with the following timetable:
- year 1complete first draft of ICD-10-PCS
- year 2develop training program and informal testing and revise
- year 3formal testing by independent contractor and final revision
Objectives, essential characteristics, and general guidelines were stipulated
at the outset.
The objectives were to develop a new procedure coding system, improve
accuracy and efficiency of coding, reduce training efforts, and improve
communication with physicians. The essential characteristics were:
- a unique code for all substantially different procedures
- a system structure that allows incorporation of new procedures as
- standard terminologythe coding system includes definitions
of the terminology used. While the meaning of the specific words can
vary in common usage, the coding scheme does not include multiple meanings
for the same term. Each term is assigned a specific meaning
- multiaxialthe system has a multiaxial structure with each code
character possessing the same meaning within the specific procedure
section and across procedure sections to the extent possible
General guidelines included:
- not including diagnostic information in the procedure description
- limiting the not otherwise specified (NOS) option
- not allowing a not elsewhere classified option (NEC), except for
- defining all possible procedures
The system is based on a seven-character, alphanumeric code using the
digits 0 to 9, and the letters A-H, J-N, P-Z.
The system was completed during the first year, and informal testing
was carried out in the second year. Revisions were made based on comments
and suggestions from the testing, and a working draft was completed. During
phase three, the Clinical Data Abstraction Centers (CDACs)consisting
of FMAS in Columbia, MD, and DYNEKePRO in York, PAtested the system
by coding 5000 records, identifying revisions as needed, and providing
feedback on any problematic issues that arose. Additional comparison tests
of 100 records coded in both ICD-9-CM and ICD-10-PCS were then made by
The CDACs concluded the system was more complete than ICD-9-CM, contained
greater specificity and detail, and was easy to expand. They found that
the multiaxial structure made it easier to analyze, and the standardized
terminology made it easier to use once the coder had initial training.
They felt that the system should lead to improved accuracy and efficiency
of coding. They also concluded that while training time will be a factor
since it is quite different from ICD-9-CM, having all of the terms defined
will make it easier to teach. Of interest is the fact that once basic
knowledge is acquired, the coders did not need to use the index. However,
several modifications resulted from this testing, including revisions
to the training manual and additions to the index.
A final draft of the system was completed and submitted to HCFA in March
1998, and a final report submitted in December 1998. The entire ICD-10-PCS,
a complete map of ICD-10-PCS to ICD-9-CM volume 3, mapping file, and a
set of speaker's slides are available on the HCFA Web site at www.hcfa.gov/stats/icd10/icd10.htm.
Last year, in coding a sample of ambulatory cases, the CDACs reached
the same conclusions as the inpatient record coding study. Participating
coders were not involved in the initial round of testing. The second set
of coders were able to use the system with ease.
At the December 1998 C&M meeting, participants suggested that a test
of obstetrical and pediatric and more non-Medicare cases should be performed.
The American Hospital Association (AHA) and the American Health Information
Management Association (AHIMA) volunteered to solicit these types of cases
for the study. Developments involving ICD-10-PCS can be followed by reading
reports of the ICD-9-CM C&M meeting reports on HCFA's homepage at www.hcfa.gov.
Click on Events, Meetings and Workgroups, then click on Current Workgroups
Robert L. Mullin is a healthcare consultant in Wallingford, CT. He
can be reached at Robertmd@aol.com.
Mullin, Robert. "A Brief History of ICD-10-PCS." Journal
of AHIMA 70, no. 9 (1999): 97-98.