ICD-9-CM to ICD-10-CM: Implementation Issues and Challenges

Anita Hazlewood, MLS, FAHIMA, RHIA, University of Louisiana at LaFayette


ICD-9-CM is the United States’ modification of the International Classification of Diseases, Ninth Revision, developed by the World Health Organization. It is the most universally applied classification system for coding diagnoses, reasons for healthcare encounters, health status, and external causes of injury. The regulations regarding electronic transactions and code sets promulgated under HIPAA designate ICD-9-CM as the medical code set standard for diseases, injuries, or other encounters for healthcare services.

In testimony before Congress in May 2002, Sue Prophet, AHIMA’s director of coding policy and compliance, testified that “AHIMA believes that adoption of a replacement for the ICD-9-CM diagnosis codes is an absolute necessity, as ICD-9-CM is more than 20 years old (implemented in 1979) and has become outdated and obsolete.” 1

There are several problems with this current classification system including:

  • The ICD-9-CM Tabular List is running out of numbers to assign for codes and in some cases, new code proposals could not be adopted because of the limited space.
  • The current ICD-9-CM diagnosis codes do not provide sufficient clinical specificity to describe the severity or complexity of the various disease conditions. In particular, the codes for healthcare encounters for other than disease (V codes) do not provide enough specificity. Consequently, there are increasing requirements for submission of additional documentation in order to support claims.
  • The exchange of meaningful healthcare data with healthcare organizations and professionals around the world is hindered by the fact that many countries are presently using ICD-10 or a clinical modification of it (Australia and Canada, for example, have modifications). Even in the US, mortality statistics (information on death certificates) have been collected using ICD-10 since 1999.
  • The current ICD-9-CM system is ineffective for effectively monitoring utilization of resources, measuring performance, and analyzing healthcare costs and outcomes.

Historically, ICD-9-CM was developed as a classification system for statistical compilation of data in inpatient settings. Unfortunately, it has proven to be inadequate for use in other healthcare settings and even for reimbursement purposes. The cornerstone of DRGs, RUGs, and other prospective payment groups is the ICD-9-CM code. Even non-PPS payment methodologies require complete, accurate, and detailed coding in order to calculate appropriate reimbursement rates, determine coverage, and establish medical necessity.

There are many uses of coded data, including:

  • Designing payment (reimbursement) systems with emphasis on the processing of claims specifically for reimbursement,
  • Measuring the safety, quality, and efficacy of medical care,
  • Designing delivery systems and setting healthcare policy,
  • Monitoring the utilization of resources while improving financial, clinical, and administrative performance,
  • Providing healthcare consumers with data regarding the cost and outcome(s) of various treatment options,
  • Identifying, tracking, and managing public health risks and disease processes,
  • Recognizing and identifying abusive or fraudulent reimbursement practices and trends, and
  • Conducting healthcare research and clinical trials and participating in epidemiological studies.2
Keeping all of the above uses in mind, it becomes quite clear that a classification system that provides greater coding accuracy and specificity is greatly needed. Several other organizations have called for Congress to adopt ICD-10-CM, including the American Hospital Association, the Advanced Medical Technology Association, the American Psychiatric Association, and the Federation of American Hospitals.

In 1994, WHO developed the tenth revision of the ICD system. The purpose of the revision was to expand the content, purpose, and scope of the system and to include ambulatory care services, increase clinical detail, capture risk factors in primary care, include emergent diseases, and group diagnoses for epidemiological purposes.

In 1997, the National Center for Health Statistics began the first round of testing following the development of ICD-10-CM. A timetable for the implementation of ICD-10-CM has not been determined. Many of the problems with ICD-9-CM have been addressed in ICD-10-CM. It provides better information for nonacute care or nonhospital encounters, clinical decisionmaking, and outcomes research. Terminology and disease classification have been updated to be consistent with current usage and medical advances.

Before continuing with a discussion of ICD-10-CM and the benefits of adopting this system, a review of HIPAA’s requirement for code sets would be appropriate.

Code Sets

In August of 2000, the Department of Health and Human Services released the final rule for transaction and medical code sets as established under the Health Insurance Portability and Accountability Act (HIPAA). To be designated as a HIPPA standard, a code set had to:
  • Improve the efficiency and effectiveness of the healthcare system by leading to cost reductions for or improvement in benefits from electronic healthcare transactions,
  • Meet the needs of the health data standards user community, particularly healthcare providers, health plans, and healthcare clearinghouses,
  • Be consistent and uniform with other HIPAA standards—their data element definitions and codes and privacy and security requirements; secondarily, with other private and public sector health data standards,
  • Have low additional development and implementation costs relative to the benefits of using the standard,
  • Be supported by an ANSI-accredited standards developing organization or other private or public organization that will ensure continuity and efficient updating of the standard over time,
  • Have timely development, testing, implementation, and updating procedures to achieve administrative simplification benefits faster,
  • Be technologically independent of the computer platforms and transmission protocols used in electronic health transactions, except when they are explicitly part of the standard,
  • Be precise and unambiguous, but as simple as possible,
  • Keep data collection and paperwork burdens on users as low as is feasible, and
  • Incorporate flexibility to adapt more easily to changes in the healthcare infrastructure, such as new services, organizations, provider types, and information technology. 3
This final rule designated five medical code sets to be used for assigning diagnoses and procedures. These are:
  • International Classification of Diseases, 9th Edition, Clinical Modification (ICD-9-CM)
  • Current Procedural Terminology, 4th Edition (CPT-4)
  • Health Care Common Procedural Coding System (HCPCS)
  • Code on Dental Procedures and Nomenclature, 2nd Edition (CDT-2)
  • National Drug Codes (NDC)
    Note: The mandated use of these codes for use by nonretail pharmacy transactions was repealed by HHS in 2003.
This final rule was effective on October 16, 2000. Most entities had to be in compliance by October 16, 2002, although some smaller entities had until October 16, 2003, to be compliant. Various organizations have recommended that the Department of Health and Human Services should issue a proposed rule requiring that facilities adopt the new ICD-10-CM codes as the national standard code set.

In testimony before Congress on May 29, 2002, Sue Prophet, director of coding policy and compliance of the AHIMA, indicated that “The level of specificity in ICD-10-CM will provide payers, policy makers, and providers with more detailed information for establishing appropriate reimbursement rates, evaluating and improving quality of patient care, improving efficiencies in healthcare delivery, reducing healthcare costs, and effectively monitoring resource and service utilization.” 4 AHIMA, believes that ICD-10-CM represents a “significant improvement over both ICD-9-CM and ICD-10.” 5

Benefits of Implementing ICD-10-CM

Generally, ICD-10-CM incorporates greater specificity, clinical data, and information relevant to ambulatory and managed care encounters. In addition, the structure of ICD-10-CM allows for the possibility of greater expansion of code numbers. This classification will also extend beyond simply the classification of disease and injuries to include risk factors that are frequently encountered in a primary care setting. The new system also includes those diseases discovered since the most recent revision of ICD-9-CM. General terminology, as well as disease classification, has been updated to be consistent with accepted and current clinical practice. The expanded degree of specificity should provide more detailed information, which would assist providers, payers, and policy makers in establishing appropriate reimbursement rates, improving the delivery of healthcare, improving and evaluating the overall quality of patient care, and effectively monitoring both service and resource utilization.

Brief Comparison of ICD-9-CM and ICD-10-CM

ICD-10-CM was designed to offer significant advantages over ICD-9-CM. These changes should result in major improvements in both the quality and uses of data for various healthcare settings.

Significant improvements in both the content and the format of ICD-10-CM include the following:

General Changes and Overall Improvements

  • ICD-10-CM codes are alphanumeric and include all letters except "U," thus providing a greater pool of code numbers.
  • ICD-9-CM’s V and E codes are incorporated into the main classification in ICD-10-CM.
  • The length of codes in ICD-10-CM can be a maximum of seven characters (digits and letters) as opposed to ICD-9-CM’s five digits.
  • ICD-10-CM offers the addition of information relative to ambulatory and managed care encounters.
  • Conditions that are new or that were not uniquely identified in ICD-9-CM have been assigned code numbers in ICD-10-CM.
  • In ICD-10-CM, some three-character categories are not used in order to allow for revisions and future expansion.
  • Instead of grouping by categories of injury or type of wound, ICD-10-CM groups injuries by site of the injury and then the type.
  • Excludes notes were expanded in order to provide guidance on the hierarchy of the chapters and to clarify priority of code assignment.
  • Some conditions with a new treatment protocol or perhaps a recently discovered or new etiology have been listed in a more appropriate chapter.
  • Combination codes are used for both symptom and diagnosis, and etiology and manifestations—for example K50.03 Crohn’s disease of small intestine with fistula.
  • Codes for postoperative complications have been expanded. Also a distinction has been made between intraoperative complications and post-procedural disorders—for example, K91 Intraoperative and postprocedural complications and disorders of digestive system, NEC.

Implementation of ICD-10 in other Countries

ICD-10 has been in use in other countries for several years. AHIMA surveyed several other countries regarding their implementation strategies and obstacles that they encountered. AHIMA discovered that many other countries are disgruntled regarding the failure of the US to adopt the revision of ICD-10, again noting the inability to accurately compare data Worldwide.

As mentioned previously, both Australia and Canada have developed modifications of ICD-10 for use in their respective countries. (ICD-10-AM and ICD-10-CA were developed with permission of WHO, as was ICD-10-CM). ICD-10-AM has been fully implemented in Australia since approximately 1999, and most of Canada has completed the conversion. Canada has an entirely electronic ICD-10 product—no paper ICD-10-CA codebooks are available.

Australia conducted two-day training workshops for experienced coding professionals, while Canada provided coding education in a three-phase plan. The first phase consisted of a self-learning package that required about 21 hours to complete. The second phase consisted of a two-day workshop, with a hands-on program. In the third phase, a self-learning package of 10 case studies was provided to the coders. All of the education in Canada involved the use of coding software and not codebooks. Both countries offer periodic refresher courses. The average learning curve was four to six months and coding professionals reported that they did not find ICD-10 any more or less difficult to learn than ICD-9.

Implementation of ICD-10-CM in the US

The Standards and Security Subcommittee of the National Committee on Vital and Health Statistics has mandated that HHS begin a study to analyze the costs and benefits associated with designating ICD-10-CM as the code set to be used. The information obtained through this study will be used, as appropriate, to move the regulatory process forward.

Just as was done in Australia, the first step in designing an implementation strategy for an individual facility should be to create a “party,” committee, team, or task force to oversee the implementation process. Certainly, upper management should be represented as well as all departments affected in any way by the change. At the very least, there should be representatives from the HIM department, information systems or services, billing department, accounting department, human/personnel resources, and physicians. The frequency of meetings will depend on the individual facility, as will the responsibilities of this task force.

One of the first questions to ask is “Who will be affected by the change to ICD-10-CM?” There is a greater impact on more individuals as the uses of coded data have changed so much since the adoption of ICD-9-CM over 23 years ago. Obviously, coders and physicians will require training, but there are other individuals who will be affected and thus, will need some training depending on their involvement.

Training on the new coding system may take many forms including face-to-face workshops or seminars. Currently, there are a number of excellent coding publications dedicated to coding training, and it is expected that this, too, will be the case for ICD-10-CM. Audioseminars, which deliver the information to a large audience, are very cost effective as no travel is involved. Certainly, Web-based training will play an important role in the training of all affected individuals. Various methodologies should be employed as different groups of individuals might respond to one type of training more than another. For instance, physicians may prefer face-to-face training to a Web-based training program.

Educators in coding certificate programs, health information technology programs, and health information administration programs will have the task of educating new coders. As mentioned earlier, different populations of individuals will require training.

Coding professionals: While ICD-10-CM has many differences from ICD-9-CM, the new classification system does retain the traditional format and many of the same characteristics and conventions and thus, should not be too difficult for experienced coders to achieve coding proficiency. An additional problem that could be encountered is a shortage of credentialed, professional coders. Currently, there is a shortage of coders skilled in both ICD-9-CM and CPT coding, and some coders may opt to retire before learning an entirely new system thus exacerbating the problem. Labor statistics predict a shortage of trained coders in the next several years.

Physicians: Physician documentation has been an obstacle to complete and accurate coding for quite some time. With the increased specificity in ICD-10-CM, this issue will continue to be an essential element to collection of good statistical data as well as the key to appropriate reimbursement.

Other healthcare professionals: Again, because of the many uses of coded data, there are multiple categories of users of coded data. These users will require varying levels of training depending on their involvement with coded data. Some of these users include:

  • Nonphysician clinicians/ancillary department personnel
  • Quality management personnel
  • Utilization management personnel
  • Data quality/data security personnel
  • Researchers/data analysts/epidemiologists
  • Software vendors
  • Information systems personnel
  • Billing/accounting personnel
  • Compliance officers
  • Auditors
  • Fraud investigators
  • Government agency personnel

Major Changes from ICD-9-CM to ICD-10-CM

In general, most of the changes were of the following types:
  • Grouping of codes—Conditions have been grouped in a more logical fashion than in ICD-9-CM. This may have been accomplished by means of movement from one chapter to another or one section to another. Many codes have been added to, deleted from, combined, or moved in ICD-10-CM. ICD-10-CM boasts of some chapters that are entirely unique, although these codes were found in other chapters in ICD-9-CM.
  • More complete descriptions—In ICD-10-CM, the subcategory titles are usually complete so that the coder does not have to read previous codes to understand the meaning of the code.
  • Fifth and sixth characters—Fifth and sixth characters are incorporated into the code listing rather than having common fifth digits listed at the beginning of a chapter, section, or category.
  • Laterality—ICD-10-CM incorporates laterality of conditions or injuries at the fifth or sixth character level.
  • Increased specificity—ICD-10-CM offers greatly expanded detail for the various conditions. Many categories, which in ICD-9-CM were limited to three or four digits, have fifth, sixth, and even seventh characters/extensions in ICD-10-CM. In some cases, single ICD-9-CM codes were split into several ICD-10-CM codes to provide greater specificity.
  • Excludes notes—There are three kinds of excludes notes that are used in ICD-10-CM.
  • Use of extensions—Extensions are used in ICD-10-CM to provide additional information. These extensions are most often found in the injury codes but are found in other chapters. 57
  • Combination codes—There are numerous codes in ICD-10-CM that group etiology and manifestation. In ICD-9-CM, generally two codes are required to code etiology and manifestation.
  • Terminology used—Many of the category code or subcategory code titles have been changed to reflect new technology and more recent medical terminology.
  • Postprocedural conditions—There are many more codes added to ICD-10-CM to describe postoperative or postprocedural conditions.
  • Trimester specificity—ICD-10-CM codes in the pregnancy, delivery, and puerperium chapter includes codes designating the trimester in which the condition occurs.
  • New codes—There are many new codes to ICD-10-CM that were not classified in ICD-9-CM. Notably, codes for blood type and alcohol level are included in ICD-10-CM.

The increased specificity of the ICD-10-CM codes makes complete and accurate documentation increasingly important with the implementation of the new system. Health information management supervisors and coders will have to assist the physicians in becoming more aware of what documentation is needed. Likewise, radiologists and pathologists will need to be reminded about the types of information that will need to be available for coders to correctly assign codes. Medical record forms and/or computer fields may need to be reviewed and revised to incorporate data that will be needed to assign codes. This review of forms and/or computer fields should begin many months prior to the adoption of ICD-10-CM.

As evidenced by the experiences in Australia and Canada, successful transition to the ICD-10-CM classification system will require long range planning by healthcare facilities. It is not simply HIM professionals who are affected, but healthcare professionals across many disciplines. In addition, third-party payers including the federal government will need to be trained in the use of the new classification system. Coding professionals have the training and experience to limit the learning curve involved in transitioning to the new system, and HIM professionals are certainly ready to take the lead in retraining and education for new and experienced users of health data.

Let us begin planning for ICD-10-CM and enjoy the benefits of this greatly improved classification system.


  1. Testimony by Sue Prophet before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.ahima.org/dc/comments.ncvhs.052902.cfm.
  2. Testimony by Sue Prophet before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.ahima.org/dc/comments.ncvhs.052902.cfm.
  3. Federal Register 63, no. 8, May 7, 1998; p. 25274. Available at www.access.gpo.gov/su_docs/aces/aces140.html.
  4. Testimony by Sue Prophet before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.ahima.org/dc/comments.ncvhs.052902.cfm.
  5. Testimony by Sue Prophet before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.ahima.org/dc/comments.ncvhs.052902.cfm.


Federal Register 63, no. 8, May 7, 1998; p. 25272–25320. Available at www.access.gpo.gov/su_docs/aces/aces140.html.

Federal Register 65, no. 160, August 17, 2000; p. 50311–50372. Available at www.access.gpo.gov/su_docs/aces/aces140.html.

Ingenix Coding Lab: Implementing ICD-10. Ingenix, Inc.: Reston, Virginia. 2002.

Innes, Kerry, Peasley, Karen, and Roberts, Rosemary. “Ten Down Under: Implementing ICD-10-CM in Australia.” Journal of the American Health Information Management Association 71, no.1 (2000): 52-56.

November 20, 2002 letter to members of the National Committee on Vital and Health Statistics, an advisory body to HHS, from the American Hospital Association, Advanced Medical Technology Association, and the Federation of American Hospitals. Available at http://www.healthdatamanagement.com/HDMSearchResultsDetails.cfm?DID=135122.

Testimony by Sue Prophet before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.ahima.org/dc/comments.ncvhs.052902.cfm

Testimony by Dr. Steven Mirin before members of the National Committee on Vital and Health Statistics (NCVHS), Standards and Security Subcommittee. May 29, 2002. Available at http://www.psych.org/pub_pol_adv/dsmiv_testimonyncvhs52902.cfm.

Source: AHIMA's 75th Anniversary National Convention and Exhibit Proceedings, October 2003