ICD-10 and ICF, Better Together

By F. Mark Amundson, PT, DPT, DSc, MA, ATC, SCS, CSCS

The World Health Organization (WHO) recognizes health is on a continuum ranging from; the worst of health conditions to the best of health, the lowest functional ability to the highest.1 WHO developed the International Statistical Classification of Diseases and Health Related Problems (ICD) to describe health conditions.2 Currently the United States health care system uses the tenth edition of the ICD, ICD-10. However, WHO recognized that describing a health condition by solely utilizing ICD-10 terminology does not adequately define the impact health conditions have on function.1

To have a common language for describing the effect health and health related states have on function, WHO developed the International Classification of Functioning, Disability, and Health (ICF).3,4 ICF is a complimentary language to ICD-10.1 Used together ICD-10 and ICF provide a better description of an individual than applied separately. Whereas ICD-10 classifies health conditions that includes injury or illness, ICF classifies the extent those health conditions have on the functional ability of a person. By using ICD-10 and ICF together, health care providers gain a better understanding of an individual’s health status.3, 4

In 2001 the ICF was endorsed by 191 nations including the United States as the standard language and framework for describing health and health-related states. Since then, national health care organizations including the American Physical Therapy Association (APTA).6 Function rather than disability is the cornerstone for ICF that is used as a classification system not a clinical measurement tool.3 ICF terminology is the core to the Centers for Medicare and Medicaid billing codes for physical therapy evaluation and re-evaluation proposed to take effect January 1, 2017.7

A fictional story of Mr. J and Mr. L illustrates how ICD-10 and ICF complement each other in describing the functional difference between two individuals who have the same primary diagnosis. Mr. J and Mr. L are two men with similar personal demographics. Also, in ICD-10 terminology, each has a primary diagnosis of M16.11; Unilateral Osteoarthritis Right Hip. Using that information alone there seems to be little difference between the two men. However, Mr. J is able to go about most of his typical activities with minimal restrictions. Mr. L, on the other hand, experiences severe hip pain that limits his ability to sleep and walk. Hip weakness coupled with the pain results in restricted hip movement and a noticeable lateral sway to the involved lower extremity. He is unable to participate in most of his typical activities at home and in the community.

Here are two men that are similar in many ways including a diagnosis in ICD-10 terms, yet they are very different. ICD-10 is dichotomous, the person either has or does not have a specific health condition.3,4 Little can be learned in regard to the apparent variance in treatment and potential outcomes between the two men by merely referencing a diagnosis. Understanding the current and preferred functional level of the person is required to effectively treat that individual.1,3 In the current example ICF language can provide information to illustrate the differences between these two men with an ICD-10 diagnosis of M16.11.

ICF is based upon health not being dichotomous.3,4,8 Instead of being classified solely by the presence or absence a health condition, health is recognized to be on a continuum from extremes of disability and function.3,4,8 Disability and function are umbrella terms that together span the entire continuum.3,4,8 Disability involves impairments, activity limitations, and participation restrictions.3,4,8 Function is based upon body functions, body structures, activities, and participation.3,4,8 An understanding of these and other ICF terms is required to discover the functional capability of individuals.9 Definitions of some ICF foundational terms as provided by the WHO ICF Research Branch 8 are:

  • Disability is an umbrella term for impairments, activity limitations, and participation restriction. It denotes the negative aspects of the interaction between an individual (with a health condition) and that individual’s contextual factors (environmental and personal factors).
  • Functioning is an umbrella term for body functions, body structures, activities, and participation. It denotes the positive aspects of the interaction between an individual (with a health condition) and that individual’s contextual (environmental and personal factors).
  • Health Condition is an umbrella term for disease (acute or chronic), disorder, injury or trauma. A health condition may also include other circumstances such as pregnancy, ageing, stress, congenital anomaly, or genetic predisposition. Health conditions are coded using ICD-10.
  • Impairment is a loss or abnormality in body structure or physiological function (including mental functions). Abnormality here is used strictly to refer to a significant variation from established statistical norms. (ex: as a deviation from a population mean within measured standard norms) and should be used only in this sense.
  • Body Functions are the physiological functions of body systems, including psychological functions. “Body” refers to the human organism as a whole, and thus includes the brain. Hence, mental (or psychological) functions are subsumed under body functions. The standard for these functions is to be the statistical norm for humans.
  • Body Structures are structural or anatomical parts of the body such as organs, limbs, and their components classified according to body systems. The standard for these structures is considered to be statistical norm for humans.
  • Activity is the execution of a task or action by an individual. It represents the individual’s perspective of functioning.
  • Activity Limitations are difficulties an individual may have in executing activities. An activity limitation may range from a slight to severe deviation in terms of quality or quantity in executing the activity in a manner or to the extent that is expected of people without the health condition.
  • Participation is a person’s involvement in a life situation. It represents the societal perspective of functioning.
  • Participation Restrictions are problems an individual may experience in involvement in life situations. The presence of a participation restriction is determined by comparing an individual’s participation to that which is expected of an individual without disability in that culture or society.
  • Environment Factors constitute a component of ICF, and refer to all aspects of the external or extrinsic world that form the context of an individual’s life and, as such, have an impact on that person’s functioning. Environmental factors include the physical world and its features, the human made physical world, other people in different relationships and roles, attitudes and values, social systems and services, and policies, rules and laws.
  • Personal Factors are contextual factors that relate to the individual such as age, gender, social status, life experiences and so on, which are not currently classified in ICF but which users may incorporate in their applications of the classification.

Now by applying ICF terms in the story of Mr. J and Mr. L their differences become more obvious. Simply put, Mr. J functions at a higher functional level than Mr. L. Activity limitations are the primary concern of Mr. J. He has impairments, however their severity is low. Meanwhile Mr. L is experiencing much more severe impairments that include pain, weakness, and decreased movement. Due to these impairments he is significantly more limited in activities including sleeping and walking. Participation in many of his typical activities is severely restricted to being out of the question. Upon reviewing this preliminary information, the variations between these two men begins to evolve.

Currently there is clearly a difference between these two, essentially identical men, who have been given the same diagnosis in ICD-10 terminology of M16.11; Unilateral Osteoarthritis Right Hip. By adding in ICF terminology their disparity begins to evolve. Now the challenge is to narrow in on these impairments, activity limitations, and participation restrictions to understand each man’s current and desired functional capability. Linking ICD-10 diagnosis to ICF information is an initial step to learn where the functional capability of an individual is on the health continuum. Knowledge that helps to determine the right level of health care for each individual.


1. Stucki G, Cieza A, Melvin J. The international classification of functioning, disability and health: a unifying model for the conceptual description of the rehabilitation strategy. J. Rehab Med 2007; 39:279-285.

2. World Health Organization. International Statistical Classification of Diseases and Related Health Problems – 10th revision, Vol. 2. Geneva: World Health Organization; 2010.

3. Towards a Common Language for Functioning, Disability, and Health (ICF). Geneva: WHO; 2002.

4. World Health Organization. International Classification of Functioning, Disability and Health: ICF. Geneva: World Health Organization; 2001.

5. World Health Organization. How to use the ICF: Using the International Classification of Functioning, Disability, and Health (ICF). Exposure draft for comment. October 2013. Geneva: WHO.

6. Bemis-Dougherty A. Practice matters: what is the ICF? PT Magazine of Physical Therapy. 2/09

7. Centers for Medicare & Medicaid Services: Medicare Program; Revisions to Payment Policies Under the Physician Fee Schedule and Other Revisions to Part B for CY 2017; Medicare Advantage Pricing Data Release; Medicare Advantage and Part D Medical Low Ratio Data Release; Medicare Advantage Provider Network Requirements; Expansion of Medicare Diabetes Prevention Program Model. (Section II.L.5.b.36). Proposed Rule: 7/15/16

8. World Health Organization. ICF Research Branch. ICF e-Learning Tool Glossary of Terms. Accessed: 8/11/16.

9. Rauch A, Cieza A, Stucki G. How to apply the international classification of functioning, disability and health (ICF) for rehabilitation management in clinical practice. Eur J Phys Rehabil Med 2008:44;329-342.

F. Mark Amundson PT, DPT, DSc, MA, ATC, SCS, CSCS, is a PPS member and chief clinical officer of Twin Boro Physical Therapy a private practice with 22 outpatient clinics in New Jersey. He can be reached at famundson@twinboro.com.

Copyright © 2018, Private Practice Section of the American Physical Therapy Association. All Rights Reserved.

Are you a PPS Member?
Please sign in to access site.
Enter Site!