Understanding Function in RA: Importance and Measurement


Musculoskeletal problems are some of the main reasons why patients go to physicians or other health care professionals.

ABSTRACT: The reasons why patients go to physicians to seek help for musculoskeletal problems, such as pain, difficulty in climbing stairs, and reduced work time, all are aspects of human function but refer to different aspects of function. In 2001, the World Health Organization published a classification to describe the health components of functioning and disability. Included is the entirety of a person's health rather than just the consequences of his or her disease. Patient self-report measures, used in conjunction with routine office visits, provide a practical and feasible way of obtaining information about functional health. The Health Assessment Questionnaire, a frequently used tool, has played a major role in broadening the perspective of chronic disease management from biomedical measurements to include measurement of functional health. (J Musculoskel Med. 2012;29:41-43)

Musculoskeletal problems are some of the main reasons why patients go to physicians or other health care professionals. The reasons for seeking help are quite variable. For example, a person may be experiencing persistent knee pain after a fall or noticing increased difficulty in walking up stairs or feeling that he or she is no longer able to work full-time because of joint symptomatology.

Although pain, difficulty in climbing stairs, and reduced work time all are aspects of human function, they refer to very different aspects of function-pain focuses on a part of the body, climbing stairs emphasizes a specific activity, and work time highlights a social role. In turn, these distinctions can have significant implications for the patient's assessment and treatment.

Variations in application of the term “function” also can prevent clear communication about functional problems among physicians and between physicians and their patients. The rheumatologist typically uses function in relation to a joint, the nurse in relation to a specific activity, and the occupational therapist in regard to a social role.

This is the second article in a 5-part series designed to provide a practical approach to better understanding of function in rheumatoid arthritis (RA). The first article (“Understanding Function in RA: An Update on ‘Treat to Target,’” The Journal of Musculoskeletal Medicine, February 2012, page 10) provided an overview. In this second article, we first present a standardized vocabulary for describing function, based on the World Health Organization's (WHO's) International Classification of Functioning, Disability and Health (ICF) and then apply it to an assessment tool frequently used in rheumatology, the Health Assessment Questionnaire (HAQ). Upcoming articles will discuss how function is assessed in RA, how functional assessment may be incorporated into clinical practice, and the role of the nurse in multidisciplinary RA care.


In 2001, the WHO published a classification-to be used in conjunction with the International Statistical Classification of Diseases and Related Health Problems (ICD-10)-to describe the health components of functioning and disability, namely, the ICF.1 Included in the ICF is the entirety of a person's health rather than just the consequences of the disease.

Classification Parts and Components

The ICF classification has 2 major parts. The first part, labeled Functioning and Disability, identifies and defines various types of human function. It has 2 components, Body Functions and Structures, and Activities and Participation.

Body Functions and Structures refers to issues related to body systems, such as the joints, bones, and structures of the upper extremity. Dysfunctions in these body systems and functions, called impairments, include pain, joint contractures, and muscle weakness. In the ICD-10, impairments are the signs or symptoms of disease.

In Activities and Participation, the second component of Functioning and Disability, “activity” refers to function at the level of the person rather than a body system and relates to the performance of tasks or actions. Stair climbing, bathing, dressing (Figure), cooking, and vacuuming are examples that illustrate the wide spectrum of activities.

Dysfunctions in activities are called activity limitations. Participation relates to a person's involvement in a life situation, such as being a caregiver, student, secretary, or plumber. Dysfunctions in participation are called participation restrictions. Although there is no clear distinction between activities and participation, the latter typically involves a sequence of tasks and has a social aspect; activities may not have these features.

The second part of the ICF classification, labeled Contextual Factors, is composed of Environmental and Personal Factors. These are factors that can significantly modify functional health, which encompasses the unique characteristics of a person that are considered in management interventions.

Environmental Factors include the various physical, social, and attitudinal environments in which patients live, work, and play. Stairs, lack of handicapped parking, and colleagues who do not understand fluctuations in functional health associated with arthritis are examples of negative environmental factors; low-rise ramps, adequate handicapped parking spaces, and hiring policies that implement reasonable accommodations (as defined by the Americans with Disabilities Act) are positive environmental factors. The Environmental Factors component of the ICF directs attention to these determinants of function.

Note that Personal Factors encompass individual characteristics that are not a part of the health condition per se but may have a significant influence on it. Examples are the person's sex, age, race, and education level.

A Standardized Vocabulary

Thus, the Functioning and Disability part of the ICF provides a standardized vocabulary for designating dysfunction at the organ or organ system level (impairment), personal level (activity limitations), and societal level (participation restrictions). The Contextual Factors part includes the multitude of factors that can modify a person's health and functional ability.


The Multidimensional Health Assessment Questionnaire (MDHAQ), a simplification of the original tool, retained 8 self-care activities, including “dress yourself.”

Although management of patients' impairments (abnormalities of body functions and structures) is a key to improving health, it does not necessarily reduce activity limitations or participation restrictions. Assessing manifestations of function as described by the ICF, and then providing interventions specific for them, helps health care providers improve patients' functional health, which, in turn, can affect biological health. Patient self-report measures, used in conjunction with routine office visits, provide a practical and feasible way of obtaining information about functional health.


Many valid, reliable, and responsive self-report measures are available. The HAQ, a frequently used tool,2 was developed by Dr James Fries at the Stanford Arthritis Center in 1980. It was among the first “patient reported outcome” measures.

The HAQ has played a major role in broadening the perspective of chronic disease management from biomedical measurements to include measurement of functional health. Routine measurement of activities, and to some extent participation on the HAQ, helps define the consequences of the health condition (arthritis) and medical management on daily functions.

20 Questions in 8 Categories

The HAQ Disability Index (HAQ-DI) has 20 questions in 8 categories: dressing and grooming, arising, eating, walking, hygiene, reach, grip, and activities. Each category has 2 or 3 questions. Patients rate questions on a 0 to 3 scale: 0 means without difficulty; 1, with some difficulty; 2, with much difficulty; and 3, unable to do. The most limited activity in a category determines the category score. Use of assistive devices (eg, button hook) to perform an activity is taken into consideration in the scoring.

The HAQ-DI is the average score of the 8 categories; it ranges from 0 to 3. Three additional items in the HAQ-DI query general physical ability, pain, and general health.

In 1999, Pincus and associates3 modified the HAQ-DI to simplify it and to incorporate evaluation of more strenuous activities. This modification, known as the Multidimensional Health Assessment Questionnaire (MDHAQ), retained 8 items from the original HAQ-dress yourself, including tying shoelaces and doing buttons; get in and out of bed; lift a full cup or glass to mouth; walk outdoors on flat ground; wash and dry entire body; bend down to pick up clothing from the floor; turn regular faucets on and off; and get in and out of car, bus, train, or airplane.2 The 6 more advanced activity/participation items that were added are run errands and shop, climb up a flight of stairs, walk 2 miles, run or jog 2 miles, drive a car 5 miles from your home, and participate in sports as you would like.4

The MDHAQ also includes 4 psychological items: depression, anxiety, sleep disturbance, and stress. The ICF would classify these items as impairments because they reflect organ system dysfunction. Separate average scores are calculated for the original HAQ activities, the advanced activities, and the psychological items; patients rate all items using the 4-point ordinal scale.

Ideal Instrument for Developing an Assessment

The emphasis on self-care activities and the inclusion of impairment items make the MDHAQ an ideal instrument for developing an assessment for the physician's office. Because participation involves activities that are community-based, such as shopping, observing these activities in the office is very difficult.

As a self-report measure, the MDHAQ has the same limitations as other self-report measures of function. First, patients are not always able to identify the presence and extent of activity limitations accurately, especially if they have not done an activity recently. Overestimating or underestimating activity limitations is common. Research suggests that the degree of disagreement between self-report and actual performance varies with the type of activity; the range is from 30% to 50%.5

Second, self-report instruments indicate that an activity is difficult for the patient but not what about it causes difficulty. Patients may recognize that they have a problem but not specifically what is causing it or what could be done.

These 2 limitations suggest that assessment of activity should include observation of patients performing activities to identify what is causing the difficulty. The MDHAQ questions provide an ideal anchor for individual patient assessment in the physician's office.

The next article will describe how impairments in body systems caused by RA can affect function and how patients can adapt their activities to cope with these impairments. Methods to obtain information about patient function will be reviewed, including observations of activity performance during an office visit.



1. World Health Organization. International Classification of Functioning, Disability and Health (ICF). Geneva: World Health Organization, 2001. http://www.who.int/classifications/icf/en. Accessed February 2, 2012.

2. Fries JF, Spitz P, Kraines RG, Holman HR. Measurement of patient outcome in arthritis. Arthritis Rheum. 1980;23:137-145.

3. Pincus T, Swearingen C, Wolfe F. Toward a multidimensional Health Assessment Questionnaire (MDHAQ): assessment of advanced activities of daily living and psychological status in the patient-friendly health assessment questionnaire format. Arthritis Rheum. 1999;42:2220-2230.

4. Pincus T, Sokka T, Kautiainen H. Further development of a physical function scale on a MDHAQ [corrected] for standard care patients with rheumatic diseases [published correction appears in J Rheumatol. 2005;32:2280]. J Rheumatol. 2005;32:1432-1439.

5. Rogers JC, Holm MB, Beach S, et al. Concordance of four methods of disability assessment using performance in the home as the criterion method. Arthritis Rheum. 2003;49:640-647.

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