Measures of Adult General Functional Status

Transcription

1 Arthritis Care & Research Vol. 63, No. S11, November 2011, pp S297 S307 DOI /acr , American College of Rheumatology MEASURES OF FUNCTION Measures of Adult General Functional Status SF-36 Physical Functioning Subscale (PF-10), Health Assessment Questionnaire (HAQ), Modified Health Assessment Questionnaire (MHAQ), Katz Index of Independence in Activities of Daily Living, Functional Independence Measure (FIM), and Osteoarthritis- Function-Computer Adaptive Test (OA-Function-CAT) DANIEL K. WHITE, JESSICA C. WILSON, AND JULIE J. KEYSOR INTRODUCTION Dr. White s work was supported by an American College of Rheumatology Research and Education Foundation Rheumatology Investigator Award, the Boston Claude D. Pepper Older Americans Independence Center (P30- AG031679), and the Foundation for Physical Therapy. Daniel K. White, PT, ScD, Jessica C. Wilson, PT, Julie J. Keysor, PT, PhD: Boston University, Boston, Massachusetts. Address correspondence to Daniel White, PT, ScD, Clinical Epidemiology Research and Training Unit, 650 Albany Street, X200, Boston, MA dwtbn@bu.edu. Submitted for publication January 24, 2011; accepted in revised form May 10, Self-reported measures to assess and quantify functional status are important tools for clinicians and investigators. These measures qualify limitation with different types of functional activities and quantify the extent of limitation. We are particularly interested in measures of general functional status. Although these generic measures of function were originally developed in other patient populations, they are relevant to the field of rheumatology. In particular, these instruments have been found to be valid and reliable measures of function, sensitive to changes in function, and have distinct thresholds for important change in people with rheumatologic disease. Some notable studies have been added to the literature for general functional status measures in the last decade. Most of these additions are in the area of identifying thresholds for minimum clinically important difference, i.e., the smallest amount of change associated with a minimally important decline or improvement in function. To reflect changes in clinical practice over the last decade, we chose to review the Functional Independence Measure, which is a commonly used measure in practice to assess function. Also, Computer Adaptive Testing has developed over the past decade, which represents an innovative and exciting change to how self-reported tests of function are administered. Therefore, the purpose of this report is to provide an update to measures of general functional status commonly employed for people with rheumatologic diseases and provide a review of a Computer Adaptive Testing measure of functioning for people with osteoarthritis. SF-36 PHYSICAL FUNCTIONING SUBSCALE (PF-10) Purpose. The PF-10 is a generic outcome measure designed to examine a person s perceived limitation with physical functioning (1) and is a subscale within the Medical Outcomes Study 36-item Short Form Health Survey (SF-36). Content. Subjects are asked if their health limits physical activity, basic mobility, and basic activities of daily living. Number of items in scale. There are 10 items. Response options/scale. Responses are rated on a Likert scale. For the SF-36 versions 1.0 and 2.0, each item is rated on a 3-point scale (yes, limited a lot; yes, limited a little; and no, not limited at all). For the Patient-Reported Outcomes Measurement Information System (PROMIS) version, each item is rated on a 5-point scale (not at all, very little, somewhat, quite a lot, and cannot do). Recall period for items. Respondents are asked to rate limitation at present for most questions and over the past 4 weeks for other questions. Endorsements. None. Examples of use. The PF-10 was developed as a generic health outcome instrument within the SF-36 for a wide variety of medical conditions in people ages The PF-10 has been applied to older adult populations, as well as to people with rheumatoid arthritis (RA), back pain, osteoarthritis (OA), and gout (2). How to obtain. The PF-10 instrument, scoring manual, and license are available from QualityMetric at There is a charge at different rates for commercial and academic use. The PROMIS ver- S297

2 S298 White et al sion of the PF-10 is available for viewing at Method of administration. Interviewer (in person or by telephone) or self-administered. Scoring. Answers to each question are summed to produce raw scores and then transformed to a scale. Score interpretation. Higher scores represent better health status. For the SF-36 version 2.0, the total PF-10 score is standardized to a mean of 50. Population norms are available for the US (3) and the UK (4,5). World data for cross-cultural comparisons are available as well (6). Respondent burden. Less than 10 minutes is needed to complete the instrument. Questions are worded at a sixthto ninth-grade level. Administrative burden. Less than 10 minutes is necessary to administer the instrument and a few minutes are needed to score the results via computer. No training is required. Translations/adaptations. There are 2 versions of the PF-10: the original SF-36 version 1.0 and the updated SF-36 version 2.0. Most recently, the PROMIS created a 10-item physical functioning scale that has 5 of the same questions as the PF-10 versions pertaining to vigorous activities and basic mobility, and 5 questions pertaining to basic and instrumental activities of daily living (7). However, this review will focus on the SF-36 versions 1.0 and 2.0. The SF-36 versions of the PF-10 are available in more than 50 different languages. More information on the availability of the PF-10 in other languages can be found from the International Quality of Life Assessment project at Method of development. PF-10 questions were selected to assess a variety of physical activities ranging from easy to strenuous. The questionnaire was first examined in a group of subjects participating in the Medical Outcomes Study (8). Acceptability. Missing data are not common. The PF-10 was designed to have low ceiling and floor effects. Reliability. High test retest reliability has been found in people with RA (intraclass correlation coefficient [ICC] 0.93) (9) and low back pain (ICC ) (10). High internal consistency has also been reported for older adults (Cronbach s 0.82) (11) and people with gout (Cronbach s 0.93) (12). Validity. Criterion validity. The PF-10 has been found to be associated with both generic and disease-specific measures of functional outcome in a variety of rheumatologic patient populations. For subjects with hip or knee OA, Salaffi and colleagues reported a high correlation between the PF-10 and the Western Ontario and McMaster Universities Arthritis Index physical function subscale (r 0.65) (13). Similarly, a moderate correlation between the PF-10 and the Timed Up and Go Test was reported in subjects following total hip or knee replacement (r 0.34) (14). For people from Norway with RA, the PF-10 has been found to have strong correlations with the Modified Health Assessment Questionnaire (r 0.69) and the Arthritis Impact Measurement Scale physical domain (r 0.73) (15). Lastly, the PF-10 has been shown to be highly correlated with the Late Life Function and Disability Index in older adults (r ) (2). Construct validity. The PF-10 has been found to measure a single or unidimensional index in subjects with chronic medical and psychiatric conditions from the US (16), and in people with psoriatic arthritis (17). The PF-10 was also found to measure a unidimensional index among subjects from the general population from 7 countries, including Denmark, Germany, Italy, the US, Sweden, The Netherlands, and the UK (18). Ability to detect change. The PF-10 has been found to be a sensitive and responsive instrument to change in subjects with RA (9,19), spine pathology (10,20,21), and chronic medical and psychiatric diseases (22). In particular, the PF-10 was able to discriminate between groups of people with RA at different levels of improvement measured by the American College of Rheumatology criteria following a drug trial (19). Similarly, the PF-10 was sensitive to change in people with spine pathology undergoing physical therapy (10). Lastly, using data from subjects with chronic disease within the Medical Outcomes Study, McHorney and colleagues reported that the PF-10 had similar sensitivity to change regardless whether scores were Rasch-transformed or not (22). The minimum clinically important difference (MCID) for the PF-10 has been examined in subjects with spine pathology, specifically intervertebral disc herniation. In this patient population, the MCID is reported as ranging between 5 and 30 for the PF-10 (20). Strengths. The PF-10 is an important instrument of general physical function relevant to the rheumatology community. It evaluates limitations in function common in people with rheumatology-related disease and can be used to evaluate changes following intervention, especially in people with RA and spine pathology. Caveats and cautions. The psychometrics for the PF-10 have not been consistently investigated across all rheumatologic conditions. For instance, more work is needed to establish MCID thresholds for the PF-10 in people with RA. Clinical usability. The psychometric evaluation of the PF-10 does support interpretation of scores for individual patients and can be employed in the clinic given the short administration time. Research usability. The psychometric evaluation of the PF-10 does support use in intervention studies and observational studies. HEALTH ASSESSMENT QUESTIONNAIRE (HAQ) Purpose. This review focuses on the HAQ disability index with an emphasis on the use of the HAQ as a measure of general function (23). The HAQ measures difficulty

3 Adult General Function Status Measures S299 in performing activities of daily living. It is the most widely used functional measure in rheumatology. The HAQ was specifically developed for use among adults with arthritis, but it has since been used in a wide range of populations (24). Content. Questions assessing difficulty over the past week in 20 specific functions that are grouped into 8 categories: dressing and grooming, arising, eating, walking, personal hygiene, reaching, gripping, and other activities. Number of items. There are 20 items covering 8 subscales: dressing and grooming (2 items: dress yourself, including tying shoelaces and fastening buttons, and shampoo your hair); arising (2 items: stand up straight from an armless straight chair, get in and out of bed); eating (3 items: cut your meat, lift a full cup or glass to your mouth, open a new milk carton); walking (2 items: walk outdoors on flat ground, climb up 5 steps); personal hygiene (3 items: wash and dry your entire body, take a tub bath, get on and off the toilet); reaching (2 items: reach and get down a 5-pound object from just above your head, bend down to pick up clothing from the floor); gripping (3 items: open car doors, open jars that have been previously opened, turn faucets on and off); and other activities (3 items: run errands and shop, get in and out of a car, do chores such as vacuuming or yard work). In addition, the use of personal assistance, assistive aids, or devices is measured. Response options/scale. Each item is rated from 0 3, where 0 no difficulty, 1 some difficulty, 2 much difficulty, and 3 unable to do. The highest score within a category is used as the category score. Dependence on physical assistance or equipment raises the category score to 2. The HAQ score is calculated as the mean of the 8 category scores. Scores range from 0 3 in increments of The overall score is not calculated if fewer than 6 category scores are completed. Recall period for items. The past week. Endorsements. None. Examples of use. The HAQ was developed for individuals with rheumatoid arthritis (RA) and osteoarthritis (OA). How to obtain. The English version of the HAQ and the Patient-Reported Outcomes Measurement Information System (PROMIS) HAQ and scoring directions are provided free of charge at Method of administration. Interviewer (in person or by telephone) or self-administered (paper or electronic touchscreen version). The touch-screen version is self-explanatory and accessible for people with reduced motor function (25). Scoring. The HAQ is hand scored. Alternate methods of scoring have been developed (for example, scoring without taking use of assistance or aids into account [26] or using the mean category score instead of the highest score [27]), but these scoring methods have not gained wide use. Wolfe suggests that even if alternative scoring methods are used, the traditional score should also be calculated in order to be compare with published data (28). Score interpretation. Higher scores reflect more activity limitation. The overall estimated normal HAQ score was 0.25, with an average of 0.18 for males and 0.28 for females within a general population sample of 1,530 of people age 30 years in Central Finland (29). Approximately onethird of the respondents reported some sort of disability (HAQ 0). The prevalence of rates of disability increase exponentially after age 50 years (29). Respondent burden. Less than 10 minutes are needed to complete the HAQ. Questions are worded at a sixth- to ninth-grade level. Administrative burden. Less than 10 minutes are needed to administer the HAQ, and less than 2 minutes are needed to score the HAQ. No training is necessary. Translations/adaptations. Many adaptations and/or translations are available, including English (US, Canada, Australia), Belgian Flemish and French, Canadian French, Chinese (Cantonese, Hong Kong), Danish, French, German, Spanish (US, Spain, many Central and South American countries), Swedish, and Turkish. For a complete listing, see Bruce and Fries (30). A revised version of the HAQ, the HAQ-II, has been developed and contains 10 items (31). A PROMIS HAQ has been developed, which contains the same 20 items as the original HAQ, but they were qualitatively improved to increase the clarity and psychometric properties of the measure (32). Method of development. The HAQ was originally developed by using questions from a variety of instruments employed in the 1970s (23). Acceptability. Missing data are not common. The HAQ has ceiling limitations, i.e., people with mild functional limitation can have normal HAQ scores. Reliability. High test retest reliability has been found in subjects with gout. Specifically, the test retest reliability of the entire HAQ was intraclass correlation coefficient (ICC) 0.76, with individual subscales ranging from ICC 0.68 to ICC 0.80 (33). High correlations between interviewer versus self-administered forms of the instrument have been reported (range ) (24), as well as between a touch-screen and paper version (ICC 0.99) (25). Validity. For criterion validity, Daltroy et al (34) found a strong correlation ( 0.72) between HAQ scores and a physical capacity measure in older adults. For construct validity, HAQ scores are comparable across people with RA, OA, or gout using item response theory, which suggests the HAQ measures a single underlying construct of disability (35). Several studies have shown significant correlations of HAQ scores with other measures of function (e.g., Arthritis Impact Measurement Scale and Western Ontario and McMaster Universities Arthritis Index [WOMAC]) supporting the HAQ as a valid measure of general function (30,36 38). Ability to detect change. The HAQ is a sensitive and responsive measure to changes in function in people with knee or hip OA. For people undergoing hip or knee joint replacement, the HAQ is responsive to functional change

4 S300 White et al following surgery (39). Similarly, the HAQ has been found to be more sensitive to change over 3 years in people with hip or knee OA than the WOMAC (38). The HAQ has been found to have a ceiling effect, i.e., it does not discriminate well between people with low levels of disability (31,40). The minimum clinically important difference (MCID) for the HAQ has been examined in a variety of rheumatologicrelated populations including RA, psoriatic arthritis, systemic lupus erythematosus, spondylarthropathies, and scleroderma. The range for MCID is 0.08 to 0.25 for improvement and 0.13 to 0.22 for decline (41 47). Several authors have commented that MCID values may depend on the severity of disability. Specifically, less change was needed to meet a meaningful threshold for improvement for people with low levels of disability compared with those with a high level of disability (41,43,46). Strengths. The HAQ measures important limitations in function relevant to many people with rheumatology-related disorders. Given that MCID values have been established for multiple rheumatologic populations, the HAQ is appropriate for evaluating interventions. It is notable that all studies investigating MCID reported a similar range of values, making the HAQ a useful measurement of function and change in function. Caveats and cautions. The reliability, validity, and responsiveness of the HAQ requires more investigation. Specifically, the psychometrics of the HAQ need to be established across more rheumatologic patient populations. Clinical investigators should be aware that the HAQ does have floor effects, and may be less responsive to change among individuals with low levels of disability. Clinical usability. The psychometric evaluation of the HAQ does support interpretation of scores for individual patients with moderate to severe disability and can be employed in the clinic given the short administration time. Research usability. The psychometric evaluation of the HAQ does support use in intervention studies and observational studies, although sensitivity to change will likely be limited in people with mild disability. MODIFIED HEALTH ASSESSMENT QUESTIONNAIRE (MHAQ) Purpose. The MHAQ is a modified version of the HAQ (48). Content. The number of specific activities queried is reduced from 20 to 8 (1 item is used from each of the 8 categories covered in the HAQ). The MHAQ has 4 subscales that assess degree of difficulty, satisfaction with function, change in function over the past 6 months, and perceived need for help with each activity. The degree of difficulty subscale is the most commonly used. Number of items. There are 8 items (dressing, arising, eating, walking, hygiene, reaching, gripping, and getting in and out of car) repeated in each of the 4 subscales. Response options/scale. For the difficulty subscale ( Are you able to...? ), the scale is 0 without any difficulty, 1 with some difficulty, 2 with much difficulty, and 3 unable to do. Any positive response regarding help or assistive devices raises the score to 2. For satisfaction ( How satisfied are you with your ability to...? ), 0 satisfied and 1 dissatisfied. For change in difficulty ( Compared to 6 months ago, how difficult is it now [this week] to...? ), 0 less difficult now, 1 no change, and 2 more difficult now. For need for help (Do you need help to...? ), 0 do not need help and 1 need help. Scale scores are the mean of the scores on the 8 items within the scale: difficulty 0 3, satisfaction 0 1, change in function 0 2, and need for help 0 1. Recall period for items. Up to 6 months. Endorsements. None. Examples of use. People with rheumatic conditions (48). How to obtain. Available in original reference (48). Method of administration. Interviewer or self-administered. Scoring. Arithmetic calculation by hand. Score interpretation. Higher scores reflect poorer health. Respondent burden. Less than 5 minutes are needed to complete the MHAQ. Questions are worded at a sixth- to ninth-grade level. Administrative burden. Less than 5 minutes are needed to administer the MHAQ, and less than 2 minutes are needed to score the MHAQ. No training is necessary. Translations/adaptations. Two subsequent versions of the HAQ have been developed, the Multidimensional Health Assessment Questionnaire (48), and the HAQ-II (31). Both instruments were developed to address ceiling problems associated with the MHAQ (40). Method of development. Questions from the MHAQ are directly from the HAQ. Acceptability. Missing data are not common. The MHAQ has floor limitations and ceiling limitations (48). Reliability. The test retest reliability for the difficulty scale over 1 month was reported as 0.91 (48). Validity. For concurrent validity for the difficulty scale, the MHAQ is highly correlated with the overall score of the HAQ (0.88), the Arthritis Impact Measurement Scale physical component (0.80), and the Short Form 36 physical function scale (0.71) in people with rheumatoid arthritis (40). Blalock and colleagues also examined the equivalency of the HAQ with the MHAQ, and found that although the scores were highly correlated, the MHAQ scores were consistently and significantly lower (indicating better function) than the HAQ score (49). Uhlig and coauthors also found large numerical differences in scores,

5 Adult General Function Status Measures S301 especially at higher disability levels (40). In every category, HAQ items chosen for the MHAQ had a lower mean than the MHAQ-excluded items (49). For construct validity for the difficulty scale, the MHAQ scores have been found to be associated with measures of physical performance (e.g., walk test, grip strength) (50). For construct validity for dissatisfaction with function scale, scores were incrementally greater (more dissatisfied) as difficulty in function increased (48). Ability to detect change. For the difficulty scale, Blalock and colleagues suggest that the MHAQ is relatively insensitive to low levels of disability, and because of its restricted range and skewed distribution, should be used with caution when the intent is to assess functional change (49). Uhlig et al also reported a considerable ceiling effect for the MHAQ (40). Stucki et al (scores 0.3 [51]) and Wolfe (scores 1.0 [28]) also noted clustering of scores at the low end of the scale. Ziebland et al found that the MHAQ change in difficulty scale was more sensitive to changes in clinical variables (i.e., correlated more highly with variables such as grip strength, pain, morning stiffness, and erythrocyte sedimentation rate) than a pre-post difference in the traditional HAQ score (52). Strengths. Similar to the HAQ, the MHAQ measures important limitations in function relevant to many people with rheumatology-related disorders. Given its abbreviated form, the MHAQ should be considered when the full version of the HAQ cannot be implemented due to time constraints. Caveats and cautions. The majority of psychometric analysis of the MHAQ has focused on the difficulty subscale, and has generally found that it appears to be less psychometrically sound than the HAQ. Blalock et al noted that scores on the MHAQ were consistently lower than those on the HAQ (49). Mean differences on the overall difficulty score were 0.67 lower using HAQ scores calculated with adjustment for help and/or assistive devices, and 0.52 lower using HAQ scores without such adjustments. The MHAQ does not make adjustments for use of help or assistive devices. Blalock also noted that while the HAQ scores were normally distributed across the scale s full possible range (0 3), MHAQ scores were not normally distributed and ranged only from Similar findings were also noted by Stucki et al (51) and Wolfe (28). The MHAQ also has a considerable ceiling effect, which is greater than that of the HAQ (40). There are conflicting reports about correlations between MHAQ scores and clinical and laboratory variables. Wolfe concluded that the advantages in the length of the MHAQ over the HAQ were offset by loss of sensitivity and responsiveness to change (28). Clinical usability. The psychometric evaluation of the MHAQ does support limited use in the clinic, however, floor and ceiling effects should be considered when interpreting scores. Research usability. Given the MHAQ s limited ability to detect change, research use is not recommended. KATZ INDEX OF INDEPENDENCE IN ACTIVITIES OF DAILY LIVING Purpose. To quantify independence in activities of daily living (ADL) across a wide range of patient populations (53). Content. Basic ADL (bathing, dressing, toileting, transfers, continence, and feeding). Katz et al noted that the loss of functional skills occurs in a specific order, with the most complex lost first (54). The scoring method for this scale reflects this hierarchy of function. Number of items. 6, 1 for each ADL. Response options/scale. Each ADL is scored on a 3-point scale of independence. Items are ordered by difficulty. The scoring reflects this, although some variation in the hierarchy of difficulty is allowed. Katz reported that ADL functions of 86% of evaluated subjects were consistent with the hierarchy (54). Score range is A G or 0 6. Recall period for items. Immediate. Endorsements. None. Examples of use. The Katz Index of ADL has been used in older adults (55), people with stroke (56), and older adults with hip fracture (57). How to obtain. Available from original reference (54) and at Method of administration. Examiner-administered via observation of the patient. Scoring. Independence in various combinations of ADL determines ordinal rank on the alpha scale, or the number of ADLs for which the individual is dependent for the numeric scale. Ratings are made are on an 8-level ordinal scale, where A independence in feeding, continence, transferring, going to toilet, dressing, and bathing; B independent in all but 1 of these functions; C independent in all but bathing and 1 additional function; D independent in all but bathing, dressing, and 1 additional function; E independent in all but bathing, dressing, going to toilet, and 1 additional function; F independent in all but bathing, dressing, going to toilet, transferring, and 1 additional function; G dependent in all 6 functions; and other dependent in at least 2 functions, but not classifiable as C, D, E, or F. Katz and Akpom later proposed a simplified scoring system in which individuals are scored 0 6, reflecting the number of ADLs in which they are dependent (58). Score interpretation. Scores reflect the specific ADLs or number of dependent ADLs. Higher (alphabetically or numerically) scores reflect greater independence. Respondent burden. Five minutes to complete. Instrument is performance based. Administrative burden. Must observe the patient in each ADL to determine level of independence. Translations/adaptations. The Katz Index of ADL has been adapted into several versions that are comparable to the original (59,60), while others have been modified

6 S302 White et al (61,62). The Katz Index of ADL has also been translated into Spanish (63). Research usability. Use of the Katz Index of ADL in research studies is not well supported. Method of development. The Katz Index of ADL was developed from the observations of inpatients with hip fractures. Observations were made by physicians, nurses, and other health professionals (54). Acceptability. The Katz Index of ADL measures only basic ADLs, and therefore has ceiling effects, i.e., the index cannot discriminate well among people with no and mild limitations. Reliability. The interrater reliability is 0.95 or better after training (54,64). The coefficient of reproducibility (a measure of the internal consistency of an ordered measure) is (65). In a study examining the reliability and validity of self-reported limitations in ADL among Turkish, Moroccan, and indigenous Dutch elderly in The Netherlands, Reijneveld et al reported that internal consistency reliabilities were good for all ethnic groups, being slightly higher for Turkish and Moroccan elderly people than for Dutch elderly (66). Validity. Regarding construct validity, the Katz Index of ADL is associated with scores from the Barthel Index (r 0.78 [67], 0.77 [68]). The Spanish versions of the Katz Index of ADL are associated with mortality, institutionalization, and utilization of social health services (63). For predictive validity, the Katz Index of ADL is associated with mobility dysfunction (0.50) and house confinement (0.39) among older patients 2 years later (69). There is also a correlation between ADL dependency level and mortality among nursing home residents (64). Comparing patients at 1-month poststroke, those with grade A-B-C at admission were more likely to go home compared with those with a grade of D-E-F-G (56). Ability to detect change. The scale had a significant floor effect, in that it is relatively insensitive to variations at low levels of disability (36). Scores on the Katz ADL scale are dependent on the physical environment, i.e., different scores may be obtained for individuals in different settings or with different environmental modifications (37). Strengths. The Katz Index of ADL measures important functional limitations, which can occur in rheumatologic patient populations. Caveats and cautions. There has been little investigation of sensitivity and responsiveness of the Katz Index of ADL. Most problematic is potential for ceiling effects with people with mild limitations in ADLs. This could lead to the index not being responsive to changes in ADLs in people with low levels of disability. Clinical usability. The psychometric evaluation provides some support for the clinical use of the Katz Index of ADL, however, more robust measures of ADL function, such as the Functional Independence Measure should be considered. FUNCTIONAL INDEPENDENCE MEASURE (FIM) Purpose. The FIM estimates the level of assistance needed for patients to complete basic activities of daily living (ADL) (70). The FIM was designed to be an assessment tool that could be implemented universally across all patient populations within an inpatient rehabilitation hospital environment (70). Content. The FIM includes 18 basic ADLs, such as selfcare, sphincter control, transfers, locomotion, communication, and social cognition. Clinicians score patients on a 7-point scale ranging from dependent to independent, which reflects the level of assistance needed to complete each ADL. Number of items. The FIM items are organized into the motor and cognitive domains, which are further organized into 4 subscales for the motor domain and 2 subscales for the cognitive domain. Response options/scale. A trained health professional rates a patient on a scale of 1 7, where 1 total assistance (the patient provides 25% effort to complete each task), 2 maximal assistance (25 49% effort), 3 moderate assistance (50 74% effort), 4 minimal assistance ( 75% effort), 5 supervision/set up (need for supervision but no physical contact), 6 modified independence (use of a device or need for more than a reasonable time to complete each task), and 7 complete independence (the patient completes each task in a timely and safe manner). Different health professionals can score sections specific to their discipline. For instance, a physical therapist can score the mobility-related items for a patient while an occupational therapist scores the ADL-related items. There are 2 gross score classifications: dependent (helper: scores 1 5) and independent (no helper: scores 6 7). The total FIM score is calculated by summing the score of each of the 18 items. Recall period for items. Immediate. Endorsements. The FIM is used to determine payment for inpatient acute rehabilitation services from the Centers for Medicare and Medicaid Services. In particular, the FIM is used to determine coverage for patients under Medicare Part A. Examples of use. Individuals within the inpatient acute rehabilitation hospital setting. How to obtain. The FIM System program is available at A sample of the FIM instrument can be found at br.fcgi?book physmedrehab&part A11332&rendertype figure&id A Method of administration. Observation by members of an interdisciplinary team. Scoring. Specific scoring instructions apply to the FIM. Training manuals for scoring are available from the Cen-

7 Adult General Function Status Measures S303 ters from Medicare and Medicaid Services, cms.gov/inpatientrehabfacpps/04_irfpai.asp. Score interpretation. Scores range from Higher scores represent more independence. A score of 18 represents complete dependence, while a score of 126 represents complete independence. The total FIM score is appropriate to report if the goal of assessment is to determine the overall burden of care (71). There are 2 domains of the FIM: motor and cognitive. The motor domain subscales include self-care (6 items: eating, grooming, bathing, dressing upper body, dressing lower body, and toileting); sphincter control (2 items: bladder management, bowel management); transfers (3 items: bed/chair/wheelchair, toilet, tub/shower); and locomotion (2 items: walk or wheelchair, stairs). The motor domain was developed from the Barthel Index (72). The cognitive domain subscales include communication (2 items: comprehension, expression) and social cognition (3 items: social interaction, problem solving, memory). The mean SD admission FIM total was and discharge FIM total was for patients with lower extremity joint replacement who were discharged from a rehabilitation program in 2007 (73). Respondent burden minutes to perform all activities. Patients are asked to perform each functional task in order to generate a score, which may be difficult. Administrative burden. 7 minutes to collect demographic data and 10 minutes to score. Formal training is needed to administer the FIM. A training examination is available at: Translations/adaptations. The FIM has been translated into different languages including Italian and Turkish (74,75). Method of development. The FIM was created to provide an improvement over the Barthel Index. It has been developed and tested mainly in people with neurologic pathology. Acceptability. Missing data are not common. The instrument has some ceiling effects within each of the motor and cognitive domains. Reliability. High reliability has been reported for the FIM. In a quantitative review of 11 studies, Ottenbacher et al reported high interrater and test retest reliability for health professionals with a variety of educational backgrounds and levels of training (76). Based on 1,568 patients with a variety of medical diagnoses, the median interrater reliability was 0.95 and test retest reliability was Median reliability for the 6 subscales ranged from 0.78 (social cognition) to 0.95 (self-care), and the 18 individual items ranged from 0.61 (comprehension) to 0.90 (toilet transfer). Pollak and colleagues also found high test retest reliability for the motor (intraclass correlation coefficient [ICC] 0.90) and cognitive domains (ICC 0.80) in a cohort of older adults age 80 years residing in a multilevel retirement community (77). High internal consistency was found for the total FIM score (Cronbach s ) (71,78), the motor domain ( ) (71,79), and the cognitive domain ( ) (71) within a large sample of inpatients undergoing acute rehabilitation with various diagnoses. However, lower internal consistency was reported for the locomotion subscale ( 0.68), suggesting that the individual items (ambulation/wheelchair use and stair climbing) may be measuring a different latent construct of function (78). Internal consistency was also high for FIM scores obtained via interview ( 0.94) or observation ( 0.90) (80). Validity. Regarding concurrent validity, FIM scores assigned by a single nonclinician interview and by observation by a team of health care professionals were similar (ICC 0.74 for admission FIM and ICC 0.76 for discharge FIM), which provides evidence that a multi-interviewer administered FIM is a valid method for collecting data (81). For construct validity, the separation of the FIM into motor and cognitive domains has been found to be a valid method of measuring activity limitation (82 84). The items in each domain show a generally consistent pattern of difficulty rating across multiple medical diagnoses, with eating the least difficult motor item to achieve an independent rating, and stair climbing the most difficult (82 84). For cognitive items, expression is the least difficult and problem solving is the most difficult (82,84). FIM scores are correlated with age, comorbidity, and discharge destination (78), as well as other functional measures, such as the Barthel Index and the Functional Assessment Measure (79,80,85,86). While little work has examined the predictive validity of the FIM within rheumatologic patient populations, several studies have examined this within stroke. Trends from these studies can be carefully considered for patients with rheumatologic conditions who are at an inpatient rehabilitation hospital. Admission FIM scores have been shown to predict length of stay and discharge FIM scores in a rehabilitation hospital following stroke (80,87 91). In particular, an increase in the admission score of the motor domain by 1 point is correlated with a 1.1-day decrease in average rehabilitation length of stay for patients with stroke (87). There is a strong association between total FIM scores and discharge destination, i.e., discharge home versus skilled nursing facility (90,92 95). A majority of patients with stroke with admission FIM scores 80 are discharged home, while less than half with admission FIM scores 40 are discharged home, regardless of age (94). Social support has been shown to be a decisive factor for discharge destination, especially for those requiring high levels of assistance (90,93). Ability to detect change. The FIM, especially the motor FIM, is highly responsive in detecting changes in ADL performance (78,80,96), but the cognitive FIM has a poor responsiveness due to its significant ceiling effect seen across a wide variety of medical diagnoses (96 99). There is comparable responsiveness between the FIM and the Barthel Index (79,80,85,96,100). Beninato et al reported a minimum clinically important difference for the total FIM of 22, the motor FIM of 17, and the cognitive FIM of 3 in the stroke population when anchored to a physician s assessment of minimally clinically important change (101).

8 S304 White et al Strengths. The FIM is a widely used tool in the rehabilitation setting across a broad range of medical diagnoses including rheumatologic diagnoses. The FIM is appropriate for evaluating interventions for people with severe functional limitation. Caveats and cautions. The FIM is not intended for community-dwelling adults who are independent in most functional activities. Future work is needed to validate the predictive validity of the FIM within rheumatologic patient populations. Clinical usability. The psychometric evaluation does support interpretation of scores for individuals with severe functional limitation. Clinical use is primarily done in an inpatient acute rehabilitation setting. Research usability. The psychometric evaluation does support use of the FIM within intervention studies and observational studies. OSTEOARTHRITIS-FUNCTION-COMPUTER ADAPTIVE TEST (OA-FUNCTION-CAT) Purpose. The OA-FUNCTION-CAT employs computer adaptive testing to estimate a respondent s level of functioning. It was developed as a disease-specific measure for people with hip or knee OA (102). Content. The OA-FUNCTION-CAT utilizes an item bank of 125 functional activities specific to hip or knee OA. Number of items in scale. The OA-FUNCTION-CAT selects 5, 10, or 15 items from the 125-item bank for administration. Recall period for items. Over the past month on an average day. Endorsements. None. Examples of use. The OA-Function-CAT was developed in a hip and knee OA cohort of subjects (102). How to obtain. Contact CREcare ( com/home.html) regarding cost and availability of the instrument. The 125-item bank is available for no fee at S1.doc. Method of administration. A CAT tailors assessment to each individual by selecting and administering subsequent questions based on the individual s response to the previous question. The program begins by selecting a question from the middle of the continuum of the calibrated item bank. Based on how the respondent answers the question, the computer calculates an initial score and level of precision. The CAT will conclude the test based on predetermined stop rules based on level of precision and/or a maximum number of items that are to be used to estimate the score. After the first question is answered, the program decides if the stop rule has been met. If not, another question is selected from the item bank based on the answer given for the previous question. This process is repeated until the stop rule has been satisfied, and a final score is calculated. This approach allows for the selection of items that provide the most relevant information at the level of the individual s current score estimate, therefore eliminating irrelevant questions from being asked ( ). Scoring. Continuous scale. For the functional difficulty scale, items are reported in terms of amount of difficulty in performing each function (none, a little, or a lot). For the functional pain scale, items are reported in terms of pain severity in performing each function (none, mild or moderate, or severe). The computer automatically calculates an outcome score representing how much limitation the individual has within the spectrum of functional limitation. This score is based on the individual s response to each of the questions asked. Interpretation of scores. Scores range from Higher scores represent higher function and less pain. The score produced on the CAT can be compared to other OA-FUNCTION-CAT scores regardless of the specific questions that were asked to generate the score. The OA- FUNCTION-CAT calculates a functional outcome score that can be compared within and between respondents. Respondent burden. 15 or fewer questions are asked (questions written on a sixth-grade level of comprehension). Administrative burden. Minimal burden since the computer program calculates the score in real time, so the score is available immediately. Translations/adaptations. None. Training to interpret. Not reported. Reliability. There is high level of accuracy between the 5-, 10-, and 15-item OA-FUNCTION-CATs and the full item bank (Pearson s r 0.92, 0.96, and 0.97, respectively, for the functional difficulty subscale and 0.89, 0.95, and 0.97, respectively, for the functional pain subscale) among people with hip or knee OA. There is high conditional reliability, i.e., examinee level reliability (105), for both the functional difficulty and functional pain subscales (95% of the sample scores achieved reliability estimates 0.97 and 0.96, respectively) (102). Validity. Regarding construct validity, both the functional difficulty and functional domain subgroups fit a unidimensional model. Both of the OA-FUNCTION-CAT subscales cover a broader estimated scoring range than the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), especially at the upper, i.e., higher functioning, end of the scale. The OA-FUNCTION-CAT had less of a ceiling effect than the WOMAC (0.6% of subjects were at the ceiling for the OA-FUNCTION-CAT functional pain subscale versus 6.4% for the WOMAC pain scale, and 0.6% of subjects were at the ceiling for the OA-FUNC- TION-CAT functional difficulty subscale versus 3.0% for the WOMAC physical function scale). The OA-FUNC- TION-CAT did not have a floor effect (102).

9 Adult General Function Status Measures S305 Ability to detect change. The 10-item OA-FUNCTION- CAT has a higher degree of precision than the WOMAC across the full range of scores for both subscales, especially at the upper end of the scale in the functional pain subscale within people with hip or knee OA (102). Strengths. The OA-FUNCTION-CAT is an innovative method of measuring patient reported outcomes relevant to people with rheumatologic related disorders. The OA- FUNCTION-CAT has improved psychometric properties and requires fewer questions compared with legacy measures. Specifically, CATs offer a highly reliable and precise method to quantify patient reported limitations along a broad continuum. In addition, CAT scores can be estimated after only a few questions are answered, which decreases overall time and cost of administration. Caveats and cautions. Future work is needed to examine the test retest reliability of the OA-FUNCTION-CAT; utilization of CAT methods for estimating patient-reported outcomes is likely to increase among clinicians and researchers. Clinical usability. The psychometric evaluation of the OA-FUNCTION-CAT supports interpretation of scores to make decisions about individuals. Given the minimal burden on patients and clinicians, the OA-FUNCTION-CAT is very appropriate to use clinically. Research usability. The OA-FUNCTION-CAT can be used within intervention trials and observational studies given the psychometrics of this instrument. Values representing meaningful change have yet to be established which may limit clinical and research application. AUTHOR CONTRIBUTIONS All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. REFERENCES 1. Ware JE Jr, Sherbourne CD. 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