Can the ABILHAND handle manual ability in MS?

BACKGROUND: Hand dysfunction is common in multiple sclerosis (MS). Recent interest has focused on incorporating patient-reported outcome (PRO) instruments into clinical trials. Nevertheless, examinations are rare in MS of existing manual ability measures. OBJECTIVES: The objective of this paper is to evaluate the 23-item ABILHAND, developed for use after stroke, in people with MS, comparing the findings from two psychometric approaches. METHODS: We analysed ABILHAND data from 300 people with MS using: 1) traditional psychometric methods (data completeness, scaling assumptions, reliability, internal and external construct validity); and 2) Rasch measurement methods (including targeting, item response category ordering, data fit to the Rasch model, spread of item locations, item scoring bias, item stability, reliability, person response validity). RESULTS: Traditional psychometric methods implied ABILHAND was reliable and valid in this sample. Rasch measurement methods supported this finding. The three-category scoring function worked as intended and item fit to Rasch model expectations was acceptable. The 23 items (location range -3.16 to +2.73 logits) mapped a continuum of manual ability. Reliability was high (Person Separation Index (PSI) = 0.95). CONCLUSION: Both psychometric evaluations supported ABILHAND as a robust manual ability PRO measure for MS. Rasch measurement methods were more informative and, consistent with its role of detecting anomalies, identified ways of advancing further ABILHAND's measurement performance to reduce any potential for type II errors in clinical trials.

Beyond the reach of traditional analyses: using Rasch to evaluate the DASH in people with multiple sclerosis.

BACKGROUND: Few upper limb functioning patient rating scales have been used in multiple sclerosis (MS) research and none developed specifically for people with MS. OBJECTIVES: In this study, we examined the Disabilities of the Arm, Shoulder and Hand (DASH) to determine its utility as a useful, scientifically robust and clinically meaningful tool in MS. METHODS: DASH data from 300 people with MS underwent two independent phases of psychometric analyses: (1) a traditional psychometric analysis (including data quality, scaling assumptions, reliability and validity); and (2) a Rasch analysis (including response option thresholds ordering, tests of fit, spread of item locations, residual correlations, and person separation index). RESULTS: Overall, the traditional psychometric analysis supported the DASH as a reliable and valid measure of upper limb function in people with MS. However, several issues were raised by the Rasch analysis that questioned the validity of the DASH, including misfit in 13/30 items, disordered item response option thresholds for 9/30 items, and six pairs of items with high residual correlations (> 0.60). CONCLUSION: Rasch analysis highlights areas for potential improvement for the use of the DASH. Our findings further support our previous arguments that traditional psychometric methods provide weak scale evaluations and can mislead clinicians as to the reliability and validity of outcome measures.

CDIP-58 can measure the impact of botulinum toxin treatment in cervical dystonia.

We compared the responsiveness of the Cervical Dystonia Impact Profile (CDIP-58), Medical Outcome Study Short Form-Health Survey (SF-36), Functional Disability Questionnaire (FDQ), and Pain and Activities of Daily Living subscales of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) in participants with cervical dystonia treated with botulinum toxin A. Subscales of CDIP-58 were more sensitive in detecting statistical and clinical change than comparable subscales of the SF-36, FDQ, and TWSTRS.

Exploring disability rating scale responsiveness II: do more response options help?

The Barthel Index (BI) may underestimate disability change because its items have few response options. We examined whether a similar scale with more response options (Functional Independence Measure, FIM) was more responsive (n = 1,396). The FIM had greater potential for responsiveness and identified more people who changed. However, its actual responsiveness, measured by effect sizes, equaled that of the BI. This counterintuitive finding suggests that effect sizes may be limited indicators of responsiveness.

Talking the talk on walking the walk: a 12-item generic walking scale suitable for neurological conditions?

BACKGROUND: The Multiple Sclerosis Walking Scale (MSWS-12) was developed to measure the impact of multiple sclerosis on walking. Many other disabling neurological conditions affect patients' ability to walk, and a generic measure of walking could provide valuable insights into patients' perceptions in clinical trials and epidemiological studies as well as routine clinical practice. OBJECTIVE: To evaluate the clinical usefulness and psychometric properties of the Walking Impact Scale (Walk-12), a modified version of the MSWS-12, in patients with neurological conditions. DESIGN: A prospective, observational study of 120 consecutive patients admitted for rehabilitation. The Walk-12 was used to measure the impact of neurological disability on walking. Traditional psychometric methods (data quality, scaling assumptions, targeting, reliability, validity and responsiveness) were used to assess the Walk-12. Transition questions were used on discharge to measure perception of change. Outcome was also measured using the timed walk test (TWT), Barthel Index (BI) and Functional Independence Measure (FIM). RESULTS: For the total group, missing data were few, scaling assumptions were satisfied, and internal consistency was 0.94. Correlations between the Walk-12 and TWT, BI and FIM motor score were moderate (r=-0.58, -0.26, -0.31). Responsiveness of the Walk-12 was high (effect size=1.12). Relationships between effect size and patients' and physiotherapists' opinion of change in walking demonstrated good concordance. Preliminary subgroup analyses indicate satisfactory psychometric properties across different neurological conditions; however, sample numbers in these analyses are small. CONCLUSIONS: In this sample of neurologically disabled patients the Walk-12 was clinically useful and satisfied standard psychometric criteria. This provides preliminary evidence that it may be suitable as a generic measure of walking ability.

Proxy measurements in multiple sclerosis: agreement between patients and their partners on the impact of multiple sclerosis in daily life.

BACKGROUND: The use of self-report measurements in clinical settings has increased. The underlying assumption for self-report measurements is that the patient understands the questions fully and is able to give a reliable assessment of his or her own health status. This might be problematic in patients with limitations that interfere with reliable self-assessment such as cognitive impairment or serious mood disturbances, as may be the case in multiple sclerosis. In these situations proxies may provide valuable information, provided we can be certain that proxies and patients give consistent ratings. OBJECTIVE: To examine whether patients with multiple sclerosis and their partners agree on the impact of multiple sclerosis on the daily life of the patient by using the Multiple Sclerosis Impact Scale (MSIS-29). METHODS: 59 patients with multiple sclerosis and their partners completed the MSIS-29. Agreement was examined, comprehensively at scale score levels and item functioning, using both traditional and less conventional psychometric methods (Rasch analysis). RESULTS: Agreement between patients and partners was good for the physical scale, and slightly less but still adequate for the psychological scale. Mean directional differences did not show considerable systematic bias between patients and proxies. Intraclass correlation coefficients (ICCs) satisfied the requirements for agreement, but were higher for the physical scale (0.81) than for the psychological scale (0.72). These findings were supported by Rasch analyses. CONCLUSION: In this sample, albeit small, partners provided accurate estimates of the impact of multiple sclerosis. This supports the value of self-rating scales and indicates that partners might be useful sources of information when assessing the impact of multiple sclerosis on the daily life of patients.

Getting the measure of spasticity in multiple sclerosis: the Multiple Sclerosis Spasticity Scale (MSSS-88).

Spasticity is most commonly defined as an inappropriate, velocity dependent, increase in muscle tonic stretch reflexes, due to the amplified reactivity of motor segments to sensory input. It forms one component of the upper motor neuron syndrome and often leads to muscle stiffness and disability. Spasticity can, therefore, be measured through electrophysiological, biomechanical and clinical evaluation, the last most commonly using the Ashworth scale. None of these techniques incorporate the patient experience of spasticity, nor how it affects people's daily lives. Consequently, we set out to construct a rating scale to quantify the perspectives of the impact of spasticity on people with multiple sclerosis. Qualitative methods (in-depth patient interviews and focus groups, expert opinion and literature review) were used to develop a conceptual framework of spasticity impact, and to generate a pool of items with the potential to convert this framework into a rating scale with multiple dimensions. This item pool was administered, in the form of a questionnaire, to a sample of people with multiple sclerosis and spasticity. Guided by Rasch analysis, we constructed and validated a rating scale for each component of the conceptual framework. Decisions regarding item selection were based on the integration and assimilation of seven specific analyses including clinical meaning, ordering of thresholds, fit statistics and differential item functioning. The qualitative phase (17 patient interviews, 3 focus groups) generated 144 potential scale items and a conceptual model with eight components addressing symptoms (muscle stiffness, pain and discomfort and muscle spasms,), physical impact (activities of daily living, walking and body movements) and psychosocial impact (emotional health, social functioning). The first postal survey was sent to 272 people with multiple sclerosis and had a response rate of 88%. Findings supported the development of scales for each component but demonstrated that five item response options were too many. The 144-item questionnaire, reformatted with four-item response options, was administered with four validating instruments to an independent sample of 259 people with multiple sclerosis (response rate 78%). From the responses, an 88-item instrument with eight subscales was developed that satisfied criteria for reliable and valid measurement. Correlations with other measures were consistent with predictions. The 88-item Multiple Sclerosis Spasticity Scale (MSSS-88) is a reliable and valid, patient-based, interval-level measure of the impact of spasticity in multiple sclerosis. It has the potential to advance outcomes measurement in clinical trials and clinical practice, and provides a new perspective in the clinical evaluation of spasticity.

Measuring quality of life in multiple sclerosis: not as simple as it sounds.

Data from a clinical study presented an opportunity to examine the psychometric properties of the Leeds Multiple Sclerosis Quality of Life scale (LMSQoL), which has undergone limited psychometric evaluation. LMSQoL and Multiple Sclerosis Quality of Life-54 (MSQoL-54) data were collected from 90 people with multiple sclerosis (MS) living in the community. Standard psychometric methods to examine data quality, scaling assumptions, scale to sample targeting, reliability, validity, and responsiveness were employed. The LMSQoL satisfied criteria for data quality (no missing data), scaling assumptions (item-total correlations: 0.24-0.56), reliability (Cronbach's alpha: 0.71), and demonstrated responsiveness (effect size: 0.34). Correlations between the LMSQoL and MSQoL-54 physical (range: -0.02 to -0.50) and emotional subscales (range: -0.38 to -0.65) were similar; the magnitude and pattern was not consistent with predictions based on the construct purported to be measured by the LMSQoL. The LMSQoL satisfied many psychometric criteria in this small study, however, it was difficult to interpret the validity data. From this, two fundamental measurement issues are highlighted. Firstly, current methods of examining rating scales provide only circumstantial evidence of validity; secondly, health-rating scales should be developed on the basis of clear conceptual definitions.

How responsive is the Multiple Sclerosis Impact Scale (MSIS-29)? A comparison with some other self report scales.

OBJECTIVES: To compare the responsiveness of the Multiple Sclerosis Impact Scale (MSIS-29) with other self report scales in three multiple sclerosis (MS) samples using a range of methods. To estimate the impact on clinical trials of differing scale responsiveness. METHODS: We studied three discrete MS samples: consecutive admissions for rehabilitation; consecutive admissions for steroid treatment of relapses; and a cohort with primary progressive MS (PPMS). All patients completed four scales at two time points: MSIS-29; Short Form 36 (SF-36); Functional Assessment of MS (FAMS); and General Health Questionnaire (GHQ-12). We determined: (1) the responsiveness of each scale in each sample (effect sizes): (2) the relative responsiveness of competing scales within each sample (relative efficiency): (3) the differential responsiveness of competing scales across the three samples (relative precision); and (4) the implications for clinical trials (samples size estimates scales to produce the same effect size). RESULTS: We studied 245 people (64 rehabilitation; 77 steroids; 104 PPMS). The most responsive physical and psychological scales in both rehabilitation and steroids samples were the MSIS-29 physical scale and the GHQ-12. However, the relative ability of different scales to detect change in the two samples was variable. Differing responsiveness implied more than a twofold impact on sample size estimates. CONCLUSIONS: The MSIS-29 was the most responsive physical and second most responsive psychological scale. Scale responsiveness differs notably within and across samples, which affects sample size calculations. Results of clinical trials are scale dependent.

Evaluating neurorehabilitation: lessons from routine data collection.

BACKGROUND: Clinical databases are being used increasingly to assess outcomes in healthcare services to provide evidence of clinical effectiveness in routine clinical practice. OBJECTIVES: To explore the benefits of a database for routine collection of clinical outcomes within an inpatient neurorehabilitation setting; determine the effectiveness of inpatient neurorehabilitation in a range of neurological conditions; and determine variables influencing change in functional outcome. METHODS: Over a nine year period, demographic and diagnostic characteristics were collected for the 1458 patients admitted consecutively to a neurorehabilitation unit. The level of function was measured on admission and discharge using the Barthel Index (BI) and Functional Independence Measure (FIM). Patient perception of rehabilitation benefit was evaluated using visual analogue scales (VAS). RESULTS: Of the 1413 patients (mean (SD) age 48 (14.8), range 16 to 87) whose length of stay was more than 10 days (mean 34 (24) range 10 to 184), 282 had stroke, 614 multiple sclerosis, 248 spinal cord injuries, 93 a neuromuscular condition, and 176 other brain pathology. Patients improved in functional ability as measured by both BI and the FIM motor subscale (effect sizes 0.93 to 1.44 and 1.01 to 1.48, respectively). VAS ratings demonstrated high levels of patient perceived benefit. Diagnosis, functional activity score on admission, and length of stay were significant predictors of functional gain, explaining 44% of the variability in the change scores. CONCLUSIONS: Systematic collection, analysis, and interpretation of standardised clinical outcomes data are feasible within routine clinical practice, and provide evidence that inpatient rehabilitation is effective in improving functional level in neurologically impaired patients. These data complement those of clinical trials and are useful in informing and developing clinical and research practice.

Capturing the true burden of dystonia on patients: the Cervical Dystonia Impact Profile (CDIP-58).

OBJECTIVES: To develop a new rating scale for measuring the health impact of cervical dystonia (CD) that includes patients' perceptions and complements existing observer dependent clinician rating scales. METHODS: Scale development was in three stages. In Stage 1, a large pool of items was generated from patient interviews (n = 25), expert opinion, and literature review. In Stage 2, these items were administered by postal survey to people with CD. The resulting data were analyzed using Rasch item analysis to construct, from the item pool, a rating scale that satisfied criteria for rigorous measurement. In Stage 3, the measurement properties of this rating scale were examined in an independent sample of people with CD. RESULTS: In Stage 1, 150 items concerning the health impact of CD were generated. In Stage 2, 556 people completed questionnaires (87% response rate) and a 58-item rating scale measuring the health impact of CD in eight areas was constructed (CD Impact Profile, CDIP-58). In Stage 3, CDIP-58 data from 391 people (87% response rate) were received. Analyses supported the measurement of eight unidimensional constructs (infit mean square range 0.62 to 1.50), item calibration (33.37 to 67.56), and patient separation statistics (2.59 to 3.38). Items demonstrated stable calibrations in subgroups of people with CD supporting the stability of the CDIP-58. CONCLUSIONS: The CDIP-58 is a reliable and valid patient-based rating scale measuring the health impact of CD in eight health dimensions.

Self-efficacy predicts self-reported health status in multiple sclerosis.

Self-efficacy is a belief that one can competently cope with a challenging situation. If self-efficacy is a strong predictor of health status in multiple sclerosis (MS), it may be an important area to target in clinical practice, as such beliefs may be modifiable. The aim of this study was to examine the predictive value of self-efficacy on self-reported health status in MS. Eighty-nine people with MS completed the Multiple Sclerosis Self-efficacy Scale (MSSE function and control scales), the Multiple Sclerosis Impact Scale (MSIS-29), and the Multiple Sclerosis Walking Scale (MSWS-12) at two time points: 1) admission to an inpatient rehabilitation unit (n = 43) or for steroid treatment for relapses (n = 46); and 2) discharge (rehabilitation group) or six weeks later (steroid group). Multiple regression analyses examined whether baseline and changes in self-efficacy predict changes in self-reported health status. Both baseline and changes in self-efficacy were strong and independent predictors of changes in health status (P-values ranged from 0.025 to < 0.001). That is, pretreatment self-efficacy scores and increases in self-efficacy scores from baseline to follow-up (improvement), were significantly associated with decreases (improvement) in perceived walking ability and physical and psychological impact of MS. The findings suggest that self-efficacy predicts improvement in health status and that self-efficacy would be an important domain to measure and manage actively in education and rehabilitation programs.

Improving the evaluation of therapeutic interventions in multiple sclerosis: development of a patient-based measure of outcome.

OBJECTIVES: To develop a patient-based, disease-specific measure of the health impact of multiple sclerosis (MS) for use in clinical trials and clinical practice. DATA SOURCES: People with MS. Members of the MS Society of Great Britain and Northern Ireland. METHODS: Standard psychometric methods were used to develop the Multiple Sclerosis Impact Scale (MSIS-29) in three stages. Stage 1 (item generation): questionnaire items were generated from 30 patient interviews on the impact of MS on their lives, expert opinion and literature review. Stage 2 (item reduction and scale generation): the questionnaire developed in stage 1 was administered by postal survey to 1530 randomly selected members of the MS Society. Standard item reduction techniques were used to develop a rating scale from the pool of questionnaire items. Stage 3 (psychometric evaluation): the questionnaire was evaluated for data quality, scaling assumptions, acceptability, reliability and validity in a separate postal survey of 1250 MS Society members. Responsiveness was evaluated in 55 people admitted to hospital for rehabilitation and intravenous steroid treatment of MS relapses. RESULTS: Stage 1 resulted in a 129-item questionnaire. Stage 2 resulted in a 29-item rating scale measuring the physical and psychological impact of MS. The MSIS-29 satisfied all recommended psychometric criteria for rigorous measurement. Data quality was excellent: missing data were low, item test-retest reliability was high and scale scores could be generated for over 98% of respondents. Item descriptive statistics, item convergent and discriminant validity, and factor analysis supported summing items to produce two summary scores. MSIS-29 physical and psychological scale scores showed good variability, low floor and ceiling effects, good internal consistency and test-retest reliability. Correlations with other measures and confirmation of hypotheses about group differences provided evidence for the validity of the MSIS-29 as a measure of the physical and psychological impact of multiple sclerosis. Effect sizes provided preliminary evidence for responsiveness. CONCLUSIONS: The 29-item MSIS-29 is a rigorous new measure of the physical and psychological impact of MS. All psychometric criteria were satisfied and there is preliminary evidence of responsiveness. The MSIS-29 is particularly appropriate for use in clinical trials to evaluate therapeutic effectiveness from the patient's perspective. Further critical evaluations of the MSIS-29 completed by people with neurologist-confirmed MS in different settings are suggested. Head-to-head comparisons of the psychometric properties of the MSIS-29 and other outcome measures for MS will help to determine the relative advantages of different instruments so that the choice of measures for studies can be evidence based.

Evidence-based measurement in multiple sclerosis: the psychometric properties of the physical and psychological dimensions of three quality of life rating scales.

The selection of measures of quality of life used in clinical trials of multiple sclerosis (MS) should be evidence-based. Head-to-head comparison of measures facilitates the selection of measures. The aim of the study was to compare the psychometric properties of the physical and psychological dimensions in three measures of quality of life to aid choice of the most appropriate scale for use in clinical trials of MS. One hundred and twenty-one people with MS (rehabilitation = 57; steroids = 64) completed a selection of health measures before and after treatment. The psychometric properties of three measures of physical function (MSIS-29 physical, SF-36 physical functioning, FAMS mobility) and three measures of psychological function (MSIS-29 psychological, SF-36 mental health, FAMS emotional well-being) were compared by examining data quality, scaling assumptions, acceptability, reliability, validity and responsiveness. Physical (0.63-0.71) and psychological (0.70-0.75) scales were substantially correlated indicating they measure related constructs. The MSIS-29 physical and psychological scales satisfied all criteria for internal consistency reliability (physical = 0.91; psychological = 0.89) and validity. The SF-36 physical scale had a notable floor effect (20%). The FAMS mobility scale had lower reliability (alpha = 0.78) compared to other measures. The MSIS-29 physical (effect size = 0.91) and psychological (effect size = 0.62) scales were the most responsive. In these three samples, the MSIS-29 had better measurement properties for combined physical and psychological health than the SF-36 and the FAMS.

A randomized controlled study of modified cobratoxin in adrenomyeloneuropathy.

Adrenomyeloneuropathy is a peroxisomal disorder that causes demyelination, with no proven therapy. Oral modified cobratoxin was assessed in a double-blind, randomized, crossover study of eight patients. Treatment was well tolerated. There were no significant improvements with therapy. The authors do not confirm previous anecdotal reports of dramatic improvement with modified cobratoxin.

Using the SF-36 measure to compare the health impact of multiple sclerosis and Parkinson's disease with normal population health profiles.

OBJECTIVE: To examine the relative impact of two chronic neurological disorders, multiple sclerosis and Parkinson's disease, by comparing patients' scores on the medical outcomes study 36-item short form health survey (SF-36) with the health profile of the United Kingdom population norms. METHODS: 638 people representing the full spectrum of multiple sclerosis and 227 patients with Parkinson's disease were studied. Health status was measured by the SF-36. Scores for the eight health domains were compared after controlling for age, sex, disease duration, mobility, social class, ethnicity, education, marital status, and employment status. RESULTS: People with multiple sclerosis and those with Parkinson's disease had significantly worse health than the general population on all eight domains measured by the SF-36. The relative impact of multiple sclerosis and Parkinson's disease were similar, but multiple sclerosis resulted in poorer scores on physical functioning and better scores in mental health. People with mild multiple sclerosis who walked without an aid also had significantly worse scores in all dimensions than the general UK population. CONCLUSIONS: The results highlight the need for further research into aspects of health measured by the SF-36. Nevertheless, generic measures that are applicable across multiple diseases may fail to address clinically important aspects of the impact of specific disorders.

Measuring the impact of MS on walking ability: the 12-Item MS Walking Scale (MSWS-12).

OBJECTIVE: To develop a patient-based measure of walking ability in MS. METHODS: Twelve items describing the impact of MS on walking (12-Item MS Walking Scale [MSWS-12]) were generated from 30 patient interviews, expert opinion, and literature review. Preliminary psychometric evaluation (data quality, scaling assumptions, acceptability, reliability, validity) was undertaken in the data generated by 602 people from the MS Society membership database. Further psychometric evaluation (including comprehensive validity assessment, responsiveness, and relative efficiency) was conducted in two hospital-based samples: people with primary progressive MS (PPMS; n = 78) and people with relapses admitted for IV steroid treatment (n = 54). RESULTS: In all samples, missing data were low (< or =3.8%), item test-retest reproducibility was high (> or =0.78), scaling assumptions were satisfied, and reliability was high (> or =0.94). Correlations between the MSWS-12 and other scales were consistent with a priori hypotheses. The MSWS-12 (relative efficiency = 1.0) was more responsive than the Functional Assessment of Multiple Sclerosis mobility scale (0.72), the 36-Item Short Form Health Survey physical functioning scale (0.33), the Expanded Disability Status Scale (0.03), the 25-ft Timed Walk Test (0.44), and Guy's Neurologic Disability Scale lower limb disability item (0.10). CONCLUSIONS: The MSWS-12 satisfies standard criteria as a reliable and valid patient-based measure of the impact of MS on walking. In these samples, the MSWS-12 was more responsive than other walking-based scales.

Multiple Sclerosis Impact Scale (MSIS-29): reliability and validity in hospital based samples.

BACKGROUND AND AIM: The psychometric properties of rating scales are sample dependent and need evaluations in different samples. The Multiple Sclerosis Impact Scale (MSIS-29), a new patient based rating scale for multiple sclerosis (MS) was predominantly developed from a community based sample derived from the MS Society. A number of important patient characteristics of this sample remain unknown. The aim of the study was to evaluate five psychometric properties of the MSIS-29 in three hospital based samples: people admitted for rehabilitation, people admitted for intravenous corticosteroid treatment for MS relapses, and people with primary progressive MS. METHODS: People with MS were recruited from the three clinical settings. They completed several health measures. MSIS-29 data were evaluated for data quality, scaling assumptions, acceptability, reliability and validity, and compared with those from a previously reported community based study. RESULTS: A total of 233 people (rehabilitation p=53; corticosteroids p=76; primary progressive p=104) completed questionnaires. In all samples, missing data were low (or=0.91). Correlations between the MSIS-29 and other scales were consistent with a priori hypotheses. Findings were consistent with those from the community samples. CONCLUSIONS: The psychometric properties of the MSIS-29 are consistent across three hospital based samples, and similar to those in the community samples. These findings further support its use as an outcome measure in different clinical settings.

Evidence-based measurement: which disability scale for neurologic rehabilitation?

OBJECTIVE: To compare the 10-item Barthel Index (BI), 18-item Functional Independence Measure (FIM), and 30-item Functional Independence Measure + Functional Assessment Measure (FIM+FAM) as measures of disability outcomes for neurologic rehabilitation. METHODS: A total of 149 inpatients from two rehabilitation units in South England specializing in neurologic disorders were studied. Traditional psychometric methods were used to evaluate and compare acceptability (score distributions), reliability (internal consistency, intrarater reproducibility), validity (concurrent, convergent and discriminant construct), and responsiveness (standardized response mean). RESULTS: All three rating scales satisfied recommended criteria for reliable and valid measurement of disability, and are acceptable and responsive in this study sample. The FIM and FIM+FAM total scales are psychometrically similar measures of global disability. The BI, FIM, and FIM+FAM motor scales are psychometrically similar measures of physical disability. The FIM and FIM+FAM cognitive scales are psychometrically similar measures of physical disability. CONCLUSIONS: In the sample studied, the BI, FIM, FIM+FAM have similar measurement properties, when examined using traditional psychometric analyses. Although instruments with more items and item response categories generate more qualitative information about an outcome, they may not improve its measurement. Results highlight the importance of using recognized techniques of scale construction to develop health outcome measures.