FUNCTIONAL LIMITATION OF the upper extremitys

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1 1086 ORIGINAL ARTICLE Validity, Responsiveness, and Clinically Important Difference of the ABILHAND Questionnaire in Patients With Stroke Tien-ni Wang, PhD, OT,* Keh-chung Lin, ScD, OTR,* Ching-yi Wu, ScD, OTR, Chia-ying Chung, MD, Yu-cheng Pei, MD, PhD, Yu-kuei Teng, MS ABSTRACT. Wang T, Lin K, Wu C, Chung C, Pei Y, Teng Y. Validity, responsiveness, and clinically important difference of the ABILHAND questionnaire in patients with stroke. Arch Phys Med Rehabil 2011;92: Objective: To investigate the criterion-related validity, responsiveness, and clinically important differences of the ABIL- HAND questionnaire in patients with stroke. Design: Validation and clinimetric study. Setting: Three medical centers. Participants: Patients with stroke (N 51). Interventions: A total of 51 patients with stroke received 1 of 3 upper extremity rehabilitation programs for 4 weeks. Main Outcome Measures: The ABILHAND and the criterion measures, including the Stroke Impact Scale (SIS), FIM, Nottingham Extended Activities of Daily Living (NEADL), and accelerometers, were administered at pretreatment and posttreatment. The score of the ABILHAND, given in logits, was based on the conversion of the ordinal score into a linear measure of ability. Results: Correlation coefficients (Pearson r) were moderate to large between the ABILHAND and SIS physical domains (.54.66), fair to moderate between the ABILHAND and FIMmotor and NEADL (.28.48), and moderate between the ABILHAND and accelerometer data (.45.54). The responsiveness of the ABILHAND was large (standardized response mean 1.27). The minimal clinically important difference range for the ABILHAND was.26 to.35, and 51.0% of the patients showed a positive change that exceeded the lower bound of a clinically important difference after intervention. Conclusions: The results support that the ABILHAND is an appropriate outcome measure for assessing upper extremity performance in daily activities in patients with stroke and is sensitive to detect change after rehabilitative interventions. The change score of a patient with stroke on the ABILHAND From the Department of Occupational Therapy and Graduate Institute of Behavioral Sciences, College of Medicine, Chang Gung University, Taoyuan (Wang, Wu); School of Occupational Therapy, College of Medicine, National Taiwan University, and Division of Occupational Therapy, Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei (Lin); Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Tao-yuan (Chung, Pei); Graduate Institute of Clinical Medical Science, College of Medicine, China Medical University, Taichung (Teng), Taiwan. Supported in part by the National Health Research Institutes (NHRI-EX PI, NHRI-EX PI), the National Science Council (NSC B MY3, NSC B MY3), and the China Medical University research fund (99F ) in Taiwan. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. Correspondence to Ching-yi Wu, ScD, OTR, Department of Occupational Therapy and Graduate Institute of Behavioral Sciences, Chang Gung University, 259 Wen-hwa 1st Rd, Kwei-shan, Tao-yuan, Taiwan, cywu@mail.cgu.edu.tw. Reprints are not available from the authors. *Wang and Lin contributed equally to this manuscript. Chung and Pei contributed equally to this manuscript /11/ $36.00/0 doi: /j.apmr should reach.26 to.35 logits points to be regarded as a clinically important change. Key Words: Psychometrics; Rehabilitation; Stroke; Upper extremity by the American Congress of Rehabilitation Medicine FUNCTIONAL LIMITATION OF the upper extremitys (UEs) is one of the most common disabling deficits after stroke. 1 Approximately 30% to 66% of stroke survivors report persistent movement impairment of their UE and are unable to use their affected arm in the activities of daily living (ADLs). 2,3 Studies show that UE impairment is associated with difficulties in overall physical function, daily activity participation, and thus reduced quality of life in patients with stroke. 4-7 Describing the recovery course of UE impairment and improving UE control to promote functional recovery in daily performance are critical to stroke rehabilitation. Because many natural daily activities require bilateral movements, 8 unlike the existing manual ability tests that are built on artificial or unimanual tests, 9,10 the ABILHAND 11 is a scale measuring bimanual ability that is often used to determine the level of UE dysfunction during the recovery course of patients with stroke. Constraint-induced therapy, 12,13 bilateral arm training, virtual reality, 17 and robotic training 18,19 are among the various contemporary evidence-based rehabilitation strategies that have been reported to improve UE motor deficits after stroke. Clinicians and researchers need to identify appropriate measures that have sound clinimetric properties to determine the effects of UE training. 20 An increasing number of studies have adopted the ABILHAND 11 as the outcome measure to determine UE rehabilitation effectiveness. 17,18,21,22 Because patients with stroke often use their unaffected limb when performing unimanual ADL, 23 the ABILHAND, which evaluates the bimanual skills in daily activities, directly captures the real UE performance that reflects the treatment effects in the patient s daily routines. 10 The reliability and criterion-related validity of the ABILHAND in patients with stroke have been reported. 10,24 The psychometric study by Penta et al 10 reported that the Rasch reliability of the ABILHAND was.90, and the item-difficulty hierarchy was stable across demographic and clinical subgroups in a stroke population. Criterion-related validity in- ADL CID NEADL SIS SRM UE VAS List of Abbreviations activity of daily living clinically important difference Nottingham Extended Activities of Daily Living Stroke Impact Scale standardized response mean upper extremity visual analog scale

2 CLINIMETRIC PROPERTIES OF THE ABILHAND, Wang 1087 cludes concurrent validity and predictive validity, which considers the degree of consistency of an instrument with the criterion measures and the ability of an instrument to predict subsequent events. 25 Most of the validity studies on the ABILHAND demonstrated that the ABILHAND measured the concept of motor ability in a standardized or natural environment by significant correlations between the ABILHAND and grip strength, motricity, dexterity, or actual UE performance as measured by the accelerometers. 10,24 Whether the ABILHAND assesses the functional ability at the activity/ participation level remained unknown. Furthermore, no predictive validity of the ABILHAND was investigated. Because the ABILHAND is increasingly used as an outcome measure in clinical studies, its clinimetric properties, including responsiveness and clinically important difference (CID), must be studied to determine whether it is sufficient to detect changes as well as whether these changes are clinically relevant. Responsiveness is defined as the ability of an instrument to detect changes as a result of rehabilitation. 26,27 It is essential for assessing the effectiveness of treatment as well as for measuring longitudinal change over a defined period of treatment. Within this change, the CID can provide additional information that constitutes a score change that is related to a meaningful change in the specific assessment. 28 The CID is defined as the smallest change in an outcome measure perceived as beneficial to patients. 29,30 The CID is important for consideration in interpretations of patient-reported outcomes because a statistically meaningful change is not synonymous with a clinically important change. Anchorbased and distribution-based approaches have both been proposed to determine the CID. 30,31 The distribution-based method calculates CID values from the data generated from the instrument without reference to an external standard. 32 The anchor-based method estimates CID values by comparing change scores with an anchor, often a patient s or a clinician s global rating of change. 33 Because there is no universally accepted standard for the determination of CID values and no single true CID value for an instrument, combinations of the anchor-based and distribution-based approaches to triangulate on a small range of values for the CID have been suggested. 31,34 For clinicians and researchers studying and treating UE impairment, a UE measure with sound psychometric and clinimetric properties is indispensable to facilitate interpretation and comparison of the results of controlled trials. Use of appropriate measures for outcome evaluations would enhance the methodologic quality of controlled trials in stroke rehabilitation research. 20 The purpose of this study was therefore to examine the concurrent and predictive validity of the ABIL- HAND and its clinimetric properties, including the responsiveness and CID, in patients with stroke. METHODS Participants We recruited 51 participants from 3 medical centers who were enrolled in ongoing research projects investigating the efficacy of robot-assisted training. The inclusion criteria for the participants were as follows: (1) must be onset of a first-ever stroke, (2) must be able to reach Brunnstrom stage II or above 35 for the proximal and distal UE, (3) must have no excessive spasticity in the shoulder and elbow joints of the affected UE (Modified Ashworth Scale 36 2), (4) must have no cognitive impairment (Mini-Mental State Examination score 37 24), (5) no upper-limb fracture within 3 months, (6) no participation in any experimental rehabilitation or drug studies during the study period, and (7) willing to provide written informed consent. Institutional review board approval was obtained from the study sites, and written informed consent was obtained from each patient before inclusion. Intervention and Procedure Eligible participants received 1 of the 3 UE rehabilitation programs: bilateral robot-assisted training, unilateral robotassisted training, or conventional rehabilitation. 38 All participants received a 1.5-hour therapy session 5 times a week for 4 weeks. The interventions were provided at the participating hospitals under the supervision of 3 certificated occupational therapists. The raters were blind to the participant group and trained to administer the outcome measures properly. Rater competence was assessed by a senior certified occupational therapist. The same rater administered to each participant all the measurements of this study at baseline and after the 4-week intervention. Measures The measurement tools used in this study were the ABILHAND and criterion measures, including the Stroke Impact Scale (SIS), FIM, Nottingham Extended Activities of Daily Living (NEADL), and Stroke Upper-Limb Activity Monitor. The SIS represents self-perception about the quality of life during activity participation. The FIM and NEADL represent performance of basic and instrumental ADL. Kelly- Hayes et al 39 suggested assessment of both basic and extended ADLs may comprehensively reflect a person s function at activity/participation levels. The Stroke Upper-Limb Activity Monitor measures the UE activity performance in the real world. ABILHAND. The ABILHAND 11 is a Rasch-based assessment that measures patients perceived difficulty in performing ADLs that require the use of the bilateral upper limbs. It contains 23 items measuring manual ability and is rated on a 3-point response scale. The score, given in logits, is the conversion of the ordinal score into a linear measure of ability located on a unidimensional scale. Stroke impact scale. The SIS, a self-report questionnaire and a comprehensive measure of health-related quality of life in patients with stroke, has established reliability and validity. 40,41 It uses a 5-point Likert scale to rate 59 items that assess the effect of stroke in 8 functional domains: strength, memory, emotion, communication, ADLs/instrumental ADLs, mobility, hand function, and participation. The SIS provides domain scores and a summary score, with higher scores indicating better function. Only the subscales related to the physical domains, including strength, self-care, and UE function, were summed and used in this study to investigate the validity. FIM. The FIM, 42 with sound psychometric properties, 43,44 consists of 18 items grouped into 6 subscales measuring selfcare, sphincter control, transfer, locomotion, communication, and social cognition ability. Each item is rated from 1 to 7 based on the required level of assistance to perform the basic ADL. Higher scores demonstrate greater independent participation in ADLs. The 9 items of self-care and transfer subscales that may involve UE function were summed to create a FIM UE score with a range of 9 to 63. Nottingham extended activities of daily living. The NEADL scale 45 incorporates 22 ADL activities scored on the basis of the requirement for help in performing the activity. It gives scores on 4 subscales (mobility, domestic, leisure, kitchen) and a total score that has been shown to have good psychometric properties in patients with stroke. 46 The scoring

3 1088 CLINIMETRIC PROPERTIES OF THE ABILHAND, Wang range is from 0 to 22, with higher scores representing better function in performing ADLs. The mobility subscale was excluded from the validation study because it might be less relevant to UE function. Stroke Upper-Limb activity monitor. The Stroke Upper- Limb Activity Monitor measures actual arm movement by using accelerometers. Two accelerometers, each about the size of a large wristwatch, were placed on both wrists. Accelerometers were worn on both arms because a single unit worn on the affected side might act as a cue to use that extremity and thereby confound the measurement of the effects of rehabilitation on arm function. In addition, a previous study suggested that the ratio of affected to unaffected arm recordings to changes in overall levels of physical activity is desirable because this ratio is proposed as outcome measure for interventions designed to improve real-world use of the affected arm. 47 Table 1: Demographic and Clinical Characteristics of the Participants (N 51) Characteristic Value Sex (n) Male 34 Female 17 Age (y), mean SD Side of stroke (n) Right 25 Left 26 Months after stroke, mean SD Brunnstrom stage, median (range) Proximal upper extremity 4 (3 5) Distal upper extremity 3 (2 5) Modified Ashworth Scale, mean SD ABILHAND at pretreatment, logits score, mean SD Table 2: Concurrent and Predictive Validity of the ABILHAND Criterion Measures Baseline Concurrent Posttreatment Predictive SIS physical function FIM-motor NEADL.28*.38.29* Accelerometers *P.05; P.01. Data Analysis Estimation of criterion-related validity. Pearson correlation coefficients (r) were used to examine concurrent validity by correlating the ABILHAND with 4 related assessments (SIS, FIM, NEADL, accelerometers) at baseline and at follow-up and to assess predictive validity between the ABILHAND at baseline and the criterion measures at posttreatment evaluation. Correlations between 0 and 0.25 were considered low, those between 0.25 and 0.5 were considered fair, those between 0.5 and 0.75 were considered moderate to good, and those greater than 0.75 were considered good to excellent. 48 Estimation of responsiveness. The responsiveness of the ABILHAND was examined according to changes from pretreatment to posttreatment by the following 2 indices. The paired t test was performed to determine whether statistically significant differences in mean change score had occurred. The standardized response mean (SRM) was estimated as the ratio of the mean change score to the SD of the mean change score. 26 Patients who did not benefit from the treatment were excluded from the estimation of responsiveness. The Cohen criteria for effect size d was used to classify the values of SRM as nonresponsive ( 0.2), small ( ), medium ( ), and large ( 0.8). 49 Estimation of CID. Distribution-based and anchor-based methods were adopted to triangulate the ranges of minimal CIDs. The anchor-based CID estimate was calculated as the mean change score on the ABILHAND, corresponding to patients who perceived overall increased recovery of 10% to 15% on the SIS. We chose the SIS as the anchor during the calculation of CID estimates because the overall recovery ratings on the SIS directly reflect the participants viewpoints on their health-related recovery. 50,51 Although there is no defined range of the change score for the determination of the CID group, several previous studies have found the smallest change score of 8% on the Zung Depression Scale total score, 10% on the 100-mm visual analog scale (VAS) of quality of sleep, 52 11% on the 100-point Pediatric Evaluation of Disability Inventory, 53 and 15% on the 100-mm VAS of back pain. 54 Therefore, in the current study, patients were classified into the CID group if a 10% to 15% change was documented on their perceived overall recovery from pretreatment to posttreatment and they were considered to have experienced a clinically important change. In addition, the distribution-based CID estimate was determined using the Cohen effect size 49 benchmark, which is widely accepted. 32,55 An effect size of 0.2 was advocated as a reasonable method to estimate the minimal CID. 30,54 Thus, an effect size of 0.2 (ie, 0.2 SD of baseline score), indicating a small but important change, was used to estimate the minimal threshold of CID in this study. To assess the extent of patients changes after interventions detected by the ABILHAND, the proportions of patients with change scores exceeding the values of the anchor-based and distribution-based CID estimates were examined. The greater the proportion of patients who exceeded the values, the more sensitive the measure was. RESULTS The demographic and clinical characteristics of the participants are summarized in table 1. Their mean age was 55 years, and 67% were men. The interrelationships of data obtained with the ABILHAND, SIS, FIM, NEADL, and accelerometers were all statistically significant (P.05; table 2). Correlations between the ABILHAND and SIS physical domains were relatively high (Pearson r.54.66), correlations between the ABILHAND and FIMmotor and NEADL were fair to moderate (Pearson r.28.48), and the relationship between the ABILHAND and actual arm use as measured by the accelerometers was moderate (Pearson r.45.54). The responsiveness and CID indices of the ABILHAND are listed in table 3. The pretreatment to posttreatment change assessed by the ABILHAND was significant (t 1.96; P.05), and the responsiveness of the ABILHAND was large from pretreatment to posttreatment (SRM 1.27). As calculated Scale Table 3: Responsiveness and CID of the ABILHAND Responsiveness CID, Score (%) Paired t test SRM Anchor-Based Distribution-Based ABILHAND 1.96* (47.1).26 (51.0) *P.05. Proportion of participants who met the criteria of the CID.

4 CLINIMETRIC PROPERTIES OF THE ABILHAND, Wang 1089 from the 12 patients whose SIS change score reached 10% to 15%, the anchor-based CID estimate was.35 logits for the ABILHAND. In addition, the distribution-based CID estimates (ie, 0.2 SD) for the ABILHAND equated to a change of.26. Furthermore, 47.1% and 51.0% of patients had a positive change that exceeded the anchor-based and distribution-based CID of the ABILHAND, respectively. DISCUSSION To our knowledge, this study is the first to examine the concurrent and predictive validity between the ABILHAND and assessments measuring functional ability at the activity/ participation level. This is also the first one to investigate the responsiveness and CID of the ABILHAND in a stroke population. The results of this study extend the validation study by Penta 10 that examined the concurrent validity of the ABIL- HAND by comparing it with motor performance tests such as grip strength and dexterity. This study adds knowledge to confirm the ABILHAND is also significantly correlated to UE function and participation in daily activities in patients with stroke as measured by the SIS, FIM, and NEADL. These findings suggest that the ABILHAND is valid not only to measure motor abilities of patients with stroke but also to assess their UE function in daily life. In addition, although the functional questionnaires used in this study all measured the UE function in performing ADLs, we note that the correlation of the ABILHAND and the SIS (moderate to good, r.54.66) is stronger than that of the ABILAHND and the FIM/NEADL (fair to moderate, r.28.48). One possible reason for the difference might be the natural characteristics of these assessments. The ABILHAND and SIS both assess the UE function in performing daily activities by rating the difficulty, whereas the FIM and NEADL assess that by scoring the patient s independence (whether the patients need assistant to participate). Another possibility is that the physical function of the SIS required patients responses in both aspects of basic and instrumental ADLs as well as motor abilities such as hand function and strength, whereas the FIM and NEADL tapped either basic or instrumental ADLs, respectively, suggesting that the ABILHAND might be better related to both aspects of ADLs together with motor abilities than 1 aspect of ADLs alone. The correlation between the ABILHAND and actual arm use as measured by the accelerometers was moderate, consistent with previous studies. 24,56 The self-perceived activity performance (the ABILHAND) provided subjective information about the manner in which someone experiences the difficulties caused by the disability, 11 whereas the actual activity performance measured by the accelerometers provided objective information about the manner in which the disability affects one s functioning in daily life. The patient-perceived UE performance is significantly and moderately related to actual daily activity performance, suggesting that the patient s perceived difficulty in bimanual tasks might reflect the patient s actual performance to a moderate extent. Understanding the relationship between self-perceived and actual activity performance is particularly important in rehabilitation trials designed to improve impairments in manual skills and real-world performance. 24,57 The correlation of the ABILHAND and actual arm use (moderate, r.46.54) is close to that of the ABILHAND and the SIS (moderate to good, r.54.66) and generally stronger than that of the ABILAHND and the FIM/NEADL (fair to moderate, r.28.48). Patients were asked to wear the accelerometer all day, and it recorded the amount of all patient activities all day. The recording might involve all aspects of ADL, possibly including basic and instrumental ADLs, leading to a stronger relationship of the ABILHAND and the accelerometer than that of the ABILHAND and the FIM/NEADL. In general, the correlations among the tests fluctuate only slightly at pretreatment and posttreatment, suggesting that the relationships among the tests are relatively stable over 4-week interventions, which reflects constant relationships among the tests and establishes sound predictive validity of the ABILHAND. Together with the results of predictive validity, the findings of this study lent support for the criterion-related validity of the ABILHAND as an outcome measure for assessing UE performance at the activity participation level in stroke survivors. Assessment of sensitivity to change is important if a scale is to be used in treatment evaluation studies. The large magnitude of SRM (1.27) for the ABILHAND in this study provides evidence that the ABILHAND is a responsive assessment that is sensitive to change over time. The study result is in line with findings of previous studies that reported the large responsiveness for other UE functional assessments (eg, the SRMs of the Fugl-Meyer Assessment, Action Research Arm Test, and Motor Activities Log are 1.42,.95, and , respectively). 43,56 Nevertheless, the ABILHAND is unique in that it is a self-report questionnaire aiming to measure patients bimanual skills in ADL. Because many natural daily activities require bilateral movements 8 and a patient-reported measure represents patients real perception of rehabilitation effectiveness, 58 the ABILHAND provides comparable clinimetric properties and is suggested to be administered as one of the UE outcome measures in stroke rehabilitation clinics as well as in effectiveness studies. Because there is no criterion standard for estimating the scores of the minimal CID, triangulation of the results to identify the CID is suggested. 30 We adopted the combination of the anchor-based and distribution-based approaches. In this study, the CID estimate derived from an anchor of SIS, which reflects the participant s viewpoint on health-related functional recovery, was.35, and the distribution-based CID was.26 for the ABILHAND. Combining the 2 approaches to establish the CID, we recommend that the changes must be in the range of a.26 to.35 logits score on the ABILHAND to meet the requirements for minimal CID. Thus, patients with stroke who achieve a change score of.26 on the ABILHAND are likely to have had a clinically important change in their bimanual UE function in ADLs. Taking this cohort sample of stroke rehabilitation as an example, the mean change score on the ABIL- HAND was.27, which exceeded the lower bound of the minimal CID range. The results indicate that the improvement achieved after rehabilitative therapies in this cohort could be interpreted as both statistically significant and clinically important. Furthermore, we reported the proportion of patients who met the CID requirements to provide more insightful and intuitive clinical interpretations than considering the overall mean change scores. 59,60 On the basis of our sample, 51% of patients achieved a change score that exceeded the minimal CID of the ABILHAND, indicating that more than half of the patients with stroke perceived improvement of UE performance in daily activities. Study Limitations A few limitations of this study warrant consideration. First, previous studies 30,59 pointed out that the CID score might be different depending on the patient s baseline level of disability. A larger sample of patients with stroke and differing levels of motor impairment is necessary to verify the current study results. Second, because our responsiveness and CID estimates of the ABILHAND were derived from patients whose

5 1090 CLINIMETRIC PROPERTIES OF THE ABILHAND, Wang ABILHAND scores improved from pretreatment to posttreatment, the results are applicable only for patients who improved. Third, because we only included first-ever patients with ischemic stroke without major cognitive disabilities and who did not have excessive spasticity in the shoulder and elbow joints, the results of this study may not be suitable for other groups of patients with stroke. CONCLUSIONS The ABILHAND demonstrated good criterion-related validity and responsiveness properties in patients with stroke. The ABILHAND is well related to and predicts UE function and participation in daily activities in patients with stroke. The results of the responsiveness and CID of the ABILHAND add information about the clinimetric properties that facilitate the interpretation of the change scores in stroke rehabilitation. 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