Barthel Index and modified Rankin Scale: Psychometric properties during medication phases in idiopathic Parkinson disease

Journal Pre-proof Barthel Index and modified Rankin Scale: psychometric properties during medication phases in idiopathic Parkinson disease Ghorban Taghizadeh Pablo Martinez-Martin Mahsa Meimandi Sayed Amir Hasan Habibi Shamsi Jamali Ariyan Dehmiyani Siavash Rostami Alieh Mahmuodi Maryam Mehdizadeh Seyed-Mohammad Fereshtehnejad

PII:

S1877-0657(19)30185-X

DOI:

https://doi.org/doi:10.1016/j.rehab.2019.08.006

Reference:

REHAB 1337

To appear in:

Annals of Physical and Rehabilitation Medicine

Received Date:

18 March 2019

Accepted Date:

23 August 2019

Please cite this article as: Taghizadeh G, Martinez-Martin P, Meimandi M, Habibi SAH, Jamali S, Dehmiyani A, Rostami S, Mahmuodi A, Mehdizadeh M, Fereshtehnejad S-Mohammad, Barthel Index and modified Rankin Scale: psychometric properties during medication phases in idiopathic Parkinson disease, Annals of Physical and Rehabilitation Medicine (2019), doi: https://doi.org/10.1016/j.rehab.2019.08.006

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Barthel Index and modified Rankin Scale: psychometric properties during medication phases in idiopathic Parkinson disease Ghorban Taghizadeh1, Pablo Martinez-Martin2, Mahsa Meimandi1, Sayed Amir Hasan Habibi3, Shamsi Jamali1, Ariyan Dehmiyani1, Siavash Rostami1, Alieh Mahmuodi4, Maryam Mehdizadeh5,6,7*, Seyed-Mohammad Fereshtehnejad 8,9,10 Rehabilitation Research Center, Department of Occupational Therapy, School of Rehabilitation

Sciences, Iran University of Medical Science, Tehran, Iran

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National Center of Epidemiology and CIBERNED, Carlos III Institute of Health, Madrid, Spain

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Department of Neurology, Rasoul Akram Hospital, Iran University of Medical Science, Tehran,

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Iran

Department of Aging, University of Social Welfare Rehabilitation Sciences, Tehran, Iran

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Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran

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Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of

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Medical Sciences, Tehran, Iran 7

Student Research Committee, Iran University of Medical Sciences, Tehran, Iran

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Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society (NVS),

Karolinska Institutet, Stockholm, Sweden 9

Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada

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Division of Neurology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada

*Corresponding Author: 1 Page 1 of 13

Maryam Mehdizadeh, Department of Neurosciences Faculty of Advanced Technologies in Medicine Iran University of Medical Sciences

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Shahid Hemmat Highway

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Tehran, 1449614535, Iran

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Tel: +98-9129454770; [email protected]

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phases in idiopathic Parkinson disease

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Barthel Index and modified Rankin Scale: psychometric properties during medication

Abstract

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Background. Independence in activities of daily living (ADL) is one of the most important aspects in planning treatment for people with Parkinson disease (PD). The Barthel Index (BI) and modified

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Rankin Scale (mRS) are commonly used in neurological diseases.

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Objective. This study was conducted to confirm the validity and reliability of the BI and mRS in PD during ON and OFF medication phases. Methods. We included 260 individuals with a diagnosis of idiopathic PD. The disability in ADL was measured by the BI, mRS, Parkinson's Disease Questionnaire-39 (PDQ-39), Unified Parkinson Disease Rating Scale-Activities of Daily Living (UPDRS-ADL), and Schwab and England ADL scale (SE). Test–retest, inter-rater reliability, and internal consistency were assessed by the intraclass correlation (ICC) and Cronbach α coefficients. Dimensionality was evaluated by factor

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analysis. Convergent validity was assessed by the SE, Berg Balance Scale (BBS), PDQ-39 and UPDRS-ADL. Results. For the 260 participants (187 [71.9%] males; mean [SD] age 60.3 [12.3] years), both the BI and mRS achieved an acceptable level of test–retest and inter-rater reliability (ICC = 0.77 to 0.91) in ON and OFF medication phases. The Cronbach α for BI was 0.85 and 0.88, respectively.

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We found 1 and 2 factors for BI in ON and OFF phases, respectively. Investigation of convergent

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validity showed moderate to high correlation for the BI with the UPDRS-ADL, SE, PDQ-39 (ADL), BBS and mRS scores in ON and OFF phases (ρ=0.51-0.74) and mRS with SE, UPDRS-

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ADL, PDQ-39 (ADL) and BBS scores (ρ=0.48-0.82).

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Conclusion. The BI and mRS showed acceptable validity and reliability to measure the degree of

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disability in patients with PD in daily activities in both ON and OFF medication phases. Keywords. idiopathic Parkinson disease, disability measures, reliability, ON and OFF medication,

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validity

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Introduction

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Loss of independence in basic activities of daily living (ADL) such as eating, personal hygiene, and using medication results from reduced performance and disease progression in Parkinson disease (PD) (1). Evaluating disability in ADL is considered the most important aspect of assessment for a precise judgment on the effect of pharmacological and non-pharmacological treatments in idiopathic PD (2-4). Numerous assessment tools are available for assessing disability in PD. The Schwab and England ADL scale (SE) and the Unified Parkinson Disease Rating Scale-Activity of Daily Living (UPDRS-ADL) are widely used for assessing independency in ADL for people with PD (5-7). 3 Page 3 of 13

Extensive application of available disability scales in PD will expand our knowledge of PD impairments and daily function. The Barthel Index (BI), with 10 items for mobility and ADL areas, is considered the most convenient measure of competency in basic ADL in neurological and musculoskeletal disorders. Only the self-reporting version of the BI has been validated in PD (8-10). Another commonly used

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scale in neurological diseases is the modified Rankin Scale (mRS), a brief and easy-to-administer

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scale measuring 6 levels of global ability to perform activities. It describes the degree of disability in diverse states, including PD. Although BI and mRS are frequent scales in neurological settings,

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the original version of the BI (clinicians’ ratings by interview) and the psychometric properties of

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the mRS have not been determined for PD (11).

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In people with PD, the presence of fluctuations in motor performance between an ON medication phase (i.e., when disease symptoms are controlled with medication) and an OFF phase (i.e., when

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disease symptoms reappear) should be considered in assessing disability level (12-14). This way, information regarding the variability in performance throughout the medication cycle could be

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obtained to estimate and monitor its impact on the patient’s functional ability (15, 16).

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According to suggestions from past studies, to determine a useful scale in PD, the degree of disability during ON and OFF medication phases should be assessed (11). However, no scales assessing disability have been validated for this aim (11). Therefore, the purpose of our study was to assess the psychometric properties of the BI and mRS during medication phases in idiopathic PD. Methods

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In total, 260 individuals with a diagnosis of idiopathic PD participated in this non-randomized, observational study. Consecutive patients were screened at the movement disorders outpatient clinic of the Iran University of Medical Sciences based on the following inclusion criteria: diagnosis of idiopathic PD by a neurologist (according to UK Brain Banks Network criteria), lack of cognitive problems (Mini Mental Status Examination score > 21) (17), native in Persian

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language and ability to read and understand items in ON and OFF medication phases (15).

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Two experienced occupational therapists assessed the level of independence in daily activities via interview by administering the SE, UPDRS-ADL, PDQ-39 (ADL dimension), BI and mRS in a

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random order in both medication phases: ON (1 hr after levodopa administration) and OFF (12 hr

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after the last evening dose of levodopa) (15). Assessments were performed in a quiet and well-

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lighted room for both test and retest conditions. The time between the test and retest was 7 to 14 days.

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The current study was approved by the Student Research Committee of Iran University of Medical Sciences (ethical code: IR.IUMS.rec.1393.24849). All participants gave signed informed consent

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Assessments

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to be in the study. A code number was placed on each participant’s name to protect confidentiality.

The SE has 11 levels of general ability to perform chores. This scale is scored from 0 to 100%; a lower score indicates less level of independency (7). The UPDRS-ADL is a PD-specific measure of behavior, cognition, ADL and motor performance in PD. The ADL section contains 13 items rated on a 4-point Likert scale to be scored in ON and OFF phases in patients with fluctuations between ON and OFF drug phases. The total score for this

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section ranges from 0 to 52; a lower score represents less disability to perform ADL in PD. This section has strong validity and reliability (18, 19). The BI is a widely used measure of disability in ADL. The BI includes 10 items in 2 major areas of self-care activities (including feeding, bathing, grooming, bowl and bladder control, dressing and toileting) and mobility (including transfer, mobility and using stairs). Scores range from 0

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(disabled) to 100 (very independent). The Persian version of BI has shown appropriate validity and

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reliability in stroke survivors (20).

The mRS is a brief and easy to use “global functional health index with a strong emphasis on

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physical disability.” This scale measures 6 levels of general ability and is used in neurological

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conditions other than PD. Scores range from 0 to 6, the latter indicating severe disability and

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dependence in ADL. The Persian version has been validated in stroke (20). The PDQ-39 is a specific questionnaire for measuring quality of life in people with PD. This questionnaire has 39 items in 8 dimensions of health including ADL, mobility, emotional well-

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being, stigma, social support, cognition, communication and bodily discomfort rated on a 5-point

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(0-4) Likert scale. In this study, only the ADL section (items 11-16) was used. Scores range from

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0 to 24 in the ADL section (transformed to a percentage of the maximum possible score of the dimension) and perceived ability to perform ADL. Psychometric properties of the Persian version of PDQ-39 have been tested in idiopathic PD in Iran (21). The BBS is a measure of static and dynamic balance in standing. This scale contains 14 items rated on a 4-point Likert scale. A score of 56 shows the best balance. The Persian BBS has shown excellent reliability in PD (22). Statistical analysis

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Demographic characteristics and total scores of the BI and mRS were calculated based on descriptive statistics (mean [SD], percentages). The Shapiro-Francia test was used to test for normality of the distribution of scores. For measuring acceptability, we determined ceiling and floor effects. We recorded the number and proportion of participants obtaining the minimum or maximum possible score for the BI and mRS. Floor or ceiling effects were considered acceptable

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if less than 15% of the responders achieved the minimum or maximum possible score, respectively

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(23). The acceptable skewness range was from -1 to +1 (24). For investigating the BI dimensionality, the factor structure was examined by exploratory factor analysis (EFA), principal

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component analysis and varimax rotation (eigenvalues > 1) (25). Internal consistency of the BI was

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calculated with the Cronbach α coefficient, acceptable at ≥0.9 for clinical application (26). To determine the association between each item and total score and items with each other, we

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calculated corrected item–total and inter-item correlation coefficients. Coefficients ≥0.20 were considered acceptable (27). The test–retest and inter-rater reliability of the total score of the BI and

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mRS was calculated by using intra-class correlation (ICC) coefficients (two-way and one-way,

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respectively, single measure, and 95% confidence interval [CI]) (27, 28). ICC values of 0.6-0.80, 0.80-1 and close to 1 indicate moderate (but still acceptable), good and strong reliability,

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respectively (29). The standard error of measurement (SEM), which represents the random 2 variation (error) in a measure on repeated assessments, was calculated as √(𝜎𝑜2 + 𝜎𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙 ) (30).

An SEM value < 10% of the score range was considered small (31). To assess convergent validity, we calculated Spearman rank correlation coefficients to examine the association between the total BI and mRS score and UPDRS-ADL, SE, PDQ-39 (ADL) and BBS scores. Coefficients <0.30, 0.30-0.70, and >0.7 were considered weak, moderate and strong, respectively (32). Discriminant

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validity was examined by the Wilcoxon test to compare ON and OFF medication phases (33). P<0.05 was considered statistically significant. Results Demographic and clinical characteristics of the 260 participants are in Table 1: 187 (71.9%) were males and the mean (SD) age was 60.3 (12.3) years. The mean BI was 94.0 (12.6) in the ON

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medication phase and 80.0 (23.3) in the OFF phase and the mean mRS score was 1.85 (0.98) and

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2.66 (1.23), respectively (Table 2). Acceptability

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The floor effect for both scales (BI and mRS) in ON and OFF phases was in the acceptable range

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(0%) (Table 2). The ceiling effect in both medication phases was in the acceptable range (0%) for the mRS but not the BI (ON phase= 47.7%; OFF phase= 32.7%). Also, the skewness for the BI

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and mRS in both ON and OFF phases was satisfactory overall. Dimensionality

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For the BI, the EFA extracted one component in the ON phase (eigenvalue = 4.54; Kaiser-Meyer-

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Olkin = 0.80; Bartlett’s test of sphericity = 620.29; p<0.0001) and 2 components (autonomic function and self-care) in the OFF phase (eigenvalue = 5.09; Kaiser-Meyer-Olkin = 0.89; Bartlett’s

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test of sphericity = 657.35; p<0.0001) (Table 3). Reliability

For the BI, the Cronbach α values for ON and OFF phases were lower than but close to acceptable for clinical application (0.85 and 0.88 vs 0.9) (Table 2). The inter-item correlations were 0.21 to 0.76 in the ON phase and 0.21 to 0.65 in the OFF phase, which indicates acceptable correlation between BI items (Table 4). The ICCs for the total BI and mRS score for test–retest were 0.84 (95% CI 0.78-0.91) and 0.86 (95% CI 0.80-0.91) in the ON phase and 0.77 (95% CI 0.65-0.85) and 0.86 (95% CI 0.78-0.91) in 8 Page 8 of 13

the OFF phase (Table 2). Inter-rater reliability for the total BI and mRS score were good in the ON phase (BI: ICC=0.91, 95% CI 0.87-0.94; mRS: ICC=0.83, 95% CI 0.77-0.88) and OFF phase (BI: ICC=0.90, 95% CI 0.88-0.93; mRS: ICC=0.85, 95% CI 0.79-0.89). The SEM values were low for the BI (ON: 3.41, OFF: 9.90) and mRS (ON: 0.33, OFF: 0.45). Convergent validity The total BI showed moderate to high correlation with the UPDRS-ADL, SE, PDQ-39 (ADL),

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BBS and mRS scores in the ON phase (ρ =0.51-0.68) and OFF phase (ρ =0.71-0.74)(Table 5). Also, for both phases, we found a moderate to high correlation (ρ =0.48-0.82) between the mRS

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and SE, UPDRS-ADL, PDQ-39 (ADL) and BBS scores.

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Discriminant validity

We found a significant difference between ON and OFF medication phases for the total mean (SD)

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BI (ON: 94.0 [12.6]; OFF: 80.0 [23.3]; Wilcoxon test, Z= -7.64; P<0.0001) and mRS (ON: 1.9 [1.0]; OFF: 2.7 [1.2]; Z= -7.98; P<0.0001).

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Discussion

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The current study aimed at determining the psychometric properties of the BI and mRS during ON and OFF medication phases in idiopathic PD. The results suggest that the BI and mRS have good

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reliability and validity in both medication phases for PD. The acceptability analysis revealed a moderate ceiling effect for the BI in both phases. This finding may be due to less disease progression in our participants (mostly stage 1 to 3 based on the Hoehn and Yahr classification), thereby leading to high scores in the BI. This result agreed with previous studies in other populations (34-36). The high ceiling effect must be taken into account because it could challenge the use of this tool in assessments and intervention planning. The mRS acceptability was in an acceptable range as in previous studies in stroke survivors (37).

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The EFA results for BI differed in ON and OFF medication phases. In the ON phase, the measurement items resulted in one factor. Previous studies of diverse neurological conditions also found one factor for BI (38-41). However, in the OFF phase, items 1 (bowel) and 2 (bladder) were loaded in one factor (autonomic function), whereas typical basic ADLs loaded on a different factor (self-care). This finding may be explained by decreased ability because of the medication effect on movement, but bladder and bowel control are autonomic functions that can represent “non-motor

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fluctuations”, whose pathophysiological mechanisms and relationships with the dopaminergic treatment differ from the motor impairment (42). So far and to our knowledge, no studies have

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examined the factor structure of the BI in the OFF phase.

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Internal consistency of the BI in both medication phases agreed with former studies. The present study suggests acceptable to good test–retest and inter-rater reliability in both ON and OFF phases,

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which also agrees with previous studies in PD (9, 10, 20, 35). The SEM values in the ON and OFF phases for the BI and mRS were less than 10% of the score range, which suggests that these scales

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have sufficient accuracy in both medication phases and agrees with the Hsieh et al. study (43).

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The strength of correlation of the BI with UPDRS-ADL, SE, PDQ-39 (ADL), BBS and mRS scores was moderate in the ON phase and high in the OFF phase, which suggests that the BI is consistent

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with other tools for assessing disability in a PD population. This finding agrees with the Morley et al. and Shulman et al. studies for the ON phase (8, 11). The correlation of the mRS score with SE, UPDRS-ADL, PDQ-39 (ADL) and BBS scores was moderate to high in both medication phases. So far, no studies have compared this scale to other scales in a PD population. The results of discriminant validity showed that both the BI and mRS have the ability to separate the level of disability in ADL during ON and OFF medication phases. Assessing functional limitations properly is important for monitoring the course of the disease and guiding decisions on clinical management (e.g., with deep brain stimulation or medication adjustments) (11). 10 Page 10 of 13

This study had several limitations. First, the levodopa dose was not calculated for each participant. Second, most of the participants had a mild or moderate level of PD (i.e., stage 1 to 3 in the Hoehn and Yahr scale). Thus, individuals with low disability were over-represented, which can decrease the possibility of discrimination between the participants. In addition, this study involved native Persian speakers, which limits the generalizability of the results to other populations with different

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languages.

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Conclusion

The present study suggests that the Barthel Index and modified Rankin scale, two widely used tools

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in other neurological diseases, have a good validity and reliability in PD in both ON and OFF

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medication phases. Better knowledge about these tools may contribute to improving their application and interpretation and, along with PD specific assessments, help with a more accurate

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evaluation of patients in research and clinical settings.

Acknowledgements. We thank the individuals with PD who kindly agreed to participate in this

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study. The study was funded by the Student Research Committee in the Iran University of Medical

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