Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS): Scale presentation and clinimetric testing results

EXPEDITED PUBLICATION

Research Article

Movement Disorder Society-Sponsored Revision of the Uniﬁed

Parkinson’s Disease Rating Scale (MDS-UPDRS): Scale

Presentation and Clinimetric Testing Results

Christopher G. Goetz,

Barbara C. Tilley,

Stephanie R. Shaftman,

Glenn T. Stebbins,

Stanley Fahn,

Pablo Martinez-Martin,

Werner Poewe,

Cristina Sampaio,

Matthew B. Stern,

Richard Dodel,

Bruno Dubois,

Robert Holloway,

Joseph Jankovic,

Jaime Kulisevsky,

Anthony E. Lang,

Andrew Lees,

Sue Leurgans,

Peter A. LeWitt,

David Nyenhuis,

C. Warren Olanow,

17,18

Olivier Rascol,

Anette Schrag,

Jeanne A. Teresi,

Jacobus J. van Hilten,

and Nancy LaPelle,

for the Movement Disorder Society UPDRS Revision Task Force

Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois

Biostatistics, Bioinformatics, and Epidemiology, Medical University of South Carolina, Charleston, South Carolina

Department of Neurology, Columbia University, New York, New York

Neuroepidemiology Unit and CIBERNED, Carlos III Institute of Health, Madrid, Spain

Department of Neurology, Innsbruck Medical University, Innsbruck, Austria

Department of Pharmacology, Faculdade de Medicina de Lisboa, Lisboa, Portugal

Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania

Department of Neurology, Philipps-University, Marburg, Germany

Department of Neurology, Ho

pital de la Salpe

trie

re, Paris, France

Department of Neurology, University of Rochester, Rochester, New York

Department of Neurology, Baylor College of Medicine, Houston, Texas

Department of Neurology and CIBERNED, Sant Pau Hospital, Barcelona, Spain

Division of Neurology, University of Toronto, Toronto, Canada

Reta Lila Weston Institute of Neurological Studies, University College, London, England

Department of Neurology, Wayne State University, Detroit, Michigan

Department of Neurology and Rehabilitation, University of Illinois, Chicago, Illinois

Department of Neurology, Mount Sinai School of Medicine, New York, New York

Department of Neuroscience, Mount Sinai School of Medicine, New York, New York

Laboratoire de Pharmacologie Me

dicale et Clinique, Toulouse University, Toulouse, France

Department of Clinical Neurosciences, University College, London, England

Stroud Center, Division of General Medicine and Psychiatric Institute, Columbia University, New York, New York

Department of Neurology, Leiden University, Leiden, The Netherlands

Division of Preventive and Behavioral Medicine, University of Massachusetts, Worcester, Massachusetts

Potential conﬂict of interest: All authors have conﬁrmed they have

no conﬂict of interest related to this effort.

Received 7 July 2008; Revised 23 August 2008; Accepted 3

September 2008

Published online 20 November 2008 in Wiley InterScience

(www.interscience.wiley.com). DOI: 10.1002/mds.22340

Additional Supporting Information may be found in the online

version of this article.

*Correspondence to: Dr. Christopher G. Goetz, Department of

Neurological Sciences, Rush University Medical Center, Suite 755,

1725 West Harrison Street, Chicago, IL 60612. E-mail: cgoetz@

rush.edu

2129

Movement Disorders

Vol. 23, No. 15, 2008, pp. 2129–2170

 2008 Movement Disorder Society

Abstract: We present a clinimetric assessment of the

Movement Disorder Society (MDS)-sponsored revision of the

Uniﬁed Parkinson’s Disease Rating Scale (MDS-UPDRS).

The MDS-UDPRS Task Force revised and expanded the

UPDRS using recommendations from a published critique.

The MDS-UPDRS has four parts, namely, I: Non-motor

Experiences of Daily Living; II: Motor Experiences of Daily

Living; III: Motor Examination; IV: Motor Complications.

Twenty questions are completed by the patient/caregiver.

Item-speciﬁc instructions and an appendix of complementary

additional scales are provided. Movement disorder specialists

and study coordinators administered the UPDRS (55 items) and

MDS-UPDRS (65 items) to 877 English speaking (78% non-Lat-

ino Caucasian) patients with Parkinson’s disease from 39 sites.

We compared the two scales using correlative techniques and

factor analysis. The MDS-UPDRS showed high internal consis-

tency (Cronbach’s alpha 5 0.79–0.93 across parts) and corre-

lated with the original UPDRS (q 5 0.96). MDS-UPDRS across-

part correlations ranged from 0.22 to 0.66. Reliable factor struc-

tures for each part were obtained (comparative ﬁt index > 0.90

foreachpart),whichsupporttheuseofsumscoresforeachpart

in preference to a total score of all parts. The combined clinimet-

ric results of this study support the validity of the MDS-UPDRS

for rating PD.  2008 Movement Disorder Society

Key words: Parkinson’s disease; rating scales; UPDRS;

clinimetrics

The Uniﬁed Parkinson’s Disease Rating Scale

(UPDRS) was originally developed in the 1980s

and

has become the most widel y used clinical rating scale

for Parkinson’s disease (PD).

In 2001, the Movement

Disorder Society (MDS) sponsored a critique of the

UPDRS, and this document lauded the strengths of the

scale but identiﬁed a numb er of ambiguities, weak-

nesses, and areas in need of inclusion to reﬂect current

scientiﬁc developments.

The summary conclusions

recommended the development of a new version of the

UPDRS that would retain the strengths of the original

scale, but resolve identiﬁed problems and especially

incorporate a number of clinically pertinent PD-related

problems poorly captured in the original version. Based

on this critique, the MDS commissioned a revision of

the scale, resulting in a new version, termed the MDS-

sponsored UPDRS revision (MDS-UPDRS).

This

scale successfully passed initial clinimetric testing

and

was therefore submitted to a large-scale comparison

with the original UPDRS. This report presents the

MDS-UPDRS for the ﬁrst time in published form and

the clinimetric testing results of this large-scale pro-

gram among native English speaking PD patients.

MDS-UPDRS (Table 1): The primary areas of revi-

sion were discussed in a prior publication.

First,

whereas the original four component (Parts I–IV)

design was retained, the focus of each part has been

changed, and the data acquisition methodology has

been both clariﬁed and modiﬁed. Part I concerns ‘‘non-

motor experiences of daily living,’’ Part II concerns

‘‘motor exper iences of daily living ,’’ Part III is retained

as the ‘‘motor examination,’’ and Part IV concerns

‘‘motor complications.’’ Several questions from Part I

and all questions from Part II have been designed to

be amenable to a patient/caregiver questionnaire format

and therefore can be completed without the investiga-

tor’s input. For the remaining Part I questions that deal

with complex behaviors and all questio ns in Part IV

that deal with motor ﬂuctuations and dyskinesias, the

investigator is required to conduct the interview. Part

III retains the objective assessments of parkinsonism,

but all tasks now have speciﬁc instructions. Rater

involvement time for administering the MDS-UPDRS

is estimated to require less than 10 min for the inter-

view items of Part I, 15 min for Part III, and 5 min for

Part IV, resulting in an equivalent rater time invest-

ment to the original scale and meeting the 30-min

goal. The remaining questionnaire items are answered

by the patient or caregiver and, other than supervision,

do not involve rater time. Whereas the detailed assess-

ments still prioritize the motor aspects of PD, the

screening questions on nonmotor elements are designed

to capture both the presence and severity of clinically

pertinent problems in this domain.

Each question is anchored with ﬁve responses that

are linked to commonly accepted clinical terms: 0 5

normal, 1 5 slight, 2 5 mild, 3 5 moderate, and 4 5

severe. After each clinical descriptor, a short text fol-

lows, which describes the criteria for each response.

Whereas each response is tailored to the question, the

progression of disability or impairment is based on a

consistent infrastructure. ‘‘Slight’’ (1) refers to symp-

toms/signs with sufﬁciently low frequency or intensity

to cause no impact on function; ‘‘mild’’ (2) refers to

symptoms/signs of frequency or intensity sufﬁcient to

cause a modest impact on function; ‘‘moderate’’ (3) refers

to symptoms/signs sufﬁciently frequent or intense to

impact considerably, but not prevent, function; ‘‘severe’’

(4) refers to symptoms/signs that prevent functi on.

The full MDS-UPDRS contains questions/evalua-

tions (Table 1), divided across Part I (13), Part II (13),

Part III (33 scores based on 18 items, several with

right, left or other body distribution scores), and Part

IV (6). The MD S-UPDRS rates 65 items in comparison

2130 C.G. GOETZ ET AL.

Movement Disorders, Vol. 23, No. 15, 2008

TABLE 1. Conceptual mapping of items and scores from the original UPDRS to the MDS-UPDRS

MDS-UPDRS item Original UPDRS item

General concepts for mapping ratings from the original UPDRS to

MDS-UPDRS (UPDRS?MDS-UPDRS)

Part I In the MDS-UPDRS, the conceptual construct focuses on the impact

rather than the presence of symptoms, and whereas there is a general

parallelism between UPDRS and MDS-UPDRS, this emphasis needs

to be considered at all times by the rater and/or patient.

Cognitive impairment Intellectual impairment General conceptual comparison, although the emphasis is different in the

two versions: 0?0; 1?2 (option 1 on MDS-UPDRS is new and not

captured in original scale); 2?3; 3?4; 4?4

Hallucinations and psychosis Though disorder 0?0; 1?0 (vivid dreams not part of this question in MDS-UPDRS);

2?1or2;3?3; 4?4

Depressed mood Depression General conceptual comparison, although the emphasis is different in the

two versions: 0?0; 1?1; 2?2; 3?3; 4?4

Anxious mood

New item: No comparison

Apathy Motivation/initiative General conceptual comparison, although the emphasis is different in the

two versions: 0?0; 1?1; 2?2; 3?3; 4?4

Features of dopamine

dysregulation syndrome

New item: No comparison

Nighttime sleep problems

Sleep disturbances 0?0; 1 on UPDRS could be 0 (if the patient had only daytime

sleepiness) or any of the available ratings on the MDS-UPDRS

Daytime sleepiness

Sleep disturbances 0?0; 1 on UPDRS could be 0 (if the patient had only nighttime sleep

problems) or any of the available ratings on the MDS-UPDRS

Pain and other sensations Sensory complaints

related to parkinsonism

General conceptual comparison, although the emphasis is different in

the two versions: 0?0; 1?1; 2?2; 3?3; 4?4

Urinary problems

New item: No comparison

Constipation problems

New item: No comparison

Lightheadedness on standing

Symptomatic orthostasis 0?0; 1?1,2,3,4 depending on severity

Fatigue

New item: No comparison

Part II As in Part I, for the MDS-UPDRS, the conceptual construct focuses on

the impact rather than the presence of symptoms, and whereas there

is a general parallel between UPDRS and MDS-UPDRS, this

emphasis needs to be considered at all times by the rater and/or

patient.

Speech Speech 0?0; 1?1; 2?2, 3?3, 4?4

Salivation and drooling Salivation 0?0; 1?2 (option 1 on MDS-UPDRS new and not captured in original

scale; 2?3; 3?3; 4?4

Chewing and swallowing Swallowing General conceptual comparison, although the emphasis is different in the

two versions: 0?0; 1?3 (options 1 and 2 on MDS-UPDRS are new

and not captured well by the original scale); 2?3; 3?2; 4?4

Eating tasks Cutting food and

handling utensils

0?0; 1?1; 2?2; 3?3; 4?4

Dressing Dressing 0?0; 1?1; 2?2; 3?3; 4?4

Hygiene Hygiene Although MDS-UPDRS focuses on all tasks and does not limit questions

to tasks mentioned in UPDRS, general parallelism exists for the two:

0?0; 1?1; 2?2; 3?3; 4?4

Handwriting Handwriting The MDS-UPDRS emphasizes clarity of writing, not size, but a general

parallelism exists for the two scales: 0?0; 1?1; 2?1; 3?2or3;

4?4

Doing hobbies and

other activities

New item: No comparison

Turning in bed Turning in bed and

adjusting bed clothes

The MDS-UPDRS emphasizes regularity of help needed, but a general

parallelism exists for the two scales: 0?0; 1?1; 2?2or3;3?3or

4; 4?4

Tremor Tremor The MDS-UPDRS emphasizes interference from tremor, but a general

parallelism exists for the two scales: 0?0; 1?1; 2?2; 3?3; 4?4

Getting out of bed, car,

or deep chair

New item: No comparison

Walking and balance Walking 0?0; 1?1; 2?1or2;3?3or4;4?4

Freezing Freezing when walking Conceptually, the focus of the MDS-UPDRS is different from the

UPDRS because the need for assistance is emphasized in the MDS-

UPDRS rather than the consequence (falls) that will depend on

availability of help. Only partial parallelism can be drawn on this

question: 0?0; 1?1; 2?2,3,or 4; 2?2, 3, or 4; 4?2, 3, or 4

Falls This item is not part of the MDS-UPDRS because it is not a normal

‘‘experience of daily living.’’ Falling is assessed in Part III

2131MDS-UPDRS: CLINIMETRIC ASSESSMENT

Movement Disorders, Vol. 23, No. 15, 2008

to 55 on the original UPDRS, 48 that had 0 to 4

options and 7 with yes/no responses.

Nine new items in the MDS-UPDRS were not cap-

tured in any form on the original scale: anxious mood,

dopamine dysregulation syndrome, urinary problems,

constipation, fatigue, doing hobbies, getting in and out

of bed, toe tapping, and freezing (objective rating).

Lightheadedness was assessed in the original UPDRS

as present or absent, but in the MDS-UPDRS, the

symptom is assessed with the 0 to 4 rating system.

Nighttime sleep problems and daytime sleepiness are

assessed in the MDS-UPDRS and the yes/no sleep dis-

TABLE 1. (Continued )

MDS-UPDRS item Original UPDRS item

General concepts for mapping ratings from the original UPDRS to

MDS-UPDRS (UPDRS?MDS-UPDRS)

Part III

Speech Speech 0?0; 1?1; 2?2; 3?3or4;4?4

Facial expression Facial expression 0?0; 1?1; 2?2; 3?3; 4?4

Rigidity of neck and

four extremities

Rigidity Conceptually, the focus of the question has been changed to emphasize

resistance to passive movement with greater clarity. Partial parallelism can

be suggested: 0?0; 1?1; 2?2; 3?2; 4?3; 4 rating on the MDS-UPDRS

is not captured by the original UPDRS

Finger taps

Finger taps The original UPDRS had descriptors (mild, moderate, severe), that ﬁt better

with the current designations of slight, mild and moderate, creating

difﬁculties with a direct parallelism, but the task descriptions allow

parallelism: 0?0; 1?1or2;2?2or3;3?3; 4?4

Hand movements

Hand movements See ‘‘ﬁnger taps’’ for explanation: 0?0; 1?1or2;2?2or3;3?3; 4?4

Pronation/supination

Pronation/supination See ‘‘ﬁnger taps’’ for explanation: 0?0; 1?1or2;2?2or3;3?3; 4?4

Toe tapping

New item; no comparison

Leg agility

Leg agility See ‘‘ﬁnger taps’’ for explanation: 0?0; 1?1or2;2?2or3;3?3; 4?4

Arising from chair Arising from chair 0?0; 1?1; 2?2; 3?3; 4?4

Gait Gait 0?0; 1?1; 2?2; 3?3or4;4?4

Freezing of gait

New item: no comparison from original scale

Postural stability Postural stability 0?0; 1?1or2;2?3; 3?4; 4?4

Posture Posture 0?0; 1?1; 2?2or3;3?4; 4?4

Global spontaneity of

movement

Body bradykinesia 0?0; 1?1; 2?2; 3?3; 4?4

Postural tremor of hands

a,b

Action/postural

tremor

The MDS-UPDRS separates these two forms of tremor and focuses only on

amplitude, so there is no parallelism between the original and new versions

Re-emergent tremor is rated as part of postural tremor (see Discussion)

Kinetic tremor of hands

a,b

Action/postural

tremor

Rest tremor amplitude

The MDS-UPDRS separates two features of rest tremor (amplitude and

consistency), so there is no parallelism between the original and new versions

Constancy of rest tremor

New item: no comparison. Tremor consistency was considered in original

UPDRS but combined with amplitude, making the assessment ambiguous

Part IV

Time spent with

dyskinesia

Dyskinesia duration 0?0; 1?1; 2?2; 3?3; 4?4

Functional impact

of dyskinesias

MDS-UPDRS provides written anchors whereas the UPDRS uses only ‘‘mild,

moderate, severe, marked.’’ 0?0; 1?2 (option 1 on MDS-UPDRS new and

not captured in original scale); 2?3; 3?4; 4?4

Time spent in the

OFF state

Off duration 0?0; 1?1; 2?2; 3?3; 4?4

Functional impact

of ﬂuctuations

New item: no comparison. Written to run in parallel with Function impact of

dyskinesias

Complexity of motor

ﬂuctuations

Offs predictable

(yes/no) Offs

unpredictable

(yes/no) Offs

sudden (yes/no)

MDS-UPDRS consolidates concepts covered by several yes/no questions on

UPDRS. There is no simple mapping for this reason

Painful OFF-state dystonia Presence of early

morning dystonia

(yes/no)

0?0; 1?1, 2, 3, or 4

Many items have shifted emphasis with the MDS-UPDRS, but this guide shows the general concept behind the two scoring systems and can be

used as a reference. The mapping table is a guide and not recommended as an automatic transfer for scores from one scale to the other. Gray box

marks items covered by patient/caregiver questionnaire without direct input from the investigator.

Domains not previously assessed with 0 to 5 ratings.

Items with right and left measurements.

2132 C.G. GOETZ ET AL.

Movement Disorders, Vol. 23, No. 15, 2008

turbances option is replaced from the original UPDRS.

The question on Complexity of Motor Fluctuations in

the MDS-UPDRS merges the three yes/no questions

related to predicable, unpredictable, and sudden OFF

period from the UPDRS. In regards to tremor, the orig-

inal Action/Postural Tremor question has been divided

into two questions focusing on each component of

tremor separ ately. For rest tremor, whereas the UPDRS

combined amplitude and constancy of tremor into its

descriptors, on the MDS-UPDRS the severity ratings

for each body part concern only the amplitude and a

separate question rates the constancy.

Direct item-to-item mapping from the original

UPDRS to the MDS-UPDRS was not envisioned to be

possible, because the two scales were not conceptually

identical. Nonetheless, because the new version was

directly based on the original scale, a number of paral-

lels and guidelines were utilized in the construction of

the MDS-UPDRS. For some questions, the insertion of

slight/mild/moderate/severe was sufﬁcient to realign

the rating options. In some cases, however, because the

original scale often used ‘‘mild/moderate/severe/

marked’’ the former rating of 1 (mild) now could be

separated into two choices (slight 1 or mild 2) in the

MDS-UPDRS. In such cases, the former moderate

scores (2) advanced to 3 in the MDS-UPDRS and the

former severe (3) and marked (4) were collapsed into

one option (severe 4) in the MDS-UPDRS. In other

cases, adjustments in the mid-ranges (2 and 3) were

felt to be necessary in order to maintain a consistent

conceptual framework of slight/mild/moderate/severe

in the MDS-UPDRS. This decision to shift from mild/

moderate/severe/marked to slight/mild/moderate/severe

as the scale’s clinical construct was anchored in two

concepts: ﬁrst, that many clinical trials focus on early

PD where change among scores of normal, slight, and

mild problem s are important to document; and, second,

that at the high range of impairment or disability (for-

merly severe and marked), functional differences may

not be clinical ly relevant. Another conceptual anchor

of the MDS-UPDRS, especially apparent in Parts I, II,

and IV was the progressing disability from none (0) to

a perception of the problem without interference (slight

1), to interference with isolated activity (mild 2), to in-

terference with normal activity (moderate 3), to preclu-

sion of normal activity (severe 4). This process was

not utilized consistently in the original UPDRS,

although parallels could be constructed between the

two versions in many cases. Yes/no questions from the

original Part IV were reformatted and reﬁned to ﬁt the

0 to 4 rating format of the rest of the scale in the

MDS-UPDRS, so that a partial parallelism between the

two versions could be mapped. New items that

assessed features not assessed in the original UPDRS

could not have any mapping possibility from the origi-

nal scale. With these caveats, general mapping patterns

between the two scales were outlined to allow a guide

to raters making the transition between the UPDRS

and the MDS-UPDRS, but were not constructed with

the aim of allowing automatic substitution (Table 1).

As part of the clinimetric plan, however, a review of

score ranges for each part of the MDS-UPDRS was

planned to be tested against the original version (see

below).

ON and OFF deﬁnitions are provided to ensure uni-

formity among raters and the score sheet documents the

ON/OFF status associated with the Part III assessment.

For Parts I and II, the ofﬁcial scale will not separate ON

from OFF, but, for special studies, the same questions can

be asked separately for ON or OFF periods. Throughout

the MDS-UPDRS, speciﬁc instructions are provided to

enhance a uniform application. Finally, questions have

been written to be culturally sensitive and applicable to

patients of different ethnic and social backgrounds.

As an ongoing process, at the end of the MDS-

UPDRS, clinicians and researchers are directed to an

Appendix of Additional Scales. This portion of the

MDS-UPDRS is not considered a static document, but,

instead, it will be updated as deemed appropriate by

the MDS Task Force of Rating Scales for PD (see

Supp. Info. Appendix 1 for listing of scales). This ap-

pendix is designed to direct clinicians and research

investigators to scales that cover in greater detail the

components of the MDS-UPDRS that are only assessed

with single items. The Task Force has previously pub-

lished assessments of scales for depression and psychosis,

and others are planned.

5,6

These assessments use a stand-

ard set of criteria to establish Recommended and Sug-

gested scales in an effort to encourage reporting in a con-

sistent manner and to facilitate comparisons among dif-

ferent reports. For items that have not had ofﬁcial Task

Force reports, the subcommittee of the MDS-UPDRS

dedicated to the Appendix has reviewed scales using the

same criteria (Cristina Sampaio, chairperson).

CLINIMETRIC TESTING PROGRAM

Methods

Based on successful prelimi nary testing,

the MDS-

UPDRS validation program was designed to test the

scale’s intrinsic attributes, including internal consis-

tency, factor structure, differential item functioning,

and its comparability with the original UPDRS.

2133MDS-UPDRS: CLINIMETRIC ASSESSMENT

Movement Disorders, Vol. 23, No. 15, 2008

We recruited movement disorder specialists and

experienced study coordinators to examine PD patients

with both scales. Special attention was focused on

recruitment of diverse race/ethnicity representations.

Native English speakers (both raters and patients) par-

ticipated. To complete separate clinimetric analyses

within each racial/ethnic group, a minimal sample size

of 650 per racial/ethnic group was desirable assuming

that at least 10 observations per item were required.

After obtaining individual IRB approval, each partici-

pating site recruited patients to under go both the

UPDRS and MDS-UPDRS in a single setting. Partici-

pation was based on a commitment to rate between 10

and 20 subjects who covered the range of mild to

severe PD, based on clinical judgment. Scores were

sent to a central database electronically and veriﬁed

for completeness. Queries were resolved between the

statistical center and individual raters, and once com-

pleted, a given case was entered into the full data set

and double-checked for accuracy.

Statistical Analyses

To describe patient demographics, we computed

means, standard deviations, and ranges. To assess rela-

tionships between the new and original version, we com-

puted Pearson’s correlations between the MDS-UPDRS

and the UPDRS for total score and for each part. Corre-

lations were computed to assess the relationships among

the parts of the MDS-UPDRS. As a measure of internal

consistency (reliability), Cronbach’s alpha was calculated

for each part. Further, ﬂoor and ceiling effects were

examined by calculating the percentage of lowest and

highest possible scores for each part. Mplus v. 4.21

was

used for the factor analysis using polychoric correlations

because of the ordinal nature of the data.

The factor analysis was run in two parts. An explor-

atory factor analysis (EFA), informed by eigenvalues

and Scree plots, was used to determine the number of

factors that best represents the data. A factor loading

cutoff of 0.40 was used to determine those items to

retain in a factor. As a second step, a conﬁrmatory fac-

tor analysis (CFA) was used in the assessment of

dimensionality, with a comparative ﬁt index (CFI) ‡

0.90 deﬁned as an acceptable ﬁt. If the CFI was less

than 0.90, each factor was examined to identify poorly

behaved items, i.e., those with high loadings on more

than one factor.

Based on the review of the items and

the model ﬁt statistics, additional EFAs and CFAs

were run. The process was repeated until the most par-

simonious model was found with a CFI ‡ 0.90. We

assessed the entire scale as a single factor structure,

each part as a separate set of factors, and all combina-

tions of parts.

Results

Patient Sample

A total of 877 native English-speaking PD patients

were examined with the UPDRS and MDS-UPDRS

(560 men and 317 women). There were 682 non-Lat-

ino Caucasians and 195 (22%) of other race/ethnicity,

speciﬁcally 49 African Americans, 87 Latinos, 1 native

Hawaiian, 43 Asians, and 15 with other race/ethnic-

ities. All Hoehn and Yahr stages were represented, with

the majority of patients being stages II (stage I 5 63,

stage II 5 467, stage III 5 174, stage IV 5 109, stage

V 5 53, missing 11). The mean age of the cohort was

68.2 years (SD: 10.8; range: 31–98), and the mean PD

duration was 8.3 years (SD: 6.7; range: 0–40 years).

Fifty-seven patients were not treated with antiparkinso-

nian medications. A total of 685 patients were treated

with levodopa in combination with another symptomatic

treatment for PD, 115 patients were on symptomatic

therapy without levodopa, 5 patients were on levodopa

alone, and 15 had missing treatment information. Motor

ﬂuctuations were observed in 483 patients and 304

patients had dyskinesia. A total of 723 were examined

in the ON state and 99 in the OFF state, while ON/OFF

information was not recorded for 55 patients.

Rater Sample

There were 69 raters from 39 English-speaking treat-

ment centers (USA, 32; Canada, 2; UK, 5) who eval-

uated patients with the original and MDS-UPDRS

instruments (see listing at end of manuscript). All

raters were physicians or nurse coordinators regularly

working with PD patients, regularly using the UPDRS

for clinical care or research purposes, and all were

recruited through the MDS. Raters were instructed to

perform the UPDRS in their standard manner and to

use the MDS-UPDRS following the instructions em-

bedded in the new scale for each item. The choice of

patients was left to the raters, but emphasis was placed

by the Task Force team on recruitment of a maximal

number of patients who were of a race/ethnicity other

than non-Latino Caucasian with a full breadth of Hoehn

and Yahr stages. The mean number of cases subm itted by

each rater was 11.4 (SD: 8.2; range: 1–29).

Clinimetric Proﬁle of MDS-UPDRS

Internal consistency was computed for each of the

MDS-UPDRS parts [Part I (13 item s), alpha 5 0.79;

2134 C.G. GOETZ ET AL.

Movement Disorders, Vol. 23, No. 15, 2008

Part II (13 items), alpha 5 0.90; Part III (33 items),

alpha 5 0. 93; Part IV (6 items), alpha 5 0.79]. Mean

scores (SD) for each part were: Part I: 11.5 (7.0); Part

II: 16.0 (10.0); Part III: 36.8 (18.4); Part IV: 4.0 (4.2).

The distributions of the total scores in the MDS-

UPDRS and original UPDRS were similar: UPDRS

mean: 61.0 (SD: 30.3), covering 55 items; MDS-

UPDRS mean: 68.4 (SD: 32.8), covering 65 items. The

MDS-UPDRS showed strong concurrent validity based

on high correlations between the two scales (total score

r 5 0.96), as well as between the individual parts of

the two scales: [Part I, r 5 0.76; Part II, r 5 0.92; Part

III, r 5 0.96; Part IV (sum of items 32–39 covering

dyskinesias and motor ﬂuctuations on the UDPRS vs.

total Part IV from the MDS-UPDRS), r 5 0.89]. As a

measure of internal validity, correlations among the

MDS-UPDRS parts were examined. These analyses

conﬁrmed that each part assesses a different aspect of

PD, with mos t parts, except Parts I and II, having rela-

tively low correlations (Parts I and II, r 5 0.67; Parts I

and III, r 5 0.43; Parts I and IV, r 5 0.39; Parts II

and IV, r 5 0.44; Parts III and IV, r 5 0.22). As

anticipated, Parts II and III that covered patient percep-

tions of motor function and the objective examination

were more highly correlated (r 5 0.66). Our analysis

for possib le ﬂoor and ceiling effects demonstrated a

low percentage of lowest and highest scores for Parts I

TABLE 2. Factor structures of the four

parts of the MDS-UPDRS

Factor Item Item factor loading

Part I: Nonmotor aspects of experiences of daily living (CFI 5 0.94,

RMSEA 5 0.06)

Factor 1 Percent variance 5 32.7

Daytime sleepiness 0.57

Sleep problems 0.40

Cognitive impairment 0.48

Pain and other sensations 0.48

Hallucinations and psychosis 0.40

Urinary problems 0.59

Constipation problems 0.49

Features of DDS 0.49

Light headedness on standing 0.45

Fatigue 0.54

Factor 2 Percent variance 5 9.8

Depressed mood 0.83

Anxious mood 0.66

Apathy 0.53

Part II: Motor aspects of experiences of daily living (CFI 5 0.95,

RMSEA 5 0.09)

Factor 1 Percent variance 5 53.0

Speech 0.79

Saliva and drooling 0.45

Chewing and swallowing 0.60

Handwriting 0.45

Doing hobbies and other activities 0.45

Factor 2 Percent variance 5 8.7

Eating tasks 0.68

Tremor 0.43

Factor 3 Percent variance 5 7.7

Dressing 0.64

Hygiene 0.64

Turning in bed 0.65

Getting out of bed 0.73

Walking and balance 0.82

Freezing 0.76

Part III: Motor examination (CFI 0.91, RMSEA 5 0.10)

Factor 1 Percent variance 5 36.8

Speech 0.59

Facial expression 0.53

Arising from chair 0.77

Gait 0.87

Freezing of gait 0.83

Postural stability 0.81

Posture 0.70

Global spontaneity of movement 0.64

Factor 2 Percent variance 5 15.1

Rest tremor amplitude, RUE 0.72

Rest tremor amplitude, LUE 0.71

Rest tremor amplitude, RLE 0.73

Rest tremor amplitude, LLE 0.71

Rest tremor amplitude, lip/jaw 0.59

Constancy of rest tremor 0.88

Factor 3 Percent variance 5 6.4

Rigidity, neck 0.67

Rigidity, RUE 0.73

Rigidity, LUE 0.74

Rigidity, RLE 0.80

Rigidity, LLE 0.81

Factor 4 Percent variance 5 6.1

Finger tapping, right hand 0.67

Hand movements, right hand 0.66

Pronation/supination, right 0.68

TABLE 2. (Continued )

Factor Item Item factor loading

Factor 5 Percent variance 5 4.8

Finger tapping, left hand 0.69

Hand movements, left hand 0.72

Pronation/supination movements, left 0.65

Factor 6 Percent variance 5 4.6

Postural tremor, right hand 0.66

Postural tremor, left hand 0.72

Kinetic tremor, right hand 0.81

Kinetic tremor, left hand 0.80

Factor 7 Percent variance 5 3.3

Toe tapping, right foot 0.65

Toe tapping, left foot 0.63

Leg agility, right leg 0.64

Leg agility, left leg 0.62

Part IV: Motor complications (CFI 5 1.0, RMSEA 5 0.05)

Factor 1 Percent variance 5 63.6

Time spent in the OFF state 0.87

Functional impact of ﬂuctuations 0.84

Complexity of motor ﬂuctuations 0.83

Painful OFF state dystonia 0.49

Factor 2 Percent variance 5 15.6

Time spent with dyskinesias 0.72

Functional impact of dyskinesias 0.94

CFI, comparative ﬁt index; RMSEA, root mean square error of

approximation.

2135MDS-UPDRS: CLINIMETRIC ASSESSMENT

Movement Disorders, Vol. 23, No. 15, 2008

to III: Part I, lowest 0.1%/highest 0.8%; Part II, lowest

0.1%/highest 0.7%; Part III, lowest 0.1%/highest 0.2%.

In the case of Part IV, covering the presence and severity

of motor complications, there was an expected ﬂoor

effect, but no ceiling effect: lowest 36.7%/highest 0.1%.

(see Supp. Info. Appendix 2 for histograms of each part).

Factor Structure

Exploratory testing of the combined four parts of the

MDS-UPDRS did not identify a single factor structure

that could be conﬁrmed (CFI 5 0.74). A factor struc-

ture combining Parts II and III was explored, but could

not be conﬁrmed. Several items had salient loadings on

more than one factor and some items did not load on

any factor. A factor structure was also explored for the

combination of Parts II to IV. A factor structure with

12 factors was identiﬁed by the EFA; however, the CFI

was <0.90, too low to provide conﬁrmation. As seen

earlier, several items had salient loadings on more than

one factor, and some items did not load on any factor.

These combined results preclude using a total MDS-

UPDRS score or scores based on combinations of parts.

We then analyzed the MDS-UPDRS parts individu-

ally (see Supp. Info. Appendix 3 for Scree plots). This

analysis and the conﬁrmatory analysis identiﬁed a fac-

tor structure that was statistically consistent (CFI for

each part was >0.90) and clinically meaningful (Ta-

ble 2) for all parts. For Part I (CFI 5 0.94), two

factors were identiﬁed, one covering depression, anxi-

ety, and apathy and the other covering the other non-

motor functions (shared variance 5 42.5%). For Part II

(CFI 5 0.95), three factors were identiﬁed, one cover-

ing several ﬁne motor functions, one covering tremor

and eating tasks, and one focusing on several large

motor functions (shared variance 5 69.4%). For Part

III (CFI 5 0.91), seven factors were identiﬁed: midline

function, rest tremor, rigidity, bradykinesia right upper

extremity, bradykinesia left upper extremity, postural

and kinetic tremors, and lower limb bradykinesia

(shared variance 77.1%). For Part IV (CFI 5 1.0), two

factors were identiﬁed, one focusing on ﬂuctuations

including off-state dystonia and the other on dyskine-

sias (shared variance 5 79.2%). Intercorrelations

among factors for each part ranged from 0.04 to 0.71,

indicating both unique and shared information provided

by the different factors.

DISCUSSION

The MDS-UPDRS was designed to be more compre-

hensive than the ori ginal UPDRS, with new items

devoted to several nonmotor elements of PD.

3,4

The

choice of the new items was based on input from the

Task Force committee members, patient groups, and

MDS members. Based on the published critique of the

UPDRS,

the ﬁve-point range for each item was

retained, and clinical anchors of normal (0), slight (1),

mild (2), moderate (3), and severe (4) were added to

provide a consistency across item s. Importantly, the

MDS-UPDRS places greater emphasis on distinguish-

ing relatively mild impairments and disabilities,

drawing distinctions between slight and mild, whereas

former distinctions between severe and marked are

now collapsed into the severe rating (4). This decision

was anchored in the realities that clinical trials are

focusing increasingly on early disease, and functional

differences betwee n severe and marked impairments

from the original scale may not be clinically relevant.

As a result of this decision, for several items in the

MDS-UPDRS, moderate impairment and disability is

now rated as 3 instead of 2.

An important addition to the MDS-UPDRS is a set

of detailed instructions. Because the MDS-UDPRS is

envisioned to be the primary international rating scale

for PD clini cal care and research, an emphasis was

placed on clear and detailed descriptions of methods

for data acquisition. These are ofﬁcially part of the

scale, so that international colleagues can perform rat-

ings in a systematic manner within and across centers.

The instructions are intended to standardize the method

of application of the scale so that the MDS-UPDRS

data are collected uniformly. The scale has not yet

been translated into non-English editions, and this

effort will start in 2008 through the MDS. A clinimet-

ric program for each language edition is planned and

the Task Force will offer statistical assistance.

The MDS-UPDRS involves participa tion by patients

and caregivers for the assessment of several nonmotor

and motor experiences of daily living. These questions

were written at seventh grade level and extensively

tested in patient focus groups. The question on fatigue

was included based on patient responses that this

symptom has a high impact on health-re lated quality of

life and was not otherwise captured in the scale.

Because cogni tive impairments frequently occur in

PD, the questionnaire was designed to be completed by

the patient alone, with the input of caregivers, or by

the caregiver alone, depending on patient/caregiver

preference.

Given the number of items to be assessed in the

MDS-UPDRS, the patient sample required for adequate

statistical analysis was large. We were, however, suc-

cessful in recruiting colleagues internationally from

2136 C.G. GOETZ ET AL.

Movement Disorders, Vol. 23, No. 15, 2008

English-speaking centers to help in this important

effort. These colleagues were able to identify and

examine PD patients across the spectrum of disabilities.

Investigators were asked to select a gamut of severities

among PD patients and to be attenti ve to obtaining di-

versity in gender and race/ethnicity. The distribution of

this data set in terms of disease severity, drug treatme nt,

gender, and ethnic balance should not be considered to be

representative of the investigators’ overall practice popu-

lation, because the composition reﬂects an effort to have

a clinically reasonable number of cases in different cate-

gories to test the clinimetric properties of the scale. None-

theless, the majority of patients were Hoehn and Yahr

stages II and III, a pattern seen in cross-sectional analyses

in early, mid, and late disease.

Based on the wide range

of severities sampled and the distribution of high and low

scores within each part, we are conﬁdent that the MDS-

UPDRS is not limited by ﬂoor or ceiling effects.

We placed special emphasis on the recruitment of

subjects of diverse race/ethnicity. Although we did not

achieve our goal of 650 per racial/ethnic group, we did

succeed in involving a much higher perc entage of sub-

jects of race/ethnicity other than non-Latino Caucasian

(N 5 195, 22% of our total sample) than the usual 0%

to 10% reported in clinical trials (personal communica-

tion, M. Schneider and C. Swearingen). Other than

non-Latino Caucasians, we did not have enough partic-

ipants in any one racial or ethnic group to conduct sta-

tistical analyses within any speciﬁc subgr oup. Efforts

to enhance diversity in clinical trials of PD is a focus

of US government funding,

and this program demon-

strates that PD investigators are able to excee d current

performance in clinical trials. To continue to enhance

this data set, the statistical center for the program (e-

mail: ti[email protected]) will continue to accept addi-

tional ratings of the UPD RS vs. MDS-UPDRS for

those patients other than non-Latino Caucasians.

The clinimetric analysis supports the reliability and

validity of the MDS-UPDRS. It performs extremely

well in comparison with the original version with high

internal consistency for the entire scale as well as high

internal consistency on each part. In addition, even

though restructured, each part of the MDS-UPDRS

correlates highly with the corresponding part of the

original scale. The scaling modiﬁcations and item addi-

tions to the MDS-UPDRS provide new informat ion

while still capturing the features of PD from the origi-

nal scale. On the other hand, because the item

responses (0, 1, 2, 3, 4) have been substantially modi-

ﬁed in terms of wording and concept, we cannot pro-

vide an algorithm with point-to-point or summary con-

version numbers.

The technique of factor analysis is a particularly

strong clinical/s tatistical method for scale evaluation,

because it tests whether items cluster and allows clini-

cians to determine if these clusters fall into compo-

nents that represent clinically relevant domains. Fur-

thermore, it allows statistical assessment of whether

the clusters correlate and thereby capture information

about the overall entity being studied, in this case, PD.

The MDS-UPDRS has excellent factor validity, and

the factor analysis conﬁrms that the items cluster in

clinically pertinent domains. Because data are collected

using three different methods, some based exclusively

on patient or caregiver responses (questionnaire), some

based solely on the investigator’s assessments (motor

examination), and some with a combination (complex

behaviors and motor complications), we did not antici-

pate that the total score (combined Parts I–IV) would

likely be a recommended outcome. Although the high

correlation between the total scores on the original

UPDRS and MDS-UPDRS demonstrates that the two

scales are measuring the same overall entity of PD, the

MDS-UPDRS factor analysis conﬁrmed that neither

the combined parts nor combinations based on differ-

ent acquisition methods have a stable factor structure.

However, when each part is considered separately, the

factor structures are both clinimetrically sound and

clinically pertinent. In this light, we recommend that

each of the parts (I–IV) should be reported separately

and not collapsed into a sing le ‘‘Total MDS-UPDRS’’

summary score.

Comparing the factor structure of Part III of the

MDS-UPDRS to published factor analyses of the origi-

nal UPDRS,

the MDS-UPDRS identiﬁes lower limb

bradykinesia as a new factor, likely because of the

addition of toe tapping as a separate rating. Attention

was directed to separating postural from kinetic tremor,

and extensive discussion within the group focused on

the placement of ‘‘reemergent rest tremor.’’ Because

reemergent tremor interferes with the holding of

objects against gravity, this tremor was relegated to

postural tremor.

Despite these deliberations, the fac-

tor structure identiﬁed postural and kinetic tremors as a

single factor and the rest tremor was distinct from this

factor.

The ﬁnal step in the clinimetric analysis will involve

an assessment of differential item function (DIF).

Although this type of analysis was never performed on

the original UPDRS, our large sample size and avail-

able statistical programs will allow this level of scru-

tiny for all items. DIF is deﬁned as group differences

in item response, conditional on the state or trait

assessed. As an example, if in two groups deﬁned by

2137MDS-UPDRS: CLINIMETRIC ASSESSMENT

Movement Disorders, Vol. 23, No. 15, 2008

gender, one rarely endorsed a high score for an item,

while the other often endorsed a high score, but the

two had similar scores on the overall part, this differ-

ence suggests that gender has an inﬂuence on the item

interpretations or responses. DIF may be due to group

differences in neurological burden, comp rehension, ad-

aptation, or bias. There are two types of DIF: uniform

and nonuniform. Uniform DIF is present when item

thresholds differ between the groups, but the slopes are

parallel on the item characteristic curves. Nonuniform

DIF is present when the two curves do not follow a

linear progression acro ss the rating options. The pres-

ence of either form of DIF would suggest that the item

in question does not perform the same in different

groups of the patient sample. We plan to examine three

patient characteristics for the DIF analysis in our study

sample: gender, race/ethnicity, and age. If DIF is identi-

ﬁed, future modiﬁcations will be considered and tested

in subsequent phases of our clinimetric program (see

below). In this light, although we present the MDS-

UPDRS for immediate application in clinical settings,

we emphasize that the scale will continue to be evaluated

and that further reﬁnements may develop in the future

based on additional and ongoing clinimetric analyses.

The Appendix of Additional Scales is ofﬁcially part

of the MDS-UPDRS and directs clinicians and

researchers to scales that focus in more detail on areas

of disability that are considered as single-item ques-

tions on the MDS-UPDRS. The MDS Task Force on

Rating Scales in PD has initiated a number of critiques

of availab le scales dealing with different areas of dys-

function, and rankings of Recommended and Suggested

have been developed using predeﬁned criteria.

5,6

The

results of these reports have been supplemented by

assessments by the MDS -UPDRS subcommit tee dedi-

cated to the Appendix and, as new clinimetric reports

on scales are publishe d and new scales are introduced,

the Appendix will be updated. Because the nonmotor

aspects of PD are an increasing focus of clinical deci-

sion-making and research, we recommend a uniform

selection of scales so that differ ent reports can be com-

pared with similar measures.

The next steps in the MDS-UPDRS program include

the non-English translations, testing the MDS-UDPRS

for responsivity to change over time, and analysis of

questions with DIF. The planned clinimetric program

leaves several additional projects available for investi-

gator-initiated research. Correlations between the

MDS-UPDRS and other scales such as quality of life

measures or global disease burden scales that are not

speciﬁc for PD are encouraged by the authors, but are

not part of this core program. Future clinical trials in

PD will tend to be of longer duration (often 5 years or

longer) as new therapies are tested to delay progression

post-levodopa administration. The long duration makes

it unlikely that the participant in a trial will have the

same rater at every visit. Thus, it is important that tem-

poral stability, sensitivity to change, and interrater reli-

ability be established in the MDS-UPDRS. To facilitate

interrater reliability, a Teaching Tape, modeled after

the one developed for the motor section of the original

UPDRS, is being developed.

The MDS-UPDRS is available on the MDS web site

(www.movementdisorders.org). Likewise, the Appen-

dix of Additional Scales is also available electronically

and will be updated through the MDS web site.

Acknowledgments: The MDS received unrestricted grants

for the development of the UPDRS revision program from

Boehringer-Ingelheim (USA), GlaxoSmithKline, and Pﬁzer,

Inc. The UK Parkinson’s Disease Society also provided sup-

port for assessment of subjects in the United Kingdom. Fund-

ing was also provided by the NINDS U01NS043127. We and

the MDS acknowledge the work of the following colleagues

whose data formed the core of the clinimetric comparison

between the UPDRS and MDS-UPDRS: Pinky Agarwal,

Saima Athar, Yvette Bordelan, Helen M. Bronte-Stewart,

Richard Camicioli, Kelvin Chou, Wendy Cole, Arif Dalvi,

Holly Delgado, Alan Diamond, Jeremy P. Dick, John Duda,

Rodger J. Elble, Carol Evans, Virgilio G. Evidente, Hubert

H. Fernandez, Susan Fox, Joseph H. Friedman, Robin D.

Fross, David Gallagher, Christopher G. Goetz, Deborah Hall,

Neal Hermanowicz, Vanessa Hinson, Stacy Horn, Howard

Hurtig, Un Jung Kang, Galit Kleiner-Fisman, Olga Klepit-

skaya, Katie Kompoliti, Eugene C. Lai, Maureen L. Leehey,

Iracema Leroi, Kelly E. Lyons, Terry McClain, Steven W.

Metzer, Janis Miyasaki, John C. Morgan, Martha Nance,

Joanne Nemeth, Rajesh Pahwa, Sotirios A. Parashos, Jay S.

Schneider, Anette Schrag, Kapil Sethi, Lisa M. Shulman,

Andrew Siderowf, Monty Silverdale, Tanya Simuni, Mark

Stacy, Matthew B. Stern, Robert Malcolm Stewart, Kelly

Sullivan, David M. Swope, Pettaruse M. Wadia, Richard W.

Walker, Ruth Walker, William J. Weiner, Jill Wiener, Jayne

Wilkinson, Joanna M. Wojcieszek, Summer Wolfrath, G.

Frederick Wooten, Allen Wu, Theresa A. Zesiewicz, Richard

M. Zweig.

Author Roles: All authors participated in MDS-UPDRS

design, clinimetric analysis, interpretation of results, and

manuscript writing. Dr. Goetz worked with the MDS to pro-

cure funding. Statistical analysis was conducted by Barbara

Tilley, Stephanie Shaftman, and Glenn Stebbins with input

from all other authors.

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