CHAPTER 38: MOVEMENT DISORDER SOCIETY-UNIFIED PARKINSON’S DISEASE RATING SCALE (MDS-UPDRS)

Description

The Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) by Fahn et al. (1987) is a widely used comprehensive assessment of the severity of Parkinson’s disease (PD). Delivered through both an interview and self-report questionnaire, it is considered by many to be a gold standard of PD assessment. Revised in 2008 by the Movement Disorder Society (MDS), it assesses motor and non-motor experiences of daily living as well as motor complications which are thought to be hallmark symptoms of the disablement process posed by PD (Martínez-Martín et al., 2014). The MDS-UPDRS is composed of four subscales: (1) non-motor experiences of daily living (nMEDL); (2) motor experiences of daily living (M-EDL); (3) motor examination (MEx); and (4) motor complications (MCompl). The measure has 50 items scored along a 5-point Likert scale (0 to 4) with scoring descriptors varying for each item (Martínez-Martín et al., 2014). An example question relating to cognitive impairment is, “Over the past week have you had problems remembering things, following conversations, paying attention, thinking clearly, or finding your way around the house or in town?” which would be scored from (4) normal or no cognitive impairment to (0) severe cognitive dysfunction such that it precludes the patient’s ability to carry out normal activities and social interactions (Goetz et al., 2008). The MDS-UPDRS can be completed in 30 minutes with lower scores indicative of better performance.

Psychometrics

A study establishing the validity of the original version using 37 community-dwelling adults with PD found that test-retest reliability intra-class coefficients for all subtests as well as total scores were high with a range of r = 0.89 to 0.93, while internal consistency, as measured over 2 days, was moderate to good ranging from α = 0.66 to 0.89 (Steffen & Seney, 2008). Development research of the MDS-UPDRS using 877 subjects with PD showed high internal consistency across its parts with Cronbach’s alpha’s ranging from α = 0.79 to 0.93, while further results found a significant correlation with the original at 0.96 (Goetz et al., 2008). A study by Shulman et al. (2010) measuring the clinically important differences (CID), which is the amount of change in score needed for a client or clinician to recognize value, found that for minimal detectable change to occur 2.3 to 2.7 points were needed for the motor score and 4.1 to 4.5 was needed for the total score. A moderate change was considered 4.5 to 6.7 points (motor) and for the total score it was 8.5 to 10.3. A large CID was considered 10.7 to 10.8 points (motor) and 16.4 to 17.8 for the total score. Another study that involved an analysis of a sample of 435 Parkinson patients identified the following 3 factors that explained 70% of the variance of total scores:

1. Factor 1: The non-motor experiences of daily living composed of both rater and patient scores, as well as motor experiences of daily living (M-EDL) and its fluctuations.
   
2. Factor 2: Scores related to rigidity, bradykinesia and axial signs.
   
3. Factor 3: Included tremor and dyskinesia scores (Martínez-Martín et al., 2014).

The same study also found that the M-EDL domain was the most powerful determinant of health-related quality of life

Advantages

There is a good amount of research in support of the MDS-UPDRS assessment for use in both research as well as clinical practice and it can be obtained free of charge. The MDS also has a helpful interactive website devoted to this and other Parkinson assessments that the clinician may find useful.

Disadvantages

Although no special training is required, specific knowledge, skills, and terminology associated with PD are necessary where problems associated with those issues were highlighted in a study of inter-rater agreement between nurses and physicians using the original version that showed only moderate agreement between the two fields with an overall intra-class coefficient of 0.65 (Palmer et al., 2010). As for the question of whether all UPDRS-ME (motor exam) items were normal, there was agreement of only 0.53, suggesting that the UPDRS batteries may be complex to both administer and score (Palmer et al., 2010).

Administration

The MDS-UPDRS questionnaire has detailed instructions for scoring and administration provided in the examiner’s manual. The 50 questions that include elements of both rater and self-report items are scored along a 5-point scale (0 to 4) using various descriptors that roughly equate to (0) normal; (1) slight symptoms/signs with sufficiently low frequency or intensity to cause no impact on function; (2) mild symptoms/signs of frequency or intensity sufficient to cause a modest impact on function; (3) moderate symptoms/signs sufficiently frequent or intense to impact considerably, but not prevent, function; or (4) severe symptoms/signs that prevent function (Goetz et al., 2008).

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