Validation of the MDS clinical diagnostic criteria for Parkinson's disease

BACKGROUND

In 2015, the International Parkinson and Movement Disorder Society published clinical diagnostic criteria for Parkinson's disease. These criteria aimed to codify/reproduce the expert clinical diagnostic process and to help standardize diagnosis in research and clinical settings. Their accuracy compared with expert clinical diagnosis has not been tested. The objectives of this study were to validate the International Parkinson and Movement Disorder Society diagnostic criteria against a gold standard of expert clinical diagnosis, and to compare concordance/accuracy of the International Parkinson and Movement Disorder Society criteria to 1988 United Kingdom Brain Bank criteria.

METHODS

From 8 centers, we recruited 626 parkinsonism patients (434 PD, 192 non-PD). An expert neurologist diagnosed each patient as having PD or non-PD, regardless of International Parkinson and Movement Disorder Society criteria (gold standard, clinical diagnosis). Then a second neurologist evaluated the presence/absence of each individual item from the International Parkinson and Movement Disorder Society criteria. The overall accuracy/concordance rate, sensitivity, and specificity of the International Parkinson and Movement Disorder Society criteria compared with the expert gold standard were calculated.

RESULTS

Of 434 patients diagnosed with PD, 94.5% met the International Parkinson and Movement Disorder Society criteria for probable PD (5.5% false-negative rate). Of 192 non-PD patients, 88.5% were identified as non-PD by the criteria (11.5% false-positive rate). The overall accuracy for probable PD was 92.6%. In addition, 59.3% of PD patients and only 1.6% of non-PD patients met the International Parkinson and Movement Disorder Society criteria for clinically established PD. In comparison, United Kingdom Brain Bank criteria had lower sensitivity (89.2%, P = 0.008), specificity (79.2%, P = 0.018), and overall accuracy (86.4%, P < 0.001). Diagnostic accuracy did not differ according to age or sex. Specificity improved as disease duration increased.

CONCLUSIONS

The International Parkinson and Movement Disorder Society criteria demonstrated high sensitivity and specificity compared with the gold standard, expert diagnosis, with sensitivity and specificity both higher than United Kingdom Brain Bank criteria. © 2018 International Parkinson and Movement Disorder Society.

Missing Data in the Unified Dysksinesia Rating Scale (UDysRS)

Objective

Identify the number of allowable missing values still permitting valid surrogate score calculation for the Unified Dyskinesia Rating Scale (UDysRS).

Background

Missing data frequently occur in Parkinson's disease rating scales, and they compromise data validity, risking data exclusion from final analyses.

Methods

Accessing the International Parkinson and Movement Disorder Society-sponsored UDysRS translation databases (3313 complete scores). We sequentially removed item scores, consistently or randomly from subjective and objective sections. Lin's Concordance Correlation Coefficient compared prorated scores with complete scores. We considered prorated scores valid when Coefficients exceeded 0.95.

Results

For consistently missing items, three from the subjective section and five from the objective section are allowable. For randomly missing items, seven from the subjective section and four from the objective section are permissible.

Conclusions

We provide guidelines for constructing valid surrogate summary UDysRS scores with clear thresholds for retaining or rejecting scores based on missing values.

Rating Scales and Performance-based Measures for Assessment of Functional Ability in Huntington's Disease: Critique and Recommendations

Limitation of functional ability is a major feature of Huntington's disease (HD). The International Parkinson and Movement Disorder Society (MDS) commissioned the appraisal of the use and clinimetric properties of clinical measures of functional ability that have been applied in HD studies and trials to date, to make recommendations regarding their use based on standardized criteria. After a systematic literature search, we included a total of 29 clinical measures grouped into two categories: (1) performance-based measures (e.g., balance, walking, and reaching/grasping), and (2) rating scales. Three performance-based measures are rated as "recommended": the Tinetti Mobility Test for screening of fall risk and for severity assessment of mobility in patients with manifest HD (up to stage III); the Berg Balance Scale for severity of balance impairment; and the Six-Minute Walk Test for assessment of walking endurance (severity) in HD subjects with preserved ambulation. No rating scale targeting functional ability reached a "recommended" status either for screening or severity measurement. The main challenges identified in this review include applying widely accepted conceptual frameworks to the identified measures, the lack of validation of clinical measures to detect change over time, and absence of validated measures for upper limb function. Furthermore, measures of capacity or ability to perform activities of daily living had ceiling effects in people with early and pre-manifest HD. We recommend that the MDS prioritize the development of new scales that capture small, but meaningful changes in function over time for outcome assessment in clinical trials, particularly in earlier stages of HD.

Relationship between the MDS-UPDRS and Quality of Life: A large multicenter study of 3206 patients

BACKGROUND

The relationship between Health-Related Quality of Life (HRQoL) and MDS-UPDRS has not been fully studied so far. The aim of this study was to evaluate the relationship between all MDS-UPDRS components and HRQoL in a representative international cohort of PD patients.

METHODS

We collected demographic and disease-related data as well as MDS-UPDRS and PDQ8 scales. Data were analyzed using correlations between PDQ8 and all MDS-UPDRS items, subsequently two hierarchical multiple regressions were performed, first between the scores of the MDS-UPDRS Parts and PDQ8 and second between individual items from those Parts demonstrating significant relationship to PDQ8 scores in the first regression. LASSO regression analyses were performed to evaluate the relationship between PDQ8 and all individual MDS-UPDRS items.

RESULTS

A total of 3206 PD patients were included in the study. In the first regression analysis, PDQ8 was significantly related to MDS-UPDRS parts I and II, but not to III and IV. In the second regression model, significant contributions to PDQ8 were found for Part I items Fatigue, Pain, Depressed mood, Apathy; and Part II items Dressing, Doing hobbies, Freezing, Speech and Tremor. In the LASSO analysis, six Part I, seven Part II, three Part III and one Part IV items contributed to PDQ8 scores. The five items most significantly related to the model were Depressed mood, Dressing, Apathy, Pain and Fatigue.

CONCLUSIONS

This is so far the largest study related to HRQoL issues in PD. Restrictions in activities of daily living and non-motor symptoms significantly contribute to HRQoL in PD.

Quality of Life in Huntington's Disease: Critique and Recommendations for Measures Assessing Patient Health-Related Quality of Life and Caregiver Quality of Life

The compromise of quality of life in Huntington's disease is a major issue, both for individuals with the disease as well as for their caregivers. The International Parkinson and Movement Disorder Society commissioned a review of the use and clinimetric validation status of measures used in Huntington's disease to assess aspects related with quality of life and to make recommendations on their use following standardized criteria. We included both patient-centered measures (patient health-related quality-of-life measures) and caregiver-centered measures (caregiver quality-of-life measures). After conducting a systematic literature search, we included 12 measures of patient health-related quality of life and 2 measures of caregiver quality of life. Regarding patient-centered measures, the Medical Outcomes Study 36-Item Short-Form Health Survey is "recommended" as a generic assessment of health-related quality of life in patients with Huntington's disease. The 12-Item Short Form Health Survey, the Sickness Impact Profile, the 12-item World Health Organization Disability Assessment Schedule, and the Huntington's Disease Health-Related Quality of Life questionnaire are "suggested." No caregiver-centered quality-of-life measure obtained a "recommended" status. The Alzheimer's Carer's Quality of Life Inventory and the Huntington's Disease Quality of Life Battery for Carers are "suggested." Recognizing that the assessment of patient health-related quality of life can be challenging in Huntington's disease, as patients may lack insight and there is insufficient clinimetric testing of these scales, the committee concluded that further validation of currently available health-related quality-of-life measures should be undertaken, namely, those Huntington's disease-specific health-related quality-of-life measures that have recently been reported and used. © 2018 International Parkinson and Movement Disorder Society.

Rating Scales for Motor Symptoms and Signs in Huntington's Disease: Critique and Recommendations

Motor symptoms are a major feature of Huntington's disease (HD). The International Parkinson and Movement Disorder Society (MDS) commissioned the assessment of the clinimetric properties of motor rating scales in HD to make recommendations regarding their use, following previously established standardized criteria. After a systematic literature search, a total of 6 rating scales assessing motor symptoms and signs in HD were included for review. Performance testing (reviewed elsewhere) and quantitative motor rating methods were excluded. Only the Unified Huntington's Disease Rating Scale-Total Motor Score (UHDRS-TMS) was classified as "recommended" for assessing the severity of motor signs in HD. The following scales were classified as "suggested": Abnormal Involuntary Movement Scale, the UHDRS-TMS4, the Quantified Neurological Examination, and the Marsden and Quinn Chorea Severity Scale. The committee also concluded that further assessment of existing rating scales, including the UHDRS-TMS, is necessary to determine sensitivity to change and to screening for the presence of motor signs specific to HD. There is also a need to develop a motor rating scale to be used in positive gene carriers with subtle but not definite motor signs.

Rating scales for cognition in Huntington's disease: Critique and recommendations

Cognitive impairment is one of the main features of Huntington's disease and is present across the disease spectrum. As part of the International Parkinson's Disease and Movement Disorder Society-sponsored project to review all clinical rating scales used in Huntington's disease, a systematic review of the literature was performed to identify cognitive scales used in Huntington's disease and make recommendations for their use. A total of 17 cognitive scales were identified and evaluated. None of the scales met criteria for a "recommended" status. For assessing severity of cognitive dysfunction, the Montreal Cognitive Assessment was "recommended with caveats." The UHDRS Cognitive Assessment, the UHDRS-For Advanced Patients cognitive section, the Alzheimer's Disease Assessment Scale-Cognitive Subscale, the Frontal Assessment Battery, the Mattis Dementia Rating Scale, the Mini-Mental State Examination, and the Repeatable Battery for the Assessment of Neuropsychological Status were "suggested" for evaluating severity of cognitive impairment. The MoCA was "suggested" as a screening tool for cognitive impairment. The major challenge in the assessment of cognition in Huntington's disease is the lack of a formal definition of dementia and/or mild cognitive impairment in this disease. The committee concluded that there is a need to further validate currently available cognitive scales in Huntington's disease, but that it is premature to recommend the development of new scales. Recently developed Huntington's disease-specific scales, such as the Huntington's Disease-Cognitive Assessment Battery, hold promise but require the completion of more comprehensive clinimetric development. © 2017 International Parkinson and Movement Disorder Society.

Global scales for cognitive screening in Parkinson's disease: Critique and recommendations

BACKGROUND

Cognitive impairment is a common nonmotor manifestation of Parkinson's disease, with deficits ranging from mild cognitive difficulties in 1 or more of the cognitive domains to severe dementia. The International Parkinson and Movement Disorder Society commissioned the assessment of the clinimetric properties of cognitive rating scales measuring global cognitive performance in PD to make recommendations regarding their use.

METHODS

A systematic literature search was conducted to identify the scales used to assess global cognitive performance in PD, and the identified scales were reviewed and rated as "recommended," "recommended with caveats," "suggested," or "listed" by the panel using previously established criteria.

RESULTS

A total of 12 cognitive scales were included in this review. Three scales, the Montreal Cognitive Assessment, the Mattis Dementia Rating Scale Second Edition, and the Parkinson's Disease-Cognitive Rating Scale, were classified as "recommended." Two scales were classified as "recommended with caveats": the Mini-Mental Parkinson, because of limited coverage of executive abilities, and the Scales for Outcomes in Parkinson's Disease-Cognition, which has limited data on sensitivity to change. Six other scales were classified as "suggested" and 1 scale as "listed."

CONCLUSIONS

Because of the existence of "recommended" scales for assessment of global cognitive performance in PD, this task force suggests that the development of a new scale for this purpose is not needed at this time. However, global cognitive scales are not a substitute for comprehensive neuropsychological testing. © 2017 International Parkinson and Movement Disorder Society.

Turkish Standardization of Movement Disorders Society Unified Parkinson's Disease Rating Scale and Unified Dyskinesia Rating Scale

Background

Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and Unified Dyskinesia Rating Scale (UDysRS) were developed as standard tools to rate Parkinson's disease (PD) and drug-induced dyskinesias of PD. As these scales have become widely used, there is a need for translation to non-English languages. Here we present the standardization for the Turkish translations.

Methods

The scales were translated into Turkish and then back-translated to English. These back-translations were reviewed by the MDS team. After cognitive pretesting, movement disorder specialists from nine centers tested 352 patients for MDS-UPDRS, and 250 patients for UDysRS. Confirmatory factor analyses (CFAs) were used to determine if the factor structures for the reference standards could be confirmed in the Turkish data. The comparative fit indexes (CFIs) for the scales were required to be 0.90 or higher. Exploratory factor analyses (EFAs) were conducted to explore the underlying factor structure without the constraint of a pre-specified factor structure.

Results

For both scales, the CFIs were 0.94 or greater as compared to the reference standard factor structures. The factor structures were consistent with that of reference standards, although there were some differences in some areas as compared to the EFA of the reference standard dataset. This may be due to the inclusion of patients with different stages of PD and different cultural properties of raters and patients.

Conclusions

These results demonstrate that the Turkish translations of MDS-UPDRS and UDysRS have adequate clinimetric properties. They are established as the official translations and can be reliably used in Turkish speaking populations.

Validation of the Hebrew version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale

BACKGROUND

The Movement Disorders Society (MDS) published the English new Unified Parkinson's Disease Rating Scale (MDS-UPDRS) as the official benchmark scale for Parkinson's disease (PD) in 2008. We aimed to validate the Hebrew version of the MDS-UPDRS, explore its dimensionality and compare it to the original English one.

METHODS

The MDS-UPDRS questionnaire was translated to Hebrew and was tested on 389 patients with PD, treated at the Movement Disorders Unit at Tel-Aviv Medical Center. The MDS-UPDRS is made up of four sections. The higher the score, the worst the clinical situation of the patient is. Confirmatory and explanatory factor analysis were applied to determine if the factor structure of the English version could be confirmed in the Hebrew version.

RESULTS

The Hebrew version of the MDS-UPDRS showed satisfactory clinimetric properties. The internal consistency of the Hebrew-version was satisfactory, with Cronbach's alpha values 0.79, 0.90, 0.93, 0.80, for parts 1 to 4 respectively. In the confirmatory factor analysis, all four parts had high (greater than 0.90) comparative fit index (CFI) in comparison to the original English MDS-UPDRS with high factor structure (0.96, 0.99, 0.94, 1.00, respectively), thus confirming the pre-specified English factor structure. Explanatory factor analysis yielded that the Hebrew responses differed from the English one within an acceptable range: in isolated item differences in factor structure and in the findings of few items having cross loading on multiple factors.

CONCLUSIONS

The Hebrew version of the MDS-UPDRS meets the requirements to be designated as the Official Hebrew Version of the MDS-UPDRS.

Differential item functioning in the Unified Dyskinesia Rating Scale (UDysRS)

OBJECTIVE

Test if differential item functioning due to gender, age, race/ethnicity, or education impacts Unified Dyskinesia Rating Scale scores.

BACKGROUND

Testing rating scales for differential item functioning is a core validation step. If differential item functioning exists, interpretation of item scores must consider secondary influences on dyskinesia ratings.

METHODS

Using Unified Dyskinesia Rating Scale translation databases (N = 3,132), we tested uniform and nonuniform differential item functioning. We required confirmation by two independent methods and considered differential item functioning pertinent if McFadden pseudo R² magnitude statistics exceeded negligible ratings.

RESULTS

No age, race/ethnicity, or education nonuniform differential item functioning was identified. Gender nonuniform differential item functioning occurred for 2 items, both with negligible magnitude. Gender, race, and education uniform differential item functioning was observed for multiple items, all with negligible magnitude.

CONCLUSIONS

The Unified Dyskinesia Rating Scale items effectively capture dyskinesia severity without pertinent gender, age, race/ ethnicity, or education influence. © 2017 International Parkinson and Movement Disorder Society.

Charcot: Past and present

Jean-Martin Charcot (1825-1893) was the preeminent neurologist of the nineteenth century. Several of his major contributions remain fully relevant to contemporary neurology, and this essay highlights three areas of particular importance to the modern neurologist: the anatomo-clinical method that Charcot developed as the anchor of neurological study; the integration of new scientific discoveries from other fields as a core strategy for neurological advancement; and the role of heredity as the fundamental etiological focus to the understanding of the pathogenesis of primary neurological disorders. Further, Charcot left a strong tradition of visual skills as the core requirement for accurate neurological diagnosis and emphasized scientific humility in the face of difficult diseases. In spite of vast advances in neuroscience over the 20th and 21st centuries, the challenges faced by Charcot remain largely the same for the contemporary neurologist, and the lessons provided by Charcot retain their power and significance today.

Differences in MDS-UPDRS Scores Based on Hoehn and Yahr Stage and Disease Duration

Background

The Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) is a newly developed tool to assess Parkinson's disease (PD). Changes in scores on the scale over the course of PD, including increasing disease duration and Hoehn and Yahr (HY) stages, have not been described. The objectives of this study were to analyze MDS-UPDRS scores on Parts I through IV and their differences based on HY stage and disease duration in a large cohort of patients with PD.

Methods

For this cross-sectional study, demographic data and MDS-UPDRS scores were collected, including HY stage. Subscores on MDS-UPDRS Parts I through IV were analyzed using 1-way analyses of variance for each HY stage and in 5-year increments of disease duration. Part III (motor assessment) scores were analyzed separately for on and off states.

Results

The mean age of the 3206 patients was 65.8 ± 10.6 years, 53.3% were men, the mean disease duration was 11.5 ± 4.6 years, and the median HY stage was 2 (range, 0-5); 2156 patients were examined in an on state and 987 were examined in an off state. Scores for all MDS-UPDRS parts increased significantly through HY stages 1 through 5, with an average increase of 3.8, 7.7, 14.6, and 2.0 points consecutively for parts I through IV, respectively. For the 5-year increments of disease duration, MDS-UPDRS subscores increased by an average of 1.6, 3.3, 4.2, and 1.4 points consecutively for parts I through IV, respectively. This increase was significant only during the first 15 years of disease for all 4 parts, including part III scores evaluated in both on and off states.

Conclusions

MDS-UPDRS scores for all 4 parts increase significantly with every HY stage and also with 5-year increments of disease duration in the first 15 years of the disease.

Systematic review of severity scales and screening instruments for tics: Critique and recommendations

BACKGROUND

Several clinician, informant, and self-report instruments for tics and associated phenomena have been developed that differ in construct, comprehensiveness, and ease of administration.

OBJECTIVE

A Movement Disorders Society subcommittee aimed to rate psychometric quality of severity and screening instruments for tics and related sensory phenomena.

METHODS

Following the methodology adopted by previous Movement Disorders Society subcommittee papers, a review of severity and screening instruments for tics was completed, applying a classification as "recommended," "suggested," or "listed" to each instrument.

RESULTS

A total of 5 severity scales (Yale Global Tic Severity Scale, Tourette Syndrome Clinical Global Impression, Tourette's Disorder Scale, Shapiro Tourette syndrome Severity Scale, Premonitory Urges for Tics Scale) were "recommended," and 6 (Rush Video-Based Tic Rating Scale, Motor tic, Obsessions and compulsions, Vocal tic Evaluation Survey, Tourette Syndrome Global Scale, Global Tic Rating Scale, Parent Tic Questionnaire, Tourette Syndrome Symptom List) were "suggested." A total of 2 screening instruments (Motor tic, Obsession and compulsions, Vocal tic Evaluation Survey and Autism-Tics, Attention Deficit/Hyperactivity Disorder and Other Comorbidities Inventory) were "recommended," whereas 2 others (Apter 4-questions screening and Proxy Report Questionnaire for Parents and Teachers) were "suggested."

CONCLUSIONS

Our review does not support the need for developing new tic severity or screening instruments. Potential objectives of future research include developing a rating instrument targeting the full spectrum of tic-related abnormal behaviors, assessing/screening malignant forms of tic disorders, and developing patient-reported outcome measures. © 2017 International Parkinson and Movement Disorder Society.