Quantifying the impact of dyskinesias in PD: the PDYS-26: a patient-based outcome measure

Pulmonary function and medication effect in mild-stage subjects with Parkinson's disease

BACKGROUND

Parkinson's disease (PD) causes a series of movement disorders, many of them starting in the early stage.

OBJECTIVE

To analyze the pulmonary function of mild-stage subjects with PD and to investigate the effects of levodopa on it.

METHODS

We included 21 patients with idiopathic PD and 20 healthy control subjects. The participants were submitted to spirometry and impulse oscillometry assessments. The PD patients were evaluated during the "off" and "on" phases of their anti-PD medication, which was was converted to levodopa in an equivalent daily dose. A statistical analysis was performed with cross-sectional (PD patients "off" medication versus controls) and paired (PD patients "off" medication versus PD patients "on" medication) tests. The effect of levodopa was calculated with partial Eta-squared (η² _ρ). Significance was set at 5%.

RESULTS

The PD patients presented normal values in the impulse oscillometry. Regarding spirometry, the results indicated an incipient obstructive ventilatory disorder in the PD group - confirmed by patients' flow-volume curves. The PD patients received a daily dose of 354.7 ± 148.2 mg of levodopa. The paired analyses showed a small effect of anti-PD medication on pulmonary parameters (η² _ρ= 0.197 for spirometry and η² _ρ= 0.043 for impulse oscillometry).

CONCLUSION

Patients with PD in the mild stage of the disease present pulmonary compliance and resistance compatible with normal parameters. The differences regarding the spirometric results indicate an incipient obstructive ventilatory disorder in patients with PD. Levodopa had small effect on pulmonary function in the mild stage of the disease.

A New Evolutionary Algorithm-Based Home Monitoring Device for Parkinson's Dyskinesia

Parkinson's disease (PD) is a neurodegenerative movement disorder. Although there is no cure, symptomatic treatments are available and can significantly improve quality of life. The motor, or movement, features of PD are caused by reduced production of the neurotransmitter dopamine. Dopamine deficiency is most often treated using dopamine replacement therapy. However, this therapy can itself lead to further motor abnormalities referred to as dyskinesia. Dyskinesia consists of involuntary jerking movements and muscle spasms, which can often be violent. To minimise dyskinesia, it is necessary to accurately titrate the amount of medication given and monitor a patient's movements. In this paper, we describe a new home monitoring device that allows dyskinesia to be measured as a patient goes about their daily activities, providing information that can assist clinicians when making changes to medication regimens. The device uses a predictive model of dyskinesia that was trained by an evolutionary algorithm, and achieves AUC>0.9 when discriminating clinically significant dyskinesia.

Clinical Assessments in Parkinson's Disease: Scales and Monitoring

Measurement of disease state is essential in both clinical practice and research in order to assess the severity and progression of a patient's disease status, effect of treatment, and alterations in other relevant factors. Parkinson's disease (PD) is a complex disorder expressed through many motor and nonmotor manifestations, which cause disabilities that can vary both gradually over time or come on suddenly. In addition, there is a wide interpatient variability making the appraisal of the many facets of this disease difficult. Two kinds of measure are used for the evaluation of PD. The first is subjective, inferential, based on rater-based interview and examination or patient self-assessment, and consist of rating scales and questionnaires. These evaluations provide estimations of conceptual, nonobservable factors (e.g., symptoms), usually scored on an ordinal scale. The second type of measure is objective, factual, based on technology-based devices capturing physical characteristics of the pathological phenomena (e.g., sensors to measure the frequency and amplitude of tremor). These instrumental evaluations furnish appraisals with real numbers on an interval scale for which a unit exists. In both categories of measures, a broad variety of tools exist. This chapter aims to present an up-to-date summary of the most relevant characteristics of the most widely used scales, questionnaires, and technological resources currently applied to the assessment of PD. The review concludes that, in our opinion: (1) no assessment methods can substitute the clinical judgment and (2) subjective and objective measures in PD complement each other, each method having strengths and weaknesses.

Clinical Management of Drug-Induced Dyskinesia in Parkinson’s Disease: Why Current Approaches May Need to Be Changed to Optimise Quality of Life

Parkinson’s disease is a complex, progressive neurodegenerative disorder associated with both motor and non-motor symptoms. Current treatment strategies mainly target the alleviation of motor symptoms through dopaminergic replacement therapy. Many patients with Parkinson’s disease will eventually experience motor complications associated with their anti-parkinsonian medication. One of those complications is drug-induced dyskinesia. This paper firstly reviews current approaches to the management of drug-induced dyskinesia, from modifications to the titration of medication, to more invasive approaches like deep brain stimulation. Following this we describe a recent proposal suggesting that the treatment of dyskinesia should be based on the impact on daily activities of patients rather than on the mere presence of the condition. Next, we discuss how this approach could improve the quality of life of patients and their caregivers and finally, we suggest possible ways of implementing this approach in practice.

Parkinson's disease severity levels and MDS-Unified Parkinson's Disease Rating Scale

BACKGROUND

Severity of PD is usually assessed by means of the motor and disability-based Hoehn and Yahr staging (HY), or clinician and patient global perceptions. Scores of more detailed assessments, as the MDS-UPDRS, have not been translated to a grading that allows assignment of score sections to severity levels. The objective of the present study is to determine cut-off points for PD severity levels based on the MDS-UPDRS.

METHODS

International, observational study. Applied assessments were: HY, MDS-UPDRS, Clinical Impression for Severity Index, and Clinical and Patient Global Impression of Severity. The coincidence in severity level (mild, moderate, severe) of at least two clinical classifications plus the patient's gradation was considered "the criterion of severity". Cut-off values for each MDS-UPDRS subscale was determined by triangulation of: 1) percentile 90 of the subscale total score; 2) receiver operating characteristic (ROC) analysis; and 3) ordinal logistic regression (OLR) model.

RESULTS

Sample was composed of 452 consecutive PD patients without dementia, 55.3% males, age 65.1 ± 10.7 years and PD duration 8.7 ± 6.3 years. All HY stages were represented. The "criterion", classified 275 patients (60.8% of the sample) as: mild PD, 149 (54.2%); moderate, 82 (29.8%); and severe, 44 (16%). The following MDS-UPDRS cut-off points between mild/moderate and moderate/severe levels were found: Part 1: 10/11 and 21/22; Part 2: 12/13 and 29/30; Part 3: 32/33 and 58/59; and Part 4: 4/5 and 12/13.

CONCLUSION

Cut-off points to classify PD patients as mild, moderate, or severe on the basis of their MDS-UPDRS scores are proposed.

Stability of rating scale response category interpretations in neurological disorders

OBJECTIVES

Unambiguous use and interpretation of rating scale data assume that response categories are interpreted and work as intended. This study investigated the stability of interpretations of commonly used patient-reported rating scale response categories among people with neurological disorders.

MATERIALS AND METHODS

Forty-six people with neurological disorders (26 men; mean age, 57; Parkinson's disease, 50%; multiple sclerosis, 41%) indicated their interpretation of 21 response categories (representing frequencies, intensities and levels of agreement) on 100-mm visual analog scales (VAS) at two occasions, ≥2 weeks apart. Data were analyzed using intraclass correlation and weighted Kappa (ICC/Κw ; should be >0.4), mean/median differences, percentages agreement (PA), and the standard error of measurement (SEM).

RESULTS

Most response categories had ICC/Κw values <0.4. The overall average ICC/Κw was 0.279/0.294 (frequencies, 0.224/0.255; intensities, 0.265/0.251; levels of agreement, 0.362/0.376). The mean/median difference between time points across all 21 categories was 0.43/0.5 mm (mean/median absolute difference, 3.36/9 mm). The overall average PA and SEM were 6.5% and 16.1 mm, respectively.

CONCLUSIONS

Stabilities in interpretations of patient-reported rating scale response categories among people with neurological disorders were generally low. Categories expressing levels of agreement showed best results, suggesting that these may be preferable when appropriate with respect to the scale and its items. Future studies should consider response category interpretations in relation to various contexts. These observations suggest caution when interpreting raw rating scale data and argue for the use of modern rating scale methodologies such as the Rasch measurement model.

AFQ056 in Parkinson patients with levodopa-induced dyskinesia: 13-week, randomized, dose-finding study

AFQ056 is a novel, selective metabotropic glutamate receptor 5 antagonist. This was a 13-week, double-blind, placebo-controlled study. Patients with Parkinson's disease and moderate-to-severe levodopa (l-dopa)-induced dyskinesia who were receiving stable l-dopa/anti-parkinsonian treatment and were not currently receiving amantadine were randomized to receive either AFQ056 (at doses of 20, 50, 100, 150, or 200 mg daily) or placebo (1:1:1:1:2:3 ratio) for 12 weeks. The primary outcome was the modified Abnormal Involuntary Movements Scale. Secondary outcomes included the 26-item Parkinson's Disease Dyskinesia Scale, the Patient's/Clinician's Global Impression of Change, and the Unified Parkinson's Disease Rating Scale parts III (motor evaluation) and IV (severity of motor complications). Safety was assessed. In total, 98 of 133 (73.7%) AFQ056-treated patients and 47 of 64 (73.4%) patients in the placebo group completed the study. Baseline characteristics were comparable. Patients randomized to AFQ056 200 mg daily administered in 2 doses demonstrated significant improvements at Week 12 on the modified Abnormal Involuntary Movements Scale compared with placebo (difference, -2.8; 95% confidence interval [CI], -5.2, -0.4; P = 0.007). Based on final actual doses, there was a dose-response relationship on the modified Abnormal Involuntary Movements Scale, with 200 mg daily demonstrating the most robust effect (difference, -3.6; 95% CI, -7.0, -0.3; P = 0.012). Improvements in dyskinesia were supported by change on Unified Parkinson's Disease Rating Scale part IV item 32 (50 mg daily: difference, -0.7; 95% CI, -1.1, -0.2; P = 0.003; 200 mg daily: difference, -0.5; 95% CI, -0.8, -0.1; P = 0.005). No significant changes were observed on the 26-item Parkinson's Disease Dyskinesia Scale, the Unified Parkinson's Disease Rating Scale part IV item 33 or items 32 and 33, or the Patient's/Clinician's Global Impression of Change. Unified Parkinson's Disease Rating Scale part III scores were not significantly changed, indicating no worsening of motor symptoms. The most common adverse events (with incidence greater with AFQ056 than with placebo) were dizziness, hallucination, fatigue, nasopharyngitis, diarrhea, and insomnia. AFQ056 demonstrated anti-dyskinetic efficacy in this population without worsening underlying motor symptoms. These results will guide dose selection for future clinical trials.

Drug-induced dyskinesia in Parkinson's disease. Should success in clinical management be a function of improvement of motor repertoire rather than amplitude of dyskinesia?

BACKGROUND

Dyskinesia, a major complication in the treatment of Parkinson's disease (PD), can require prolonged monitoring and complex medical management.

DISCUSSION

The current paper proposes a new way to view the management of dyskinesia in an integrated fashion. We suggest that dyskinesia be considered as a factor in a signal-to-noise ratio (SNR) equation where the signal is the voluntary movement and the noise is PD symptomatology, including dyskinesia. The goal of clinicians should be to ensure a high SNR in order to maintain or enhance the motor repertoire of patients. To understand why such an approach would be beneficial, we first review mechanisms of dyskinesia, as well as their impact on the quality of life of patients and on the health-care system. Theoretical and practical bases for the SNR approach are then discussed.

SUMMARY

Clinicians should not only consider the level of motor symptomatology when assessing the efficacy of their treatment strategy, but also breadth of the motor repertoire available to patients.

Comparison of rating scales used to evaluate L-DOPA-induced dyskinesia in the 6-OHDA lesioned rat

Abnormal involuntary movement (AIM) rating scales are frequently used to study the mechanisms underlying L-DOPA-induced dyskinesia (LID) in 6-OHDA lesioned rodents and the propensity of novel treatments for Parkinson's disease to induce or alleviate similar abnormal behaviours. Despite the existence of at least one well validated method, other AIM scales are also in use. Moreover, there have been developments and variations in the original scales and their methods of use, without re-validation. In this study, 6-OHDA medial forebrain bundle lesioned Sprague-Dawley rats were treated with chronic L-DOPA 6 mg/kg/day for 5 weeks followed by 12 mg/kg/day for another 5 weeks. Rats were assessed weekly by simultaneous ratings on four published AIM and stereotypy scales with concurrent recording of rotation, over 3 hours following L-DOPA injection. Three contemporary AIM scales have then been validated pharmacologically using agents that are known to reduce LID clinically and in primates (amantadine) or to interfere with the activity of L-DOPA (the D(1) and D(2) dopamine receptor antagonists, SCH-23390 and raclopride) respectively. We also demonstrate that AIM, stereotypic and rotational behaviour are distinct motor dysfunctions induced by chronic and acute treatment of L-DOPA, and should be assessed separately. The undertaking of assessments at multiple time points is essential especially when testing the efficacy of new potential anti-dyskinetic treatments. Importantly critical to all AIM and rotation testing is the internal validation of both the scale being used and the environment being used.

l-Dopa-induced dyskinesia-clinical presentation, genetics, and treatment

Levodopa-induced dyskinesia (LID) has been recognized since the introduction of levodopa for the management of Parkinson's disease (PD) and continues to be one of the most clinically challenging factors in long-term management of patients with PD. Most patients develop LID within 10 years of PD onset and the cause has been attributed to various factors including disease demographics, pharmacological, and possibly genetic causes. The clinical pattern of LID varies and shows intra and inter-patient variability and has been classified based upon phenomenology and relation to timing of levodopa. The potential armamentarium to address and manage LID has significantly increased in the last decade. This chapter addresses the current understanding of various clinical aspects and available therapeutics for LID.

Impact of psychiatric symptoms and sleep disorders on the quality of life of patients with Parkinson's disease

The objective of this study is to assess how the non-motor symptoms of Parkinson's disease (PD), such as depression, cognitive deterioration, neuropsychiatric and sleep disorders, affect the quality of life, and to compare them with the motor symptoms in order to determine their real impact. A cross-sectional study was designed including 99 patients (mean age 68.5 ± 9.9 years, duration of disease 8.7 ± 6.2 years). Demographic data, onset of PD, years on treatment with levodopa (LD), class of dopaminergic drug prescribed, and dosages were obtained. The following scales were used: quality of life (PDQ-39), Unified Parkinson's Disease Rating Scale (UPDRS I-IV), Parkinson Disease Sleep Scale (PDSS) and daytime sleepiness (Epworth), Mini-Mental State Examination, depression (HAM-D), and the neuropsychiatric inventory (NPI-10). The PDQ-39 summary index (PDQ-39 SI) was 24.7 ± 13.2. A linear regression model including all variables showed that four independent variables accounted for 67.2% of the variance in the PDQ-39 SI (F = 33,277; p < 0.001): NPI, PDSS, UPDRS IV, and UPDRS I. When sub-items of the NPI, PDSS and UPDRS IV scales are analyzed, significant correlations (p < 0.001) are found between the PDQ-39 SI and depression, agitation, apathy, anxiety, hallucinations, delusions, incontinence of urine, morning painful posturing, restlessness in bed, morning fatigue, duration of off periods, unpredictable and predictable off periods, early morning dystonia, and sudden off periods. Neuropsychiatric symptoms, especially depression, nighttime sleep disorders such as urinary incontinence, nighttime restlessness, morning fatigue and somnolence, off-period dystonia and motor fluctuations are the variables that most affect the quality of life of patients with PD.

Objective measurement of dyskinesia in Parkinson's disease using a force plate

Clinical investigation of levodopa-induced dyskinesia (LID) in Parkinson's disease (PD) is limited because of lack of objective measurements and no consensus on use of a standard measuring tool. Currently, clinical trials use subject-completed diaries of dyskinesia throughout the day or investigator-administered clinical rating scales. An objective and valid method of measuring LID would reduce bias, variability, and decrease the time and number needed in trials of potential anti-dyskinetic agents. We have investigated using a force plate under standing subjects, which records movement of the center of pressure (CoP) to quantify LID over a levodopa (L-dopa) cycle. Twenty-two PD subjects (15 with LID, 7 without LID) admitted to an inpatient research facility had their PD meds withheld overnight, followed by a 2 hours intravenous L-dopa infusion the next day. The root mean squared of the velocity in the anterior-posterior direction (RMSV) derived from an analysis of the CoP, and, the modified Abnormal Involuntary Movement Scale (mAIMS) were performed repeatedly for 6 hours, initially as subjects were OFF before the infusion, through infusion until OFF again. There was a high correlation between the area under the curve (AUC) of the mAIMS and the RMSV within and between subjects. As a measure of LID, RMSV had excellent validity and reliability between subjects, and using a force plate was feasible. Sensitivity to changes in LID was initially demonstrated but should be repeated. Thus, CoP recordings on a force plate can objectively quantify LID in PD and may be very useful in clinical trials or other investigations of dyskinesia.

Interpretation of response categories in patient-reported rating scales: a controlled study among people with Parkinson's disease

BACKGROUND

Unambiguous interpretation of ordered rating scale response categories requires distinct meanings of category labels. Also, summation of item responses into total scores assumes equal intervals between categories. While studies have identified problems with rating scale response category functioning there is a paucity of empirical studies regarding how respondents interpret response categories. We investigated the interpretation of commonly used rating scale response categories and attempted to identify distinct and roughly equally spaced response categories for patient-reported rating scales in Parkinson's disease (PD) and age-matched control subjects.

METHODS

Twenty-one rating scale response categories representing frequency, intensity and level of agreement were presented in random order to 51 people with PD (36 men; mean age, 66 years) and 36 age-matched controls (14 men; mean age, 66). Respondents indicated their interpretation of each category on 100-mm visual analog scales (VAS) anchored by Never--Always, Not at all--Extremely, and Totally disagree--Completely agree. VAS values were compared between groups, and response categories with mean values and non-overlapping 95% CIs corresponding to equally spaced locations on the VAS line were sought to identify the best options for three-, four-, five-, and six-category scales.

RESULTS

VAS values did not differ between the PD and control samples (P = 0.286) or according to educational level (P = 0.220), age (P = 0.220), self-reported physical functioning (P = 0.501) and mental health (P = 0.238), or (for the PD sample) PD duration (P = 0.213) or presence of dyskinesias (P = 0.212). Attempts to identify roughly equally spaced response categories for three-, four-, five-, and six-category scales were unsuccessful, as the 95% CIs of one or several of the identified response categories failed to include the criterion values for equal distances.

CONCLUSIONS

This study offers an evidence base for selecting more interpretable patient-reported rating scale response categories. However, problems associated with raw rating scale data, primarily related to their ordinal structure also became apparent. This argues for the application of methodologies such as Rasch measurement. Rating scale response categories need to be treated with rigour in the construction and analysis of rating scales.