Progression of Parkinson's disease as evaluated by Hoehn and Yahr stage transition times.

This study was carried out to evaluate progression in Parkinson's disease (PD) by analyzing time taken to transit from one Hoehn and Yahr (H&Y) stage to the next stage and to investigate the variables that would be associated with H&Y transition times using a large PD database that contained prospectively collected information. Data were obtained from the movement disorder database of the National Neuroscience Institute in Singapore. Kaplan-Meier (KM) survival analysis was adopted to investigate the time taken to progress through various H&Y stages. Cox regression analysis was used to examine the association between the baseline variables at the entry point of each H&Y stage and the progression to the next stage. A total of 695 patients (mean age: 65.2, male: 57.3%) were studied. Using KM analysis, the median time taken to transit from H&Y stage 1 to 2, 2 to 2.5, 2.5 to 3 were 20, 62, and 25 months, respectively; whereas the median time taken to progress from stage 3 to 4 and 4 to 5 were 24 and 26 months, respectively. Cox regression analysis revealed that older age-at-diagnosis, longer PD duration, and higher Unified Parkinson's Disease Rating Scale (UPDRS) motor scores at baseline were associated with a significantly faster progression through various H&Y stages. Gender and ethnicity were not associated with disease progression. In conclusion, H&Y transition time is a useful measure of disease progression in PD and may be utilized in clinical studies evaluating therapeutic interventions and prognostic factors in PD.

Responsiveness of the EQ-5D and 8-item Parkinson's Disease Questionnaire (PDQ-8) in a 4-year follow-up study.

OBJECTIVE: The purpose of this study was to evaluate the responsiveness of the EQ-5D and the Parkinson's Disease Questionnaire (PDQ-8) to deterioration in health-related quality of life (HRQoL) in patients with Parkinson's disease (PD). METHODS: HRQoL and clinical data collected from 31 patients with PD (male: 74.2%, mean age: 61 years) who were surveyed with the EQ-5D and the PDQ-8 questionnaires in 2002 and 2006/2007 were analyzed. Responsiveness of the EQ-5D, PDQ-8, and Hoehn and Yahr (H&Y) staging were assessed according to Cohen's effect size (ES) and standardized response mean (SRM). RESULTS: The mean (standard deviation) EQ-5D index and PDQ-8 summary index (PDQ-8SI) scores were 0.76 (0.23) and 17.7 (14.2) at baseline and 0.52 (0.33) and 35.1 (17.4) at year four. Based on both ES and SRM indices, the rank order of responsiveness of the studied measures, from high to low, was PDQ-8SI (ES = 1.22), EQ-5D index score (ES = 1.06), H&Y score (ES = 0.82), and the EQ-VAS score (ES = 0.24). CONCLUSION: Both the EQ-5D and PDQ-8 are responsive to changes in health burden of the Parkinson's disease over a 4-year period.

Cognitive decline in early Parkinson's disease.

Data on the prevalence and severity of cognitive impairment among patients with newly diagnosed idiopathic Parkinson's disease (PD) is limited. Using a prospectively collected clinical database, we studied the longitudinal trend of mini-mental state examination (MMSE) change and baseline factors predictive for MMSE decline. One hundred six patients with mean age of 61.2 years and mean baseline MMSE of 27.8 +/- 2.3 were studied. MMSE increased by 0.4 points/year among patients without cognitive decline (n = 73) and decreased by 2.39 points/year among patients with cognitive decline (n = 33). Univariate analysis demonstrated education, age of diagnosis, depression, and diabetes mellitus to be associated with cognitive decline. Motor scores and hallucination were not associated with cognitive decline. Multivariate analysis demonstrated higher level of education to be protective (HR = 0.91, 95% CI 0.82-0.99, P = 0.047) and depression having borderline significance in predicting cognitive decline (HR = 2.00, 95% CI 0.97-4.15, P = 0.061). We found that 31% of newly diagnosed idiopathic PD patients have measurable cognitive decline at an early stage of disease. Higher education is protective while depression may be predictive of cognitive decline.

Determination of the longitudinal validity and minimally important difference of the 8-item Parkinson's Disease Questionnaire (PDQ-8).

The aim of our study was to assess the longitudinal validity of the 8-item Parkinson's Disease Questionnaire (PDQ-8) in terms of responsiveness and test-retest reliability and to determine the minimally important difference (MID) for PDQ-8 using the anchor-based approach in Asians with Parkinson's disease (PD). A consecutive sample of PD patients attending a tertiary neuroscience clinic in Singapore completed the English or Chinese version of PDQ-8 twice during two different clinic visits. During the second visit, patients were also asked to rate their changes in health in general, PD severity, and overall impact of PD since at the time of their first visit 1 year ago using a 5-point response scale. A total of 96 patients participated in the study. For patients who reported changed conditions in the second visit, responsiveness measured by Cohen's effect size, standardized response mean, and Guyatt's responsiveness index ranged from 0.21 to 0.68. The intraclass correlation coefficient values calculated using patients reporting no change in health or PD status ranged from 0.64 to 0.76. The mean changed PDQ-8 summary index score in patients who reported that their health or PD status worsened only "a little bit" ranged from 5.8 to 7.4 points. Our current results show that PDQ-8 is a longitudinally reliable and responsive measure for assessing the health-related quality of life in patients with PD. The MID of the PDQ-8 estimated in the study will further support the use of this instrument in both clinical research and practice.

Validation of PDQ-8 as an independent instrument in English and Chinese.

Previous validation studies on the PDQ-8, a brief disease-specific quality of life instrument, were performed with the PDQ-8 nested in the original PDQ-39. Such an approach may influence patient responses and the psychometric properties of the PDQ-8. We therefore undertook this study to validate the PDQ-8 when administered independently in English and Chinese and found good item-to-scale correlations (correlation coefficient: 0.44-0.68) and internal consistency (Cronbach's alpha: 0.81, 0.87). Factor analyses yielded a component on which all 8 questions were substantially loaded (loading range: 0.55-0.77). Scree plots also showed the one-factor solution thereby validating the PDQ-8 summary index. Construct validation against the Hoehn and Yahr stage and UPDRS motor scores showed significant correlations between higher PDQ-8 summary index and increased disease severity in both English and Chinese versions. Our results show the PDQ-8 to be a valid and reliable disease-specific HRQoL instrument for PD when used independently of the PDQ-39.

Spectrum and burden of movement disorder conditions in a tertiary movement disorders centre--a 10-year trend.

INTRODUCTION: The precise burden of movement disorder conditions in our movement disorders centre is unclear. This study investigated the clinical burden of the Movement Disorders Clinic (MDC) in National Neuroscience Institute (NNI) over 10 years, aiming to identify the burden and spectrum of movement disorders conditions, to facilitate future resource allocation. MATERIALS AND METHODS: We identified all patient visits from January 2002 to December 2011 at MDC from the Movement Disorders (MD) database using a standardised data collection form. RESULTS: There was a linear increase in the clinical burden of MDC during this period. Parkinsonism comprised 71.6% of this clinical burden of which 84.8% were Parkinson's disease (PD) patients. Dividing the incident cases of MD conditions into two 5 years' blocks, the proportion of PD cases had not changed. There was significant increase in time to diagnosis for PD, hemifacial spasm and dystonia. CONCLUSION: There was nearly 4-fold increase in the burden of movement disorders conditions in our tertiary condition within a decade. However, we did not find increasing proportion of PD cases which would be in line with an ageing population. This could be due to the fact that we are still in the early stages of an ageing population and we postulate that this proportion will go up in the future. The increased time to diagnosis may indicate increasing waiting time to see a movement disorders specialist and that current outreach effort to promote awareness may not be reaching its target audience. The upward trend of clinical burden indicates a need for increased resource allocation to cope with demand for movement disorders services.

Is EQ-5D a valid quality of life instrument in patients with Parkinson's disease? A study in Singapore.

INTRODUCTION: The purpose of the present study was to evaluate the validity of the EQ-5D in patients with Parkinson's disease (PD) in Singapore. MATERIALS AND METHODS: In a cross-sectional survey, patients with PD completed English or Chinese version of the EQ-5D, the 8-item Parkinson's disease questionnaire (PDQ-8), and questions assessing socio-demographic and health characteristics. Clinical data were retrieved from patients' medical records. The validity of the EQ-5D was assessed by testing a-priori hypotheses relating the EQ-5D to the PDQ-8 and clinical data. RESULTS: Two hundred and eight PD patients (English speaking: 135) participated in the study. Spearman correlation coefficients between the EQ-5D and PDQ-8 ranged from 0.25 to 0.75 for English-speaking patients and from 0.16 to 0.67 for Chinese-speaking patients. By and large, the EQ-5D scores were weakly or moderately correlated with Hoehn and Yahr stage (correlation coefficients: 0.05 to 0.43), Schwab and England Activities of Daily Living score (correlation coefficients: 0.10 to 0.60), and duration of PD (correlation coefficients: 0.16 to 0.43). The EQ-5D index scores for patients with dyskinesia or "wearing off" periods were significantly lower than those without these problems. The EQ-5D Visual Analog Scale (EQ-VAS) scores also differed for English-speaking patients with deferring dyskinesia, "wearing off" periods, or health transition status; however, such differences were not observed in patients who completed the survey in Chinese. CONCLUSIONS: The EQ-5D questionnaire appears valid for measuring quality of life in patients with PD in Singapore. However, the validity of EQ-VAS in Chinese-speaking patients with PD should be further assessed.

Use of complementary therapies in patients with Parkinson's disease in Singapore.

To determine the frequency and spectrum of complementary therapy (CT) use and its association with sociodemographic or disease-specific characteristics among Asian patients with Parkinson's disease (PD) in Singapore, we interviewed 159 patients using a structured questionnaire. Sixty-one percent (95% CI=55-67) of participants used at least one type of CT for PD, of which the most common were traditional medicine, acupuncture, and vitamins/health supplements. Among CT users, 40% (95% CI=32-48) subjectively reported some improvement of their symptoms. However, only 16% informed their physicians of their use of CT. Due to unequal follow-up times, a survival analysis approach was adopted for statistical analysis. The rate of starting CT use was 1.2/100 person months. At 3 years after PD diagnosis, 48% had started using CT. Among a subgroup of participants, those with a baseline Unified Parkinson's Disease Rating Scale motor score of more than 16 were 2.5 times more likely to use CT compared to those with a baseline score of 16 or less (P=0.031; 95% CI=1.1-5.8). CT use was not associated with age of onset of PD or other sociodemographic factors. The use of CT is high among Asian PD patients. Patients with more severe motor dysfunction at onset are more likely to use CT.