Reliability and validity of PDQ-39: a quality-of-life measure for patients with PD in China

Psychometric properties of the Parkinson's disease Questionnaire-39 and its short form Parkinson's disease Questionnaire-8: A systematic review and meta-analysis

Parkinson's disease (PD) affects Quality of Life (QoL), since it is responsible for cognitive impairment, non-motor, and motor symptoms. Outcome measures are fundamental for evaluating treatment's effect on QoL over time. This systematic review aimed to identify the psychometric properties of PDQ-39 and PDQ-8 in the different populations in which they were validated. The electronic databases systematically searched are MEDLINE (via PubMed), CINAHL, SCOPUS, and Web of Science; the research was conducted in July 2023. The psychometric properties considered were those of the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist. Risk of bias was assessed using the COSMIN checklist. The search identified 1306 articles. 398 duplicates were eliminated; 908 articles were analyzed reading title and abstract; 799 were finally excluded because used PDQ-39 and PDQ-8 as outcome measures or were not dealing with psychometric properties; 66 articles were excluded after reading the full text. 43 articles were included in the review; meta-analysis showed all the Cronbach's alpha values were statistically significant for all the subscales of PDQ-39 and PDQ-8. PDQ-39 demonstrated to be a specific HRQoL questionnaire that is correlated with generic HRQoL questionnaires, in fact in many studies included in the review, correlations with SF-36 were found. In the last studies about psychometric properties of PDQ-8 emerged that it is a practical and informative instrument that can be easily used in clinical settings, especially in busy ones, but also in large-scale studies in which a brief instrument would be preferred.

A summary index derived from Kinect to evaluate postural abnormalities severity in Parkinson’s Disease patients

Postural abnormalities are common disabling motor complications affecting patients with Parkinson’s disease (PD). We proposed a summary index for postural abnormalities (IPA) based on Kinect depth camera and explored the clinical value of this indicator. Seventy individuals with PD and thirty age-matched healthy controls (HCs) were enrolled. All participants were tested using a Kinect-based system with IPA automatically obtained by algorithms. Significant correlations were detected between IPA and the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) total score (rs = 0.369, p = 0.002), MDS-UPDRS-III total score (rs = 0.431, p < 0.001), MDS-UPDRS-III 3.13 score (rs = 0.573, p < 0.001), MDS-UPDRS-III-bradykinesia score (rs = 0.311, p = 0.010), the 39-item Parkinson’s Disease Questionnaire (PDQ-39) (rs = 0.272, p = 0.0027) and the Berg Balance Scale (BBS) score (rs = −0.350, p = 0.006). The optimal cut-off value of IPA for distinguishing PD from HCs was 12.96 with a sensitivity of 97.14%, specificity of 100.00%, area under the curve (AUC) of 0.999 (0.997–1.002, p < 0.001), and adjusted AUC of 0.998 (0.993–1.000, p < 0.001). The optimal cut-off value of IPA for distinguishing between PD with and without postural abnormalities was 20.14 with a sensitivity, specificity, AUC and adjusted AUC of 77.78%, 73.53%, 0.817 (0.720–0.914, p < 0.001), and 0.783 (0.631–0.900, p < 0.001), respectively. IPA was significantly correlated to the clinical manifestations of PD patients, and could reflect the global severity of postural abnormalities in PD with important value in distinguishing PD from HCs and distinguishing PD with postural abnormalities from those without.

Quality of life in Parkinson's disease: Italian validation of the Parkinson's Disease Questionnaire (PDQ-39-IT)

Translation and cross-cultural adaptation of the 39-item Parkinson's Disease Questionnaire (PDQ-39) to the Italian culture was performed by Oxford University Innovation in 2008, but this version has never been validated. Therefore, we performed the process of validation of the Italian version of the PDQ-39 (PDQ-39-IT) following the "Consensus-Based Standards for the Selection of Health Status Measurement Instruments" checklist. The translated PDQ-39-IT was tested with 104 patients diagnosed with Parkinson's disease (PD) who were recruited between June and October 2017. The mean age of the participants was 65.7 ± 10.2 years, and the mean duration of symptoms was 7.4 ± 5.3 years. The internal consistency of the PDQ-39-IT was assessed by Cronbach's alpha and ranged from 0.69 to 0.92. In an assessment of test-retest reliability in 35 of the 104 patients, the infraclass correlation coefficient (ICC) ranged from 0.85 to 0.96 for the various subitems of the PDQ-39-IT (all p < 0.01). Spearman's rank correlation coefficient for the validity of the PDQ-39-IT and the Italian version of the 36-Item Short Form (SF-36) was - 0.50 (p < 0.01). The results show that the PDQ-39-IT is a reliable and valid tool to assess the impact of PD on functioning and well-being. Thus, the PDQ-39-IT can be used in clinical and research practice to assess this construct and to evaluate the overall effect of different treatments in Italian PD patients.

Sex Differences in the Clinical Progression of Parkinson's Disease

OBJECTIVE

To describe characteristics of Parkinson's disease by sex and determine if differences in disease progression exist.

DESIGN

Longitudinal, observational study.

SETTING

Twenty-one National Parkinson Foundation Centers of Excellence.

PARTICIPANTS

People (N = 4,679; 63% men and 37% women) with idiopathic Parkinson's disease.

METHODS

Demographic and clinical data at enrollment and after 1 year were collected. We defined progression as a 1-year change in the following functional health outcome measures: (a) health-related quality of life (Parkinson's Disease Questionnaire-39), (b) Timed Up and Go test, (c) cognitive function, and (d) number of medications. We compared baseline characteristics between men and women. Then, linear regression models were built to assess the independent contribution of sex to progression.

RESULTS

At baseline, women were significantly more likely to be older and have greater disease severity and more comorbidities than men despite similar duration of disease. This finding corresponded to worse function as assessed by the Parkinson's Disease Questionnaire-39 and Timed Up and Go test but not to number of medications and cognitive function. After 1 year, declines across all functional measures except delayed recall occurred. No significant changes in Parkinson's Disease Questionnaire-39, Timed Up and Go, number of medications, or verbal fluency between men and women occurred. Women had a more significant improvement in delayed recall than men.

CONCLUSION

Numerous small baseline differences occurred between men and women with PD, although differences in markers of progression were few. Findings suggest that clinical manifestations and prognosis appear similar by sex under the same treatment conditions.

The effects of motor rehabilitation training on clinical symptoms and serum BDNF levels in Parkinson’s disease subjects

Increasing evidence suggests that motor rehabilitation may delay Parkinson’s disease (PD) progression. Moreover, parallel treatments in animals up-regulate brain-derived neurotrophic factor (BDNF). Thus, we investigated the effect of a motor rehabilitation protocol on PD symptoms and BDNF serum levels. Motor rehabilitation training consisted of a cycle of 20 days/month of physiotherapy divided in 3 daily sessions. Clinical data were collected at the beginning, at the end, and at 90 days follow-up. BDNF serum levels were detected by ELISA at 0, 7, 14, 21, 30, and 90 days. The follow-up period had a duration of 60 days (T30–T90). The results showed that at the end of the treatment (day 30), an improvement in extrapyramidal signs (UPDRS III; UPDRS III – Gait and Balance items), motor (6 Minute Walking Test), and daily living activities (UPDRS II; PDQ-39) was observed. BDNF levels were increased at day 7 as compared with baseline. After that, no changes in BDNF were observed during the treatment and in the successive follow-up. This study demonstrates that motor rehabilitation training is able to ameliorate PD symptoms and to increase temporarily BDNF serum levels. The latter effect may potentially contribute to the therapeutic action.

Virtual Reality-Based Training to Improve Obstacle-Crossing Performance and Dynamic Balance in Patients With Parkinson's Disease

BACKGROUND

Obstacle crossing is a balance-challenging task and can cause falls in people with Parkinson's disease (PD). However, programs for people with PD that effectively target obstacle crossing and dynamic balance have not been established.

OBJECTIVE

To examine the effects of virtual reality-based exercise on obstacle crossing performance and dynamic balance in participants with PD.

METHODS

Thirty-six participants with a diagnosis of PD (Hoehn and Yahr score ranging 1 to 3) were randomly assigned to one of three groups. In the exercise groups, participants received virtual reality-based Wii Fit exercise (VRWii group) or traditional exercise (TE group) for 45 minutes, followed by 15 minutes of treadmill training in each session for a total of 12 sessions over 6 weeks. Participants in the control group received no structured exercise program. Primary outcomes included obstacle crossing performance (crossing velocity, stride length, and vertical toe obstacle clearance) and dynamic balance (maximal excursion, movement velocity, and directional control measured by the limits-of-stability test). Secondary outcomes included sensory organization test (SOT), Parkinson's Disease Questionnaire (PDQ39), fall efficacy scale (FES-I), and timed up and go test (TUG). All outcomes were assessed at baseline, after training, and at 1-month follow-up.

RESULTS

The VRWii group showed greater improvement in obstacle crossing velocity, crossing stride length, dynamic balance, SOT, TUG, FES-I, and PDQ39 than the control group. VRWii training also resulted in greater improvement in movement velocity of limits-of-stability test than TE training.

CONCLUSIONS

VRWii training significantly improved obstacle crossing performance and dynamic balance, supporting implementation of VRWii training in participants with PD.

Psychometric study of the Persian short-form eight-item Parkinson's disease questionnaire (PDQ-8) to evaluate health related quality of life (HRQoL)

Background

To assess validation and reliability of the Persian version of the short-form 8-item Parkinson’s disease questionnaire (PDQ-8) and to compare its psychometric properties with that of the long-form questionnaire (PDQ-39) in order to evaluate the health-related quality of life (HRQoL) in patients with Parkinson’s disease (PD).

Methods

This cross-sectional study was conducted on 114 non-demented idiopathic PD (IPD) patients consecutively recruited from an outpatient referral movement disorder clinic. Patients were interviewed to fill in the Persian version of PDQ-39 and PDQ-8 questionnaires and clinical examination was performed to measure disease severity indices.

Results

The Cronbach’s alpha coefficient of the entire PDQ-8 was 0.740 (95% CI: 0.661-0.806). Replacement of PDQ-8 items with other questions with the highest internal consistency within each dimension of the original PDQ-39 did not improve Cronbach’s alpha coefficient [0.723 (95% CI: 0.639-0.794)]. The scores from both PDQ-8 and PDQ-39 had significant correlation with the Hoehn & Yahr (r_PDQ-8 = 0.376, r_PDQ-39 = 0.442), and Schwab & England (r_PDQ-8 = -0.503, r_PDQ-39 = -0.598) disease severity scales and disease duration (r_PDQ-8 = 0.342, r_PDQ-39 = 0.396).

Conclusions

Persian version of the short-form PDQ (PDQ-8) was shown to be a valid and reliable instrument to assess disease-specific HRQoL in a PD population when used independently. Although the PDQ-8 items were not necessarily those with the highest internal consistency in the components of PDQ-39, they entirely showed proper psychometric properties especially in mental and behavioral aspects. PDQ-8 is a practical and informative instrument in daily clinical practice where clinicians are in shortage of time and when a validated self-reported brief questionnaire is of value.

Factors influencing obstacle crossing performance in patients with Parkinson's disease

BACKGROUND

Tripping over obstacles is the major cause of falls in community-dwelling patients with Parkinson's disease (PD). Understanding the factors associated with the obstacle crossing behavior may help to develop possible training programs for crossing performance. This study aimed to identify the relationships and important factors determining obstacle crossing performance in patients with PD.

METHODS

Forty-two idiopathic patients with PD (Hoehn and Yahr stages I to III) participated in this study. Obstacle crossing performance was recorded by the Liberty system, a three-dimensional motion capture device. Maximal isometric strength of the lower extremity was measured by a handheld dynamometer. Dynamic balance and sensory integration ability were assessed using the Balance Master system. Movement velocity (MV), maximal excursion (ME), and directional control (DC) were obtained during the limits of stability test to quantify dynamic balance. The sum of sensory organization test (SOT) scores was used to quantify sensory organization ability.

RESULTS

Both crossing stride length and stride velocity correlated significantly with lower extremity muscle strength, dynamic balance control (forward and sideward), and sum of SOT scores. From the regression model, forward DC and ankle dorsiflexor strength were identified as two major determinants for crossing performance (R(2) = .37 to.41 for the crossing stride length, R(2) = .43 to.44 for the crossing stride velocity).

CONCLUSIONS

Lower extremity muscle strength, dynamic balance control and sensory integration ability significantly influence obstacle crossing performance. We suggest an emphasis on muscle strengthening exercises (especially ankle dorsiflexors), balance training (especially forward DC), and sensory integration training to improve obstacle crossing performance in patients with PD.