Psychometric characteristics of the Parkinson's disease questionnaire (PDQ-39)—Ecuadorian version

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 holistic approach to evaluating Parkinson's disease, using the Delphi method: a linear evaluation index

BACKGROUND

Parkinson's disease (PD) is a chronic disease that presents a multitude of symptoms, with symptoms of both motor and nonmotor nature. The Delphi method is widely used to create consensuses among experts in a field of knowledge.

OBJECTIVE

In order to reach a consensus on the values that should be assigned to the different motor and nonmotor manifestations of Parkinson's disease, a linear evaluation index (LEI) was created. Subsequently, the metric properties of this index were studied.

METHODS

120 consecutive patients with a Parkinson's diagnosis were chosen in accordance with the UKPDSBB criteria. The Delphi method was used to reach a consensus among experts regarding the values of each of the manifestations included. Subsequently, the following attributes were analyzed: quality and acceptability of the data; reliability, in terms of internal consistency, reliability index, Cronbach's alpha and standard error of measurement; and validity, in terms of convergent validity and validity for known groups.

RESULTS

Twenty-five experts participated. The importance factor did not differ between the first round and the second round (chi-square test). We analyzed the responses that assigned percentage values to the 10 dimensions of the LEI. Both in the first and in the second round, the values of the scattering coefficient Vr were always close to 0. The homogeneity index was 0.36; the corrected-item total correlation values ranged from 0.02 to 0.7; Cronbach's α was 0.69; and the SEM was 4.23 (55.1%).

CONCLUSIONS

The LEI was obtained through rigorous recommended methodology. The results showed adequate metric properties.

Tools to assess the quality of life in patients with Parkinson's disease: a systematic review

INTRODUCTION

The clinical, social, and economic implications of Parkinson's disease (PD) are significant; disability occurs leading to a low quality of life (QoL). Information on the QoL of patients with PD and studies on the relationship between QoL and motor and cognitive function are necessary for both research and clinical use to make informed decisions in healthcare and rehabilitation. The aim of this study was to determine which scales are most used to assess QoL in patients with PD.

AREA COVERED

A literature search was conducted in MEDLINE, Scopus, CINAHL, PsycINFO, and Web of Science. Two authors independently identified eligible studies based on predefined inclusion criteria and extracted the data. Study quality and the risk of bias were assessed using the COSMIN checklist.

EXPERT OPINION

116 suitable studies were included, and 42 different instruments were identified. The most frequently used scales were the 39-items and 8-items Parkinson's Disease Questionnaire (PDQ-39) (PDQ-8). These findings suggest further investigation of existing PD outcome measures would benefit patients, researchers, and clinicians. Validated, universal outcome measures are required to allow comparisons across practice; therefore, we recommend that future researchers use a common set of outcome assessments based on the results of this review.

Responsiveness of Objective vs. Clinical Balance Domain Outcomes for Exercise Intervention in Parkinson's Disease

Background: Balance deficits in people with Parkinson's disease (PD) are often not helped by pharmacological or surgical treatment. Although balance exercise intervention has been shown to improve clinical measures of balance, the efficacy of exercise on different, objective balance domains is still unknown.

Objective: To compare the sensitivity to change in objective and clinical measures of several different domains of balance and gait following an Agility Boot Camp with Cognitive Challenges (ABC-C) intervention.

Methods: In this cross-over, randomized design, 86 individuals with PD participated in 6-week (3×/week) ABC-C exercise classes and 6-week education classes, consisting of 3–6 individuals. Blinded examiners tested people in their practical off state. Objective outcome measures from wearable sensors quantified four domains of balance: sway in standing balance, anticipatory postural adjustments (APAs) during step initiation, postural responses to the push-and-release test, and a 2-min natural speed walk with and without a cognitive task. Clinical outcome measures included the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III, the Mini Balance Evaluation Systems Test (Mini-BESTest), the Activities of Balance Confidence (ABC), and the Parkinson's Disease Questionnaire (PDQ-39). The standardized response means (SRM) of the differences between before and after each intervention compared responsiveness of outcomes to intervention. A linear mixed model compared effects of exercise with the active control—education intervention.

Results: The most responsive outcome measures to exercise intervention with an SRM > 0.5 were objective measures of gait and APAs, specifically arm range of motion, gait speed during a dual-task walk, trunk coronal range of motion, foot strike angle, and first-step length at step initiation. The most responsive clinical outcome measure was the patient-reported PDQ-39 activities daily living subscore, but all clinical measures had SRMs <0.5.

Conclusions: The objective measures were more sensitive to change after exercise intervention compared to the clinical measures. Spatiotemporal parameters of gait, including gait speed with a dual task, and APAs were the most sensitive objective measures, and perceived functional independence was the most sensitive clinical measure to change after the ABC-C exercise intervention. Future exercise intervention to improve gait and balance in PD should include objective outcome measures.

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.

Cross-cultural validity, reliability, and psychometric properties of the persian version of the scales for outcomes in Parkinson's disease-psychosocial questionnaire

Objectives. Considering the influence of different motor and nonmotor features of Parkinson's disease (PD), it is important to evaluate the psychosocial functioning of the patients. For this purpose, the scales for outcomes in Parkinson's disease-psychosocial questionnaire (SCOPA-PS) has been previously designed. The aim of our study was to assess the cross-cultural validation and psychometric properties of the Persian version of the SCOPA-PS. Methods. One hundred and ten nondemented idiopathic Parkinson's disease (IPD) patients were consecutively recruited from an outpatient referral movement disorder clinic. Eligible patients filled up a number of questionnaires including the Persian version of SCOPA-PS during the face-to-face interview session and clinical examination to measure disease severity, nonmotor psychiatric symptoms, and health-related quality of life (HRQoL). Results. The highest and lowest correlation coefficients of internal consistency were reported for item 7 on "asking for help" (r = 0.765) and item 5 on "sexual problems" (r = 0.553). Cronbach's alpha reliability coefficient of the entire scale was 0.87 (95% CI: 0.83-0.90). The Hoehn and Yahr stage (r = 0.34, P < 0.001), Schwab and England ADL scale (r = -0.55, P < 0.001), anxiety (r = 0.64, P < 0.001), depression (r = 0.71, P < 0.001), and fatigue (r = 0.35, P < 0.001) were significantly correlated with the total score of the SCOPA-PS questionnaire. Conclusions. The Persian version of SCOPA-PS is a highly reliable and valid scale to measure psychosocial functioning in IPD patients with different sex, age-group, and educational level, which could be applied in future researches. Disease severity scales, depression, anxiety, fatigue, and different domains of HRQoL were all associated with psychosocial functioning in PD patients.

Health-related quality of life of australians with Parkinson disease: a comparison with international studies

PURPOSE

This study describes the health-related quality of life (HRQOL) of Australians living with Parkinson disease (PD) and compares the findings to international reports.

METHODS

The Parkinson's Disease Questionnaire-39 (PDQ-39) was used to measure HRQOL in 210 individuals with PD living in Australia. In parallel, a tailored literature search identified previous studies on HROQL in people with PD. A quantitative meta-analysis with a random-effects model was used to compare the HRQOL of individuals with PD living in Australia and other countries.

RESULTS

The mean PDQ-39 summary index (SI) score for this sample of Australians with PD was 20.9 (SD 12.7). Ratings for the dimension of social support and stigma were significantly lower than ratings for bodily discomfort, mobility, activities of daily living, cognition, and emotional well-being. Comparing the Australian and international PD samples revealed a significant heterogeneity in overall HRQOL (I(2)=97%). The mean PDQ-39 SI scores for Australians were lower, indicating better HRQOL relative to samples from other countries.

CONCLUSIONS

This Australian sample with PD perceived their HRQOL as poor, although it was less severely compromised than that of international samples. While further research is required, these findings can inform the clinical decision-making processes of physiotherapists.

Validation of an Estonian version of the Parkinson's Disease Questionnaire (PDQ-39)

Introduction

Diagnosis and management of Parkinson's disease (PD) rely heavily on evaluation of clinical symptoms and patients' subjective perception of their condition. The purpose of this study was to evaluate the validity, acceptability, and reliability of the Estonian version of the 39-question Parkinson 's disease Questionnaire (PDQ-39).

Methods

Study subjects were approached during their regular clinic follow-up visits. 104 patients consented to the study and 81 completed questionnaires were used for subsequent testing of psychometric characteristics, validity and reliability.

Results

The content validity was assessed through qualitative content analysis during the pilot study. The patients indicated that the questions were relevant to measure the quality of life of people with PD.

The analysis of means showed that the ceiling and floor effects of domain results were within the limits of 15% of Summary Index and of all domains except Stigma, Social Support and Communication where the ceiling effect was 16% to 24% of the responses. Convergent validity was interpreted through correlation between disease severity and PDQ-39 domains. There was a statistically significant difference between the domain scores in patients with mild versus moderate PD in domains of Mobility, ADL, and Communication but not for Stigma, Social Support and Cognition. The reliability was good, Cronbach alpha for all domains and summary index was over 0.8 and item-test correlations between domains and summary index ranged from 0.56 to 0.83.

Conclusion

The psychometric characteristics of an Estonian version of the PDQ-39 were satisfactory. The results of this study were comparable to the results of previous validation studies in other cultural settings in UK, USA, Canada, Spain and Italy.

The Estonian version of the PDQ-39 is an acceptable, valid and reliable instrument for quality of life measurement in PD patients.

Determinants of quality of life in Brazilian patients with Parkinson's disease

Our objective was to identify determinants of health-related quality of life (HRQoL) in a cohort of Brazilian patients with Parkinson's disease (PD). Patients were evaluated by means of the Hoehn and Yahr staging (H&Y), Unified Parkinson's Disease Rating Scale (UPDRS), Schwab and England scale (S&E), Mini-Mental State Exam, Geriatric Depression Scale, and Hospital Anxiety and Depression Scale (HADS). HRQol was assessed using the MOS-Short-Form 36 (SF-36), the Parkinson's disease Questionnaire (PDQ-39), and the Scales for Outcomes in Parkinson's Disease-Psychosocial Questionnaire (SCOPA-PS). 144 patients were evaluated (mean age 62 years; 53.5% men; mean duration of illness 6.6 years; median H&Y, 2 (range: 1-4). Mean SCOPA-PS and PDQ-39 Summary Index (SI) were 39.2 and 40.7, respectively. Both, PDQ-39 and SCOPA-PS SIs correlated at a moderate level (r = 0.30-0.50) with H&Y, S&E, total UPDRS, HADS subscales, and SF-36 Physical and Mental Components. PDQ-39 and SCOPA-PS were closely associated (r = 0.73). HRQoL significantly deteriorated as H&Y progressed, as a whole. Mood disturbances, disability, motor complications, and education were independent predictors of HRQoL in the multivariate analysis model. In PD Brazilian patients, HRQoL correlated significantly with diverse measures of severity. Depression showed to be the most consistent determinant of HRQoL, followed by disability, motor complications, and education years. There was a close association between the PDQ-39 and SCOPA-PS summary scores.

Anxiety and depression: main determinants of health-related quality of life in Brazilian patients with Parkinson's disease

Determinants of health-related quality of life (HRQoL) were assessed in 115 Brazilian patients (56.5% males; mean age 62.5 years) with Parkinson's disease (PD). Hoehn and Yahr (H&Y) staging, Scales for Outcomes in Parkinson's Disease-Motor Scale (SCOPA-MS), Cumulative Illness Rating Scale-Geriatrics, Hospital Anxiety and Depression Scale (HADS), Parkinson's Disease Questionnaire (PDQ-39), and SCOPA-Psychosocial Questionnaire (SCOPA-PS) were applied. Median H&Y was 3 and the SCOPA-MS score was 25.6+/-13.1. The proportion of patients who scored > or =11 points in the HADS-Depression and HADS-Anxiety subscales were 47% and 30.4%, respectively. In the multivariate model, HADS-Anxiety or HADS-Depression (p<0.0001), disability (SCOPA-MS II) (p=0.0001) and comorbidity (p=0.0005) were independently associated to PDQ-39 and SCOPA-PS. Mood disturbances were the main determinants of HRQoL.

Two questionnaires for Parkinson’s disease: are the PDQ-39 and PDQL equivalent?

BACKGROUND

Although there is a wide range of specific health-related quality of life (HRQoL) measures for Parkinson's disease (PD), their psychometric attributes have never been compared.

OBJECTIVE

To compare the psychometric characteristics of the Parkinson's Disease Questionnaire-39 items (PDQ-39) and Parkinson's Disease Quality of Life Questionnaire (PDQL).

METHODS

The PDQ-39 and PDQL were simultaneously applied to 187 PD patients. Additional assessments included Hoehn and Yahr staging, Schwab and England Scale (SES), Unified Parkinson's Disease Rating Scale, Pfeiffer's Short Portable Mental Status Questionnaire (SPMSQ) and Hospital Anxiety and Depression Scale (HADS). Criteria for acceptability, scaling assumptions, reliability, construct validity and precision were drawn up.

RESULTS

Both the PDQ-39 and PDQL proved very similar in the following aspects: acceptability (no floor or ceiling effect); scaling assumptions (79.5% and 80% respectively of item-total correlations fitted the standard); internal consistency (PDQ-39 domains, alpha = 0.43-0.93; PDQL domains, alpha = 0.70-0.88); stability (intraclass correlation coefficient = 0.76-0.90); and internal validity (PDQ-39, r = 0.09-0.70; PDQL, r = 0.52-0.71). Convergent validity between the two questionnaires was moderate to high (r = -0.91 for summary indices). Precision was higher for the PDQ-39 Summary Index, and predictors were the same for both measures (mood disorders and disability).

CONCLUSIONS

Although the psychometric properties tested are quite similar in both measures, mainly insofar as summary indices are concerned, differences in some attributes and structural content should nevertheless be considered when comparing both instruments.

The suitability of patient‐based measures in the field of Parkinson's disease: A systematic review

The aim of this study is to appraise the suitability of current quality of life (QOL) questionnaires for use in the field of Parkinson's disease (PD). Computerized bibliographic databases were screened for publications from 1960 to December 2006. Predefined selection criteria were used to identify QOL questionnaires in PD studies. Two investigators independently assessed and, subsequently, agreed on a set of multidimensional generic and PD-specific QOL questionnaires. Data were extracted concerning the internal structure, reliability, validity, and responsiveness of the included questionnaires. Sixteen-questionnaires were found, of which 14 questionnaires were included (six generic measures and eight PD-specific). In general, the psychometrics of all the questionnaires were adequately described. Sensitivity to change, however, has been reported for only a limited number of instruments. Almost all included questionnaires used QOL as a keyword, but only two questionnaires fitted the broad QOL definition used in this review. Considering the few "real " QOL questionnaires, we conclude that there is a strong need for such instruments.

Testing the validity of the PDQ-39 in patients with MSA

We assessed the validity of the PDQ-39, a disease-specific health-related quality of life instrument for patients with Parkinson's disease, in patients with multiple system atrophy (MSA). Two hundred and seventy-nine patients completed the PDQ-39, the EQ-5D, the Hospital Anxiety and Depression Scale, and scales of life satisfaction and disease severity. Ceiling and floor effects were noted in some dimensions, and Mobility was skewed towards the severe end of the spectrum. Apart from the dimension of Social Support, all dimensions had high internal consistency. The factor structure of the PDQ-39 in MSA was stable, and convergent and divergent validity with other measures of quality of life and mental health were good. However, many of the specific features of MSA are not reflected in the PDQ-39. Higher order factor analysis did not support the use of a single summary index. We conclude that the PDQ-39 has only limited validity in patients with MSA.

Independent validation of SCOPA–psychosocial and metric properties of the PDQ-39 Brazilian version

The objective of this study was to perform an independent validation of the Scales for Outcomes in Parkinson's Disease-Psychosocial questionnaire (SCOPA-PS) and assessment of the Parkinson's Disease Questionnaire (PDQ-39), Brazilian version. Patients were evaluated by means of the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr staging (HY), Schwab and England scale, Mini-Mental State Examination, and Hospital Anxiety and Depression Scale. Health-related quality of life was evaluated using the MOS-Short Form 36 (SF-36), PDQ-39, and SCOPA-PS. One hundred forty-four patients were included (mean age, 62 years; 53.5% males; mean duration of illness, 6.6 years; HY, 1-4). Mean SCOPA-PS and PDQ-39 Summary Index (SI) were 39.2 and 40.7, respectively. The internal consistency of SCOPA-PS (Cronbach's alpha = 0.84; item-total correlation, 0.44-0.73) and PDQ-39 dimensions (alpha = 0.61-0.85; item-total correlation, 0.46-0.82) were satisfactory. Concerning the stability of the questionnaires, intraclass correlation coefficient (ICC) values were 0.71 for the SCOPA-PS and 0.86 for the PDQ-39 SI. ICC for PDQ-39 dimensions ranged from 0.52 (social support) to 0.80 (stigma). Standard error of measurement (SEM) values for each PDQ-39 dimension ranged from 0.49 (emotional well-being) to 17.52 (social support). SEM values for SCOPA-PS and PDQ-39 SI were 11.84 and 6.72, respectively. A significant correlation of SCOPA-PS and PDQ-39 SI with the SF-36 physical (-0.42 and -0.52, respectively) and mental components (-0.41) was found. Correlation between SCOPA-PS and PDQ-39 SI was 0.73 (all coefficients, P < 0.0001). The SCOPA-PS and PDQ-39, Brazilian versions, have satisfactory metric attributes.

Cross-cultural evaluation of the short form 8-item Parkinson's Disease Questionnaire (PDQ-8): results from America, Canada, Japan, Italy and Spain

OBJECTIVE

The purpose of this study was to evaluate the psychometric properties of a short form health survey, the Parkinson's Disease Questionnaire (PDQ-8), cross-culturally, by comparing results gained from this instrument to the original longer form instrument-the PDQ-39.

DESIGN

Data are from the Global Parkinson's Disease Survey.

OUTCOMES

The 8-item Parkinson's Disease Questionnaire Single Index Score (PDQ-8-SI). In this study, we evaluate response rate, scaling assumptions, and data quality, in terms of comparability of results with the parent form from which the PDQ-8 was derived, of the instrument in the USA, Canada, Spain, Italy and Japan.

RESULTS

The PDQ-8 was found to produce results that were very similar to the parent form across all five countries. However, it should be borne in mind that the PDQ-8 was nested within the PDQ-39, and results may be influenced by this.

CONCLUSIONS

Results suggest that the PDQ-8 is a valid and reliable measure that can be appropriately and meaningfully used in cross-cultural studies.