Mapping the EQ-5D index by UPDRS and PDQ-8 in patients with Parkinson's disease

A person-centered approach to characterizing longitudinal ambulatory impairment in Parkinson's disease

Loss of ambulation is common and highly variable in Parkinson's disease (PD), and poorly understood from the perspectives of those with PD. Gaining insights to the anticipated perceived trajectories and their drivers, will facilitate patient-centered care. Latent class growth analysis, a person-centered mixture modelling approach, was applied to 16,863 people with PD stratified by early (N = 8612; < 3 years), mid (N = 6181; 3-10 years) and later (N = 2070; > 10 years) disease to discern clusters with similar longitudinal patterns of self-reported walking difficulty, measured by EuroQoL 5D-5L that is validated for use in PD. There were four clusters in early and mid-disease strata, with a fifth identified in later disease. Trajectories ranged from none to moderate walking difficulty, with small clusters with severe problems. The percentage of subjects with moderate (early = 17.5%, mid = 26.4%, later = 32.5%) and severe (early = 3.8%, mid = 7.4%, later = 15.4%) walking difficulty at baseline increased across disease duration groups. The trajectories tended to be stable with variability in moderate and severe groups. Across strata, clusters with moderate to severe problems were associated with more severe impairment, depression, anxiety, arthritis, higher BMI, lower income, and lower education, but no consistent race or gender differences. The findings reveal distinct longitudinal patterns in perceived difficulties in walking in PD.

Feasibility and effectiveness of a remote individual rehabilitation program for people with Parkinson's disease living in the Brazilian Amazon: a randomized clinical trial

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder, and the current treatment involves pharmacological intervention and physiotherapy. Telerehabilitation, which involves remote support and guidance for patients undergoing rehabilitation, can potentially improve access to physiotherapy services for people with Parkinson's disease, especially those who face geographic barriers to healthcare. The primary aim of this study was to assess the feasibility and efficacy of a telerehabilitation program for people with Parkinson's disease living in an underrepresented community of the Brazilian Amazon. We conducted a parallel-group, single-center, single-blind, phase 2 randomized controlled clinical trial involving 19 participants diagnosed with Parkinson's disease from Belém, Brazil. Participants were assigned to a 4-week individual telerehabilitation program or a booklet-based exercise program (control group). Assessments were conducted before the intervention, immediately after the intervention, and 4 weeks after the end of the intervention. We showed that our telerehabilitation program had high adherence among patients, with minimal adverse effects. Both telerehabilitation and booklet orientation reduced the time to complete the Timed Up and Go test. In conclusion, our telerehabilitation program was feasible and effective for people with Parkinson's disease in an Amazonian setting. This trial was registered at the Registro Brasileiro de Ensaios Clínicos (ReBEC) under the identifier: RBR-6sz837s.

Evaluation and validation of a patient-reported quality-of-life questionnaire for Parkinson's disease

Background

Parkinson’s disease (PD) is a chronic, progressive illness with a profound impact on the health-related quality of life (HRQoL). Disease-specific patient-reported HRQoL measures, such as PDQ-39 and its short version PDQ-8, are increasingly used in clinical practice to address the consequences of PD on everyday life. Due to limitations in the content, especially in non-motor symptoms and sleep disturbances of PDQ-8, PDQoL7, a 7-item, short-term, self-reported, PD-specific HRQoL questionnaire was developed.

Methods

A representative sample of 60 adults with idiopathic PD completed the PDQoL7 questionnaire and the existing validated PDQ-8 and EQ-5D-5L questionnaires (all in Greek).

Results

PDQoL7 summary index strongly correlated with PDQ-8 (r_s = 0.833, P < 0.001) and EQ-5D-5L (r_s =  − 0.852, P < 0.001). The correlation between PDQoL7 and EQ-5D-5L was statistically significantly stronger compared to PDQ-8 and EQ-5D-5L (r_s =  − 0.852 vs rs =  − 0.789 respectively, P < 0.001). The internal consistency of PDQoL7 was not affected by item deletion (positive item to total correlations: 0.29–0.63). No redundant items (with inter-item correlation coefficients greater than 0.80) were identified. Cronbach’s α for PDQoL7 was comparable to PDQ-8 (0.804 versus 0.799 respectively). As PDQoL7 had three-dimensional structure, omega coefficient analysis confirmed its reliability (omega total: 0.88; omega hierarchical: 0.58).

Conclusions

PDQoL7 is an acceptable, easy to use, valid and reliable tool for the determination of HRQoL in PD patients that is potentially more comprehensive than PDQ-8 based on the available evidence. PDQoL7 could allow for a more thorough evaluation of the impact of PD and contribute to guiding healthcare decisions. This will be confirmed in subsequent analysis on larger patient cohorts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41687-022-00427-0.

Cost-effectiveness analysis of the Parkinson's KinetiGraph and clinical assessment in the management of Parkinson's disease

AIMS

The Parkinson's KinetiGraph (PKG) is a wrist-worn movement recording system that collates continuous, objective, data during daily activities in people with Parkinson's disease (PD) providing a report for clinicians. This study explores the cost-effectiveness of adding the PKG to routine PD assessments.

METHODS

A de novo Markov model of three health states: uncontrolled, controlled and death compared PKG plus routine assessment by a Movement Disease Specialist (MDS) versus routine assessment. Uncontrolled and controlled states were based on the Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) II and III scores. The transition between health states was dependent on improvement in MDS-UPDRS II and III, and transition to death state on all cause-mortality and PD-specific relative mortality risk. Markov cycle length was yearly beyond year 1 and lifetime horizon 22 years.

LIMITATIONS

PKG evidence incorporated in this analysis is based on findings from one clinical trial. Health state utilities were mapped and the probability of patients progressing from uncontrolled to controlled health state at the second visit and beyond was derived from a bootstrap method which assumed a normal distribution for MDS-UPDRS.

RESULTS

The addition of the PKG to usual PD assessments is a cost-effective intervention. PKG plus routine assessment is associated with lower total costs compared to routine assessment (£141,950 versus £159,312) and improved quality-adjusted life years (7.88 versus 7.61), resulting in an incremental cost-effectiveness ratio of -£64,978.99 and a net monetary benefit of £22,706.37 using a £20,000 threshold. Results were robust across sensitivity and scenario analyses.

CONCLUSIONS

Management of PD involves monitoring and evaluation of symptoms to assess disease progression and ensure appropriate treatment choices. Adding the PKG to clinical assessment in routine care allows for improved and objective identification of PD motor symptoms which can be used in clinical decision making to improve patient outcomes.

Parkinson's disease with early motor complications: predicting EQ-5D- 3L utilities from PDQ-39 data in the EARLYSTIM trial

Background

A utility value is a health-related quality of life metric (HRQoL) metric used in a cost-effectiveness analysis. While utilities as outcomes in the treatment of advanced Parkinson’s disease (PD) with deep brain stimulation (DBS) are available, they do not currently exist for PD with early motor complications. The objectives of this study were to predict utilities from observed disease-specific HRQoL data using two mapping algorithms, and investigate their performance in terms of longitudinal changes within and between treatment groups, and distribution by PD severity.

Methods

This is a post hoc analysis of data from the EARLYSTIM trial of DBS compared with best medical therapy (BMT) in PD patients with early motor complications We used two published algorithms comprising ordinal and multinomial regression models to map EQ-5D-3L utilities from observed PD-specific 39 item Questionnaire (PDQ-39) scores in EARLYSTIM. Utilities were calculated using the predicted functioning levels of EQ-5D-3L dimensions and the established EQ-5D-3L UK tariffs. Statistical analyses (analysis of variance, two-tailed Student’s t-test) were used to test the change from baseline within groups and difference in change from baseline between groups in utilities. Boxplots were developed to investigate the distribution of predicted utilities by PD severity, measured using the Hoehn and Yahr scale.

Results

The change from baseline in predicted mean utilities was statistically significant at all visits up to 24 months for the DBS group (p < 0.001) with both algorithms, and statistically significant at 12 months only (p = 0.04) for the BMT group with one algorithm. With both algorithms, the between-groups difference in change from baseline in predicted mean utilities favored DBS at all follow-up visits (p < 0.001). Based on the Hoehn and Yahr scale, predicted utilities deteriorated with increasing disease severity.

Conclusions

Among PD patients with early motor complications, utilities predicted by both mapping algorithms using PDQ-39 data demonstrated a statistically and clinically meaningful improvement with DBS compared with BMT. It was not possible to conclude if one algorithm was more responsive than other. In the absence of utilities collected directly from patients, mapping is an acceptable option permitting economic evaluations to be undertaken.

An Updated Systematic Review of Studies Mapping (or Cross-Walking) Measures of Health-Related Quality of Life to Generic Preference-Based Measures to Generate Utility Values

BACKGROUND

Mapping is an increasingly common method used to predict instrument-specific preference-based health-state utility values (HSUVs) from data obtained from another health-related quality of life (HRQoL) measure. There have been several methodological developments in this area since a previous review up to 2007.

OBJECTIVE

To provide an updated review of all mapping studies that map from HRQoL measures to target generic preference-based measures (EQ-5D measures, SF-6D, HUI measures, QWB, AQoL measures, 15D/16D/17D, CHU-9D) published from January 2007 to October 2018.

DATA SOURCES

A systematic review of English language articles using a variety of approaches: searching electronic and utilities databases, citation searching, targeted journal and website searches.

STUDY SELECTION

Full papers of studies that mapped from one health measure to a target preference-based measure using formal statistical regression techniques.

DATA EXTRACTION

Undertaken by four authors using predefined data fields including measures, data used, econometric models and assessment of predictive ability.

RESULTS

There were 180 papers with 233 mapping functions in total. Mapping functions were generated to obtain EQ-5D-3L/EQ-5D-5L-EQ-5D-Y (n = 147), SF-6D (n = 45), AQoL-4D/AQoL-8D (n = 12), HUI2/HUI3 (n = 13), 15D (n = 8) CHU-9D (n = 4) and QWB-SA (n = 4) HSUVs. A large number of different regression methods were used with ordinary least squares (OLS) still being the most common approach (used ≥ 75% times within each preference-based measure). The majority of studies assessed the predictive ability of the mapping functions using mean absolute or root mean squared errors (n = 192, 82%), but this was lower when considering errors across different categories of severity (n = 92, 39%) and plots of predictions (n = 120, 52%).

CONCLUSIONS

The last 10 years has seen a substantial increase in the number of mapping studies and some evidence of advancement in methods with consideration of models beyond OLS and greater reporting of predictive ability of mapping functions.

Mapping ALSFRS-R and ALSUI to EQ-5D in Patients with Motor Neuron Disease

BACKGROUND

The Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) is the preferred measure of health outcome in clinical trials in motor neuron disease (MND). It, however, does not provide a preference-based health utility score required for estimating quality-adjusted life-years in economic evaluations for health technology assessments.

OBJECTIVES

To develop algorithms for mapping from measures used in MND clinical studies to allow for future prediction of the five-level EuroQol five-dimensional questionnaire (EQ-5D-5L) utility in populations of patients with MND when utility data have not been collected.

METHODS

Direct mapping models were developed using ordinary least squares and Tobit regression analyses to estimate EQ-5D-5L utilities (based on English tariffs), with ALSFRS-R total, domain, and item scores used as explanatory variables, using patient-level data from a UK cohort study. Indirect mapping models were also used to map EQ-5D-5L domains, using the same variables, along with the Neuropathic Pain Scale and the Hospital and Anxiety Depression Scale for MND using multinomial logistic regression analysis. Goodness of fit was assessed along with predicted values for each mapping model.

RESULTS

The best-performing model predicting EQ-5D-5L utilities used five items of the ALSFRS-R items as explanatory variables in a stepwise ordinary least squares regression. The mean squared error was 0.0228, and the mean absolute error was 0.1173. Prediction was good, with 55.4% of estimated values within 0.1 and 91.4% within 0.25 of the observed EQ-5D-5L utility value. Indirect mapping using the Neuropathic Pain Scale and the Hospital and Anxiety Depression Scale for MND provided less predictive power than direct mapping models.

CONCLUSIONS

This is the first study to present mapping algorithms to crosswalk between ALSFRS-R and EQ-5D-5L. This analysis demonstrates that the ALSFRS-R can be used to estimate EQ-5D-5L utilities when they have not been collected directly within a trial.

Cost-effectiveness of neurostimulation in Parkinson's disease with early motor complications

BACKGROUND

Recent research efforts have focused on the effects of deep brain stimulation of the subthalamic nucleus (STN DBS) for selected patients with mild-to-moderate PD experiencing motor complications.

OBJECTIVES

We assessed the cost utility of subthalamic DBS compared with the best medical treatment for German patients below the age of 61 with early motor complications of PD.

METHODS

We applied a previously published Markov model that integrated health utilities based on EuroQoL and direct costs over patients' lifetime adjusted to the German health care payer perspective (year of costing: 2013). Effectiveness was evaluated using the Parkinson's Disease Questionnaire 39 summary index. We performed sensitivity analyses to assess uncertainty.

RESULTS

In the base-case analysis, the incremental cost-utility ratio for STN DBS compared to best medical treatment was 22,700 Euros per quality-adjusted life year gained. The time to, and costs for, battery exchange had a major effect on the incremental cost-utility ratios, but never exceeded a threshold of 50,000 Euros per quality-adjusted life year.

CONCLUSIONS

Our decision analysis supports the fact that STN DBS at earlier stages of the disease is cost-effective in patients below the age of 61 when compared with the best medical treatment in the German health care system. This finding was supported by detailed sensitivity analyses reporting robust results. Whereas the EARLYSTIM study has shown STN DBS to be superior to medical therapy with respect to quality of life for patients with early motor complications, this further analysis has shown its cost-effectiveness. © 2016 International Parkinson and Movement Disorder Society.

Deep Brain Stimulation for Parkinson's Disease with Early Motor Complications: A UK Cost-Effectiveness Analysis

BACKGROUND

Parkinson's disease (PD) is a debilitating illness associated with considerable impairment of quality of life and substantial costs to health care systems. Deep brain stimulation (DBS) is an established surgical treatment option for some patients with advanced PD. The EARLYSTIM trial has recently demonstrated its clinical benefit also in patients with early motor complications. We sought to evaluate the cost-effectiveness of DBS, compared to best medical therapy (BMT), among PD patients with early onset of motor complications, from a United Kingdom (UK) payer perspective.

METHODS

We developed a Markov model to represent the progression of PD as rated using the Unified Parkinson's Disease Rating Scale (UPDRS) over time in patients with early PD. Evidence sources were a systematic review of clinical evidence; data from the EARLYSTIM study; and a UK Clinical Practice Research Datalink (CPRD) dataset including DBS patients. A mapping algorithm was developed to generate utility values based on UPDRS data for each intervention. The cost-effectiveness was expressed as the incremental cost per quality-adjusted life-year (QALY). One-way and probabilistic sensitivity analyses were undertaken to explore the effect of parameter uncertainty.

RESULTS

Over a 15-year time horizon, DBS was predicted to lead to additional mean cost per patient of £26,799 compared with BMT (£73,077/patient versus £46,278/patient) and an additional mean 1.35 QALYs (6.69 QALYs versus 5.35 QALYs), resulting in an incremental cost-effectiveness ratio of £19,887 per QALY gained with a 99% probability of DBS being cost-effective at a threshold of £30,000/QALY. One-way sensitivity analyses suggested that the results were not significantly impacted by plausible changes in the input parameter values.

CONCLUSION

These results indicate that DBS is a cost-effective intervention in PD patients with early motor complications when compared with existing interventions, offering additional health benefits at acceptable incremental cost. This supports the extended use of DBS among patients with early onset of motor complications.

Combining fractional polynomial model building with multiple imputation

Multivariable fractional polynomial (MFP) models are commonly used in medical research. The datasets in which MFP models are applied often contain covariates with missing values. To handle the missing values, we describe methods for combining multiple imputation with MFP modelling, considering in turn three issues: first, how to impute so that the imputation model does not favour certain fractional polynomial (FP) models over others; second, how to estimate the FP exponents in multiply imputed data; and third, how to choose between models of differing complexity. Two imputation methods are outlined for different settings. For model selection, methods based on Wald-type statistics and weighted likelihood-ratio tests are proposed and evaluated in simulation studies. The Wald-based method is very slightly better at estimating FP exponents. Type I error rates are very similar for both methods, although slightly less well controlled than analysis of complete records; however, there is potential for substantial gains in power over the analysis of complete records. We illustrate the two methods in a dataset from five trauma registries for which a prognostic model has previously been published, contrasting the selected models with that obtained by analysing the complete records only.

Convergent validation of EQ-5D-5L in patients with Parkinson's disease

INTRODUCTION

The European Quality of Life Questionnaire 5 level version (EQ-5D-5L) is a recently updated instrument to assess Health-Related Quality of Life (HRQoL) that has not been validated extensively. The main objective of this study was to evaluate the internal consistency and convergent validation of the EQ-5D-5L in a large sample of subjects with Parkinson's disease (PD).

METHODS

A cross-sectional study was carried out. Consecutive Mexican subjects with PD were included. HRQoL was assessed using the EQ-5D-5L and the PDQ-8. Validity of the EQ-5D-5L was assessed determining its association with clinical ratings of disease severity, as well as correlation with PDQ-8. Additionally, performance was evaluated along predefined groups based on clinical and demographic data of known determinants of quality of life.

RESULTS

A total of 585 patients were included for this study. A strong correlation was found between EQ-5D-5L index and PDQ-8 index (Spearman's correlation coefficient=-0.75; p<0.001). Correlation between EQ-5D-5L index and PDQ-8 index remained strong (-0.60 to -0.78; p values <0.001) through all predefined groups. EQ-5D-5L scored higher in those patients with dyskinesia, wearing off, freezing, postural instability, cognitive impairment or depressive mood (p values <0.001).

CONCLUSION

The EQ-5D-5L is a valid instrument for evaluating HRQoL in PD, performing adequately irrespective of heterogeneous clinical and demographic characteristics, and showing to be sensitive to features of advanced disease and treatment complications.

Deep Brain Stimulation Can Preserve Working Status in Parkinson's Disease

Objectives. Our investigation aimed at evaluating if bilateral subthalamic deep brain stimulation (DBS) could preserve working capability in Parkinson's disease (PD). Materials. We reviewed the data of 40 young (<60 year-old) PD patients who underwent DBS implantation and had at least 2 years of follow-up. Patients were categorized based on their working capability at time of surgery: “active job” group (n = 20) and “no job” group (n = 20). Baseline characteristics were comparable. Quality of life (EQ-5D) and presence of active job were evaluated preoperatively and 2 years postoperatively. Results. Although similar (approximately 50%) improvement was achieved in the severity of motor and major nonmotor symptoms in both groups, the postoperative quality of life was significantly better in the “active job” group (0.687 versus 0.587, medians, p < 0.05). Majority (80%) of “active job” group members were able to preserve their job 2 years after the operation. However, only a minimal portion (5%) of the “no job” group members was able to return to the world of active employees (p < 0.01). Conclusions. Although our study has several limitations, our results suggest that in patients with active job the appropriately “early” usage of DBS might help preserve working capability and gain higher improvement in quality of life.

Mapping from the Parkinson's Disease Questionnaire PDQ-39 to the Generic EuroQol EQ-5D-3L: The Value of Mixture Models

OBJECTIVE

To compare a range of statistical models to enable the estimation of EQ-5D-3L utilities from responses to the Parkinson's Disease Questionnaire 39 (PDQ-39).

METHODS

Linear regression, beta regression, mixtures of linear regressions and beta regressions, and multinomial logistic regression were compared in terms of their ability to accurately predict EQ-5D-3L utilities from responses to the PDQ-39 using mean error (ME), mean absolute error (MAE), and mean square error (MSE), overall and by Hoehn and Yahr stage. Models were estimated using data from the PD MED trial (n = 9123) and assessed on both the estimation data as well as external data from the PD SURG trial (n = 917).

RESULTS

Overall, the differences in the metrics of fit between models were small in both data sets, with performance poorer for all models in PD SURG. The performance across Hoehn and Yahr stages 1 to 3 were also similar, but multinomial logistic regression was found to exhibit less bias and better individual-level predictive accuracy in PD MED for those in Hoehn and Yahr stages 4 or 5. Overall, the multinomial logistic regression reported an ME of 0.038 out of sample and MAEs of 0.128 and 0.164 and MSEs of 0.030 and 0.044 in the estimation and external data sets, respectively. Poorer levels of the mobility domain score of the PDQ-39 were associated with increased odds of reporting problems for all EQ-5D domains except anxiety/depression.

CONCLUSIONS

Finite mixture models with only few components can approximate the distribution of EQ-5D-3L utilities well but did not demonstrate improvements in predictive accuracy compared with multinomial logistic regression in the present data set.

Review of studies mapping from quality of life or clinical measures to EQ-5D: an online database

Systematic literature searches were conducted to identify studies that conducted statistical mapping to predict EQ-5D utilities or responses from any source instrument and reported the estimated algorithms in sufficient detail to allow other researchers to use them to predict EQ-5D in other studies. Ninety studies reporting 121 mapping algorithms met the inclusion criteria. The studies estimated EQ-5D utilities from 80 source instruments. All but two studies included direct utility mapping to predict EQ-5D utilities, while 20 studies (22%) conducted response mapping to predict responses to each EQ-5D domain. Seventy-two studies (80%) explored ordinary least squares regression and 16 (18%) used censored least absolute deviations (CLAD) models. The details of the studies identified are made available in an online database, which will be updated regularly to enable researchers to easily identify studies that can help them to estimate utilities for economic evaluation.