Review
Determinants of health-related quality of life in Parkinson’s disease: A systematic review

https://doi.org/10.1016/j.parkreldis.2010.08.012Get rights and content

Abstract

This systematic review critically evaluates the literature to identify the demographic and clinical factors that predict the health-related quality of life (HRQOL) of people with Parkinson’s disease (PD). Understanding how these factors relate to HRQOL in people with PD may assist clinicians minimise the functional and social impact of the disease by optimising their assessment and clinical decision making processes. A tailored search strategy in six databases identified 29 full-text reports that fulfilled the pre-defined inclusion and exclusion criteria. The quality of included studies was assessed by two independent reviewers using a customised assessment form. A best-evidence synthesis was used to summarise the demographic and clinical factors that were examined in relation to HRQOL. Depression was the most frequently identified determinant of HRQOL in people with idiopathic PD. Disease severity and disease disability were also found to be predictive of poor HRQOL outcomes in many studies. The motor symptoms that contributed most often to overall life quality were gait impairments and complications arising from medication therapy. To minimise the impact of PD on HRQOL, it may be necessary to consider the extent to which demographic factors and motor and non-motor symptoms contribute to life quality.

Introduction

This paper presents a systematic review and critical evaluation of studies that have examined factors that contribute to health-related quality of life (HRQOL) in people with idiopathic Parkinson’s disease (PD). Quality of life (QOL) can be defined as “an individual’s perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns” (p. 1405) [1]. Health-related QOL refers to the health dimension of QOL, taking into account aspects of physical health, emotional status and cognition [2]. Knowing which factors predict HRQOL may assist clinicians to focus their assessments and select treatment strategies to minimise the functional and emotional consequences of PD.

Despite a rapid increase in the number of studies on HRQOL, it remains unclear which demographic and clinical factors are the main predictors of life quality in people with PD. There have been two previous systematic reviews examining HRQOL in PD with different objectives. The review by Den Oudsten et al. [3] focused primarily on the conceptual rigor of QOL studies in people with PD and concluded that the term was often used inappropriately. Post et al. [4] explored the factors that predicted changes in motor impairment, disability and QOL over the disease course and did not find any prognostic factors for QOL. Nevertheless, both reviews showed wide variation in whether factors such as age, education, disease duration and gait dysfunction contributed to QOL [3], [4].

The current review critically evaluates literature on the demographic and clinical factors that contribute to HRQOL in people with idiopathic PD. Demographic factors refer to participant characteristics such as age, sex and employment status [3]. Clinical factors include items such as disease severity and disease duration and the motor and non-motor PD symptoms. A qualitative appraisal of the evidence describing the factors that predict HRQOL in people with PD will also be presented.

Section snippets

Search strategy

A search strategy was developed to identify published studies on the predictors of HRQOL in PD. A literature search was conducted in May 2010 in six online databases indexing journals related to topics in health, medicine and allied health. The databases included Medline (from 1960), CINAHL (from 1982), Embase (from 1966), Web of Science (from 1960), PsychINFO (from 1960) and Scopus (from 1960). A tailored search strategy was designed to capture key search terms. The term “Parkinson’s disease”

Search yield

The initial electronic search yielded 1387 published articles (Fig. 1). After removing duplicates and reviewing the titles and abstracts, 85 were considered suitable for further consideration. Hand searching of references from relevant studies identified an additional 18 articles. Following the application of pre-defined inclusion and exclusion criteria, 29 full-text reports were identified for inclusion in the systematic review, details of which are summarised in Table 2. Arbitration from the

Discussion

The most frequently identified significant determinant of HRQOL in people with idiopathic PD was the presence of depressive symptoms. This parallels findings by Schrag [44] and Den Oudsten et al. [3] who reported that depression was the main factor associated with poor HRQOL and the perception that PD has a negative impact on functional ability. Increased disease severity and disability were also frequently found to predict poorer HRQOL in people with this progressive and debilitating

Conclusion

Individuals with PD who are depressed, have more advanced disease and have high levels of disability are most likely to experience poor HRQOL. To minimise the functional consequences of PD, it may be beneficial for clinicians to consider how demographic factors and motor and non-motor symptoms contribute to HRQOL. The extent to which the disease affects the HRQOL of families and caregivers of people with PD also warrants further investigation.

Acknowledgements

The authors gratefully acknowledge the valuable contributions of Mary Danoudis and Brook Galna for their thoughtful review of this manuscript.

Ms Sze-Ee Soh is a Physiotherapist and a PhD student at the Melbourne School of Health Sciences in The University of Melbourne.

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    Ms Sze-Ee Soh is a Physiotherapist and a PhD student at the Melbourne School of Health Sciences in The University of Melbourne.

    Professor Meg E. Morris is a Professor of Physiotherapy, Associate Dean and Head of the Melbourne School of Health Sciences at The University of Melbourne.

    Dr Jennifer McGinley is a Physiotherapist, Group Leader of Gait Analysis Research at the Murdoch Childrens Research Institute and Senior Research Fellow at the Melbourne School of Health Sciences in The University of Melbourne.

    The review of this paper was entirely handled by the Co-Editor-in-Chief, Prof. Z.K. Wszolek.

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