What is quality of life and how do we measure it? Relevance to Parkinson's disease and movement disorders

Pablo Martinez-Martin MD, PhD; Movement Disorders, Version of Record online: 2 DEC 2016 DOI: 10.1002/mds.26885

The objective of this review is to present the conceptual framework, the measures, and some of their most relevant applications in the field of Parkinson's disease and movement disorders. Health-related quality of life is a subjective, individual, and multidimensional construct, and its main dimensions are physical, mental, and social, besides global perceptions of health and personal domains. Health-related quality of life measurement is carried out by means of questionnaires or scales, ideally self-applied by patients, and has a diversity of important applications for clinical practice, research, and health policy.

The origins of the quality of life (QoL) concept are ancient and, in some way, controversial from the beginning. Around 4 centuries before Christ, Greek philosophers proposed the “good life” as a vital goal, an ancestry term of the current notion of QoL. Aristippus (435-350 BC) and the hedonists defended the achievement of pleasure as the basis of happiness, a view later nuanced by Aristotle (384-322 BC), who moved the concept of happiness to the pursuit of activities focused on more worthy objectives and values (eudaimonia: well-being, happiness). The controversy between hedonists and eudaimonics, influenced by new theoretical contributions and inspirations, has in some way continued until the present.

In the setting of movement disorders, it is recommended to increase the number of clinical trials focused on HRQoL, with HRQol acting as the mainendpoint of the study. For obtaining more complete information about HRQoL status and change, a combination of generic and specific measures is recommended. The contents of the generic scales may not be relevant for specific conditions, and their responsiveness may be low; however, the specific instruments can overlook important aspects of general health. For example, in the setting of PD, the SF-36 does not include evaluation of self-image or stigma, whereas the PDQ-39 does not include assessment for energy/fatigue. Finally, for the correct use and interpretation of outcomes, it is advisable to keep in mind the potential limitations that HRQoL instruments, their application, or analysis may present.