Self-rated health mediates the association between functional status and health-related quality of life in Parkinson's disease

Aims and objectives: To explore whether self-rated health acts as a potential mediator in the association between functional status and health-related quality of life in Parkinson's disease.

Background: Older persons (as most patients with Parkinson's disease are) who reported poor self-rated health compared with those with excellent self-rated health were two-and-a-half times more likely to have experienced a decline in functional ability.

Design: Cross-sectional.

Methods: Socio-demographic and clinical data of the patients (n = 176) were obtained during a structured interview and from medical records. Functional status was measured with the Unified Parkinson's Disease Rating Scale (total score), self-rated health with the first item of the Short-Form 36-item Health Survey Questionnaire and health-related quality of life with the disease-specific questionnaire called the Parkinson's Disease Quality of Life Questionnaire-39. Multiple linear regression analyses and the Sobel test were employed to assess mediation.

Results: Self-rated health seems to have a mediating effect on the association between functional status and health-related quality of life. The Sobel test confirmed an indirect effect of functional status via self-rated health on health-related quality of life and showed a statistically significant indirect effect of functional status on health-related quality of life via self-rated health against the direct route without the mediator.

Conclusions: Self-rated health partially mediates the deteriorating effect of functional status on health-related quality of life.

Relevance to clinical practice: Supportive and adaptation psychosocial intervention programmes leading to restored self-rated health may enhance the quality of life regardless of disability in Parkinson's disease.