Psychometric properties of the mutuality scale in Swedish dyads with Parkinson's disease
Despite Parkinson′s disease (PD) is primarily considered as a movement disorder, cognitive impairment and depression are two of the most common and important non‐motor symptoms and main causes of increased functional dependency.1 It is likely for most PD‐patients living in a partnership to confront a wide range of difficulties during the unpredictable and inevitable course of PD. Such difficulties, worries and unmet needs may further result in increased stress, caregiver burden and impaired quality of life (QoL).2 An important aspect of the caregiving situation is the experience of marital satisfaction, close relationship and the ability to find gratification and meaning in the relationship with the significant other.5 Mutuality as a concept is widely used to signify the relationship's quality and can be described as characteristics of the interpersonal relationship between care dyads.6 Research to date suggests that high quality of the relationship can be an important protective factor in progressive conditions such as PD and conversely, low quality relationship can be a risk factor for mood disturbance, decreased emotional well‐being, depression and increased caregiving burden.6 The 15‐item mutuality scale (MS), developed in the USA, is the most widely used scale to assess the quality of relationship.6 The concept mutuality is defined as “positive quality of the relationship between caregiver and care receiver” and has four dimensions: love and affection, shared pleasurable activities, shared values and reciprocity.11 The scale is often used as a global measure and was initially developed through content analysis with a clear link to the concept of mutuality rather than statistical approaches such as factor analysis.6 So far, to the best of our knowledge, no psychometric assessment or factorial analysis has been reported for the utility of the MS in PD‐patients. Availability and use of the mutuality rating scale may provide a way to screen and facilitate early detection of high‐risk care dyads and improve our understanding of changes in mutuality regarding disease progression and social exchanges. Additionally, it is beneficial to identify different dimensions within the MS in order to enable gathering more precise information of the impact on different outcomes in research settings. Therefore, the aim of this study was to validate and assess psychometric properties of the Swedish version of the MS to evaluate the quality of relationship between PD‐patients and their partners.