Psychometric Characteristics of the Mutuality Scale in Stroke Patients and Caregivers

Purpose: The Mutuality Scale (MS) is composed of four theoretically derived factors (love, shared pleasurable activities, shared values, and reciprocity), but this structure has never been confirmed. Also, research involving the patient's perspective on the MS is limited. In this study, we tested the factorial structure of the MS and its reliability in stroke patients and caregivers. Design and Method: Cross-sectional, with a follow-up after 15 days for test-retest reliability. A total of 248 stroke patients and 163 stroke caregivers completed the MS. Stroke patients and their caregivers were enrolled in 10 rehabilitation hospitals across Italy. MS factorial structure was analyzed using confirmatory factor analysis; internal consistency reliability was evaluated with Cronbach's a and model-based internal consistency index; test-retest reliability was evaluated with intraclass correlation coefficient. Results: Confirmatory factor analysis supported the four-factor structure of MS in its patient and caregiver version (CFI = 0.94; RMSEA = 0.06, for both). Cronbach's as and model-based internal consistency index were >0.90 and intraclass correlations ranged between 0.66 and 0.93 in MS patient and caregiver version. Implication: This study tested the theoretical dimensions of the MS in stroke patients and their caregivers. From a scientific and clinical point of view, an assessment of stroke patient and caregiver mutuality would allow dyadic approaches to data analysis and care that account for the nonindependence between the stroke patient and the caregiver.