The assessment of psychological well-being in systemic sclerosis: a clinimetric validation

Background: The assessment of psychological well-being has been largely neglected in clinical settings, particularly in patients with systemic sclerosis (SSc), where the focus of clinical attention was mainly on symptoms. This is the first study in which the validity, reliability, and sensibility of two patient-reported outcome measures (PROMs) of psychological well-being, the five-item World Health Organization Well-Being Index (WHO-5) and the six-item version of the Ryff’s Psychological Well-Being Scales (PWB-6), have been tested according to clinimetric criteria to determine their current and potential clinical applications in SSc patients. Methods: A cross-sectional study was conducted involving 219 patients with a diagnosis of SSc. Rasch and Mokken analyses were performed to assess the clinimetric properties of the two PROMs and determine their clinical utility. Results: All items of WHO-5 and PWB-6 fitted the Rasch model, had an optimal scalability, and the dimensionality analyses yielded less than 5% of significant t-tests, thus indicating that the two PROMs were unidimensional measures. Person separation reliability indices revealed acceptable internal consistency and inspection of the person-item distribution map showed that WHO-5 and PWB-6 were reasonably well-targeted for use with SSc patients. Conclusions: Findings indicate that WHO-5 and PWB-6 are valid indices of psychological well-being that may provide unique prognostic information and help researchers and clinicians tailor personalized treatment strategies. The two PROMs can be used jointly but for different clinical purposes. WHO-5 is particularly suitable to assess the degree of subjective vitality, a positive feeling of aliveness and energy that may help SSc patients cope with their illness. The PWB-6 can be used to identify unique experiences of psychological well-being that may help SSc patients not only cope with their feelings of loneliness and uncertainty but also experience a meaningful life despite the progression of disease. In clinical research and daily practice, the baseline and follow-up use of WHO-5 and PWB-6 may thus lead to a substantial improvement in the quality of care of patients with SSc. Given the cross-sectional design of the present investigation, future prospective studies are, however, recommended to further assess the predictive validity and prognostic utility of the two PROMs.