Social activity as mediator between social support and psychological quality of life among people with rare diseases: A national repetitive cross-sectional study

Background: Considerable proportion of people with rare diseases (RDs) have suffered from severe mental health problems. However, specific attention on the psychological quality of life (QoL) of people with RDs is sparse. Evidence documented the benefits of social support and social activity on recipients' mental health and overall QoL, but no corresponding study answered how both social support and social activity work on the psychological QoL among people with RDs. This study aims to report the psychological QoL and evaluate the mediating role of social activity between social support and psychological QoL among people with RDs.& nbsp;Methods: Data were from two national repetitive cross-sectional surveys, conducted in China in February 2016 and February 2018. In this study, eligible people were those aged 18 or above and had clinical-diagnosed RDs. Psychological QoL was measured by the subdomain of World Health Organization Quality of Life: Brief Version. Social support was measured by the Medical Outcomes Study Social Support Survey. Social activity was measured with seven items selected from the measurement on leisure activities used by the Chinese General Social Survey. Using the mediation model, we assessed the direct and indirect (via social activity) association between social support and psychological QoL, both on overall and subtypes of RDs. We controlled for a variety of potential socioeconomic and demographic confounding factors.& nbsp;Results: Of the 2403 adults studied, their average score of psychological QoL was 42.49 out of 100. The psychological QoL was directly associated with received emotional/information support (coefficient = 0.159, 95% CI = [0.093, 0.231], p < 0.0001) and positive social interaction (coefficient = 0.159, 95% CI = [0.097, 0.221], p < 0.0001). The psychological QoL was indirectly (via social activity) associated with received tangible support (coefficient =-0.035, 95% CI = [-0.046,-0.025], p < 0.0001) and positive social interaction (coefficient = 0.056, 95% CI = [0.040, 0.074], p < 0.0001). Above results by subtypes of RDs were also reported. Limitations: The causal inference was not able to be investigated due to the cross-sectional study design.& nbsp;Conclusion: People with RDs suffered from a low psychological QoL. Social activity mediated the association between social support and psychological QoL, but its mediating role depended on the subscales of social support as well as the subtypes of RDs. Customized measures based on the type of RDs and support that will be provided could perhaps improve the psychological QoL of people with RDs directly and indirectly.