The association between treatment burden and quality of life in older adults with multimorbidity: the mediating role of personal mastery and the moderating role of social support-a cross-sectional study in China.

BACKGROUND: Treatment burden is associated with health-related quality of life (HRQoL) in multimorbidity, but its psychological and social correlates in older adults remain unclear. This study examined whether personal mastery was statistically linked to the association between treatment burden and HRQoL and whether social support moderated the association between treatment burden and personal mastery. METHODS: A cross-sectional survey was conducted among 470 outpatients aged 60 years and older with multimorbidity in Jiangsu Province, China. Treatment burden, personal mastery, social support, and HRQoL were assessed using validated scales. Pearson correlations and PROCESS Model 7 with 5,000 bootstrap resamples were used, adjusting for age, BMI, sex, income, and education. RESULTS: Treatment burden was negatively associated with personal mastery (b = -0.1185, p < 0.001), and the treatment burden × social support interaction was significant (b = 0.0056, p < 0.001). Personal mastery was positively associated with PCS (b = 0.4064, p = 0.005) and MCS (b = 0.3894, p = 0.028). Treatment burden showed a negative direct association with PCS (b = -0.1417, p < 0.001) but a positive direct association with MCS (b = 0.3639, p < 0.001). The indices of moderated mediation were significant for PCS (index = 0.0023, 95% CI [0.0006, 0.0042]) and MCS (index = 0.0022, 95% CI [0.0002, 0.0047]). CONCLUSION: Greater treatment burden was associated with poorer physical HRQoL and showed negative indirect associations with physical and mental HRQoL through lower personal mastery. These indirect associations were weaker at higher social support.