Multimorbidity and quality of life: examining the pathways through loneliness, adl, iadl, and depressive symptoms

Abstract Background. Multimorbidity, defined as two or more chronic conditions, negatively affects quality of life. However, little is known about the underlying pathways leading from multimorbidity to lower quality of life (QoL). Objective. The objective of this paper was to examine multiple potential mediating factors (loneliness, Activities of Daily Living [ADL], Instrumental Activities of Daily Living [IADL], depressive symptoms) in the relationship between multimorbidity and quality of life. Furthermore, we explored moderated mediation patterns by age, gender, and education. Methods. Longitudinal data were drawn from five waves (from 2011 to 2020) of the Survey of Health, Ageing and Retirement in Europe (SHARE). We included 37,082 individuals aged 50 years and older in the analyses. The predictor (multimorbidity) and covariates were measured four and the mediators two years before the QoL outcome (CASP-12). Confounder-adjusted mediator and outcome models were fitted using mixed-effects models. The total association was decomposed into direct and indirect pathways applying causal mediation analyses with Monte-Carlo simulations. Results. Multimorbidity was associated with lower QoL four years later; 2.12%, 6.17%, and 19.90% of the association was mediated by ADL, IADL, and depressive symptoms, respectively. Mediation by loneliness was not significant. Generally, the mediation patterns were more pronounced in women and individuals with tertiary education as compared to primary and secondary. Differential mediation by age quartiles did not reveal a clear pattern. Conclusions. The results showed that depressive symptoms were the most important mediator between multimorbidity and QoL, with ADL and IADL also playing an important role.