Impact of Multimorbidity on Quality of Life: The Mediation Role of Intrinsic Capacity – Evidence from the WHO ICOPE Pilot Program in Lianyungang of China

Introduction: Quality of life (QoL) is associated with multimorbidity, but the underlying mechanisms remain poorly understood. This study aimed to explore the association between multimorbidity and QoL, focusing on intrinsic capacity (IC) as a mediator. Methods This cross-sectional study was conducted under the World Health Organization (WHO) Integrated Care for Older People (ICOPE) pilot program in China, Lianyungang. Multimorbidity was classified by clinicians' experience, Charlson Comorbidity Index, and Cumulative Illness Rating Scale for Geriatrics. QoL was assessed using EQ-5D-3L. IC was assessed based on the WHO’s guidelines for ICOPE. Logistic regression was used to calculate the correlation between multimorbidity and QoL. Mediation model was further constructed to assess the mediating role of IC. Results This study recruited 468 adults aged ≥ 60 years (207 males [44.2%]). In logistic regression, each additional condition in multimorbidity is associated with a 22% elevated risk of reduced QoL (adjusted for gender, age, IC, marital status, education, nursing home resident status). Specifically, compared to Q1 (multimorbidity number = 0), the risk of poor QoL increased by 148% (95% CI: 1.39–4.43, p  = 0.002) in Q2 (number = 1), 172% (95% CI: 1.48–5.01, p  = 0.001) in Q3 (number = 2–3), and 194% (95% CI: 1.57–5.50, p  < 0.001) in Q4 (number ≥ 4), respectively. Additionally, mediation analysis showed that IC mediated 25.90% of the multimorbidity-QoL association ( p  < 0.001). Conclusion Our findings suggest that multimorbidity was a risk factor for poorer QoL. IC was an cost-effective strategy for identifying QoL and mediated the multimorbidity-QoL association.