Network dynamics of metabolic disease continuum in older adults: a 7-year longitudinal cohort study in China

Metabolic diseases co-occur as multimorbidity rather than presenting in isolation. This study aims to estimate the evolution and patterns of multimorbidity networks centered on metabolic disease continuum (MDC) among old adults to understand the accumulation over time and identify factors associated with multimorbidity. We conducted a longitudinal study involving individuals aged ≥ 65 years who underwent examinations at the Second Affiliated Hospital of Chongqing Medical University between 2016 and 2022. Network analysis was applied to analyze the multimorbidity patterns over time between 6 MDCs (including diabetes, osteoporosis, Vitamin D deficiency, obesity, fatty liver, and hyperuricaemia) and 20 other non-communicable diseases (NCDs). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to quantify the strength of association for all diseases. Kaplan–Meier curves, univariate Cox regression, and multivariable Cox regression were used to evaluate the risk of multimorbidity and its risk factors in patients with MDCs. Among the 10,052 participants, MDC-centered multimorbidity networks became more interconnected over time. Hypertension showed the strongest and progressively increasing correlation with MDCs (male: r = 0.177 to 0.209; female: r = 0.189 to 0.220). Patients with MDCs had a higher risk of developing fatty liver (first examination: OR = 5.21, 95% CI: 4.52–6.00; last examination: OR = 8.87, 95% CI: 7.28–10.81). In addition, diabetes (HR = 1.322, 95% CI: 1.245–1.403), vitamin D deficiency (HR = 1.394, 95% CI: 1.107–1.754), obesity (HR = 1.793, 95% CI: 1.601–2.007), and fatty liver (HR = 1.308, 95% CI: 1.224–1.398) were associated with an increased cumulative risk of multimorbidity. Among patients with MDCs, female sex (HR = 1.156, 95% CI: 1.108–1.205), older age (HR = 1.004, 95% CI: 1.001–1.007), higher BMI (HR = 1.067, 95% CI: 1.059–1.074), higher education (HR = 1.084, 95% CI: 1.036–1.135), salty diet (HR = 1.353, 95% CI: 1.276–1.435), and moderate drinking (HR = 1.218, 95% CI: 1.080–1.373) further increased multimorbidity risk. MDC-centered multimorbidity networks became increasingly interconnected, with hypertension consistently showing the strongest association. Specific metabolic disorders (diabetes, Vitamin D deficiency, obesity, fatty liver, and hyperuricaemia) and demographic-behavioral determinants (female, older age, higher BMI, drinking and salty diet) significantly accelerated multimorbidity progression.