Abstract: Objective To examine the prevalence, comorbidity patterns, and healthcare utilization determinants of chronic diseases among middle-aged and elderly agricultural workers in China, providing evidence for targeted chronic disease prevention strategies. Methods Data were extracted from the China Health and Retirement Longitudinal Study (CHARLS) for 2018 and 2020. Systematic clustering, association rule mining, and generalized linear mixed-effects models were used to analyze comorbidity patterns and healthcare utilization factors. Results Among 6 295 agricultural workers, the comorbidity prevalence increased significantly from 51.52% (95% CI: 50.27%-52.76%) in 2018 to 55.87% (95% CI: 54.63%-57.10%) in 2020 (χ²=23.98, P<0.01). Arthritis/rheumatism (2018: 33.95%→2020: 35.46%), digestive disorders (27.28%→29.29%), and hypertension (26.93%→30.10%) constituted the top three chronic conditions. Cluster analysis identified three stable comorbidity patterns: metabolic-circulatory, respiratory-hepatorenal multiorgan, and neuro-oncological complexes. Generalized linear mixed models revealed that outpatient utilization was associated with survey year (2020: OR=1.32), depressive symptoms (OR=1.21), high physical activity (OR=1.17), male sex (OR=0.84), self-rated health (fair: OR=0.53;good: OR=0.32), and comorbidity count (1 condition: OR=1.65;2: OR=2.10;≥3: OR=3.40). Inpatient service, utilization was associated with survey year (OR=1.33), age (55-<65: OR=1.18;65-<75: OR=1.51;≥75: OR=2.35), depressive symptoms (OR=1.17), high physical activity (OR=0.83), self-rated health (fair: OR=0.42;good: OR=0.25), and comorbidity count (1: OR=1.70;2: OR=2.33;≥3: OR=3.85). Conclusions The prevalence of comorbidities among middle-aged and elderly agricultural workers is increasing significantly, with arthritis/rheumatism, digestive disorders and hypertension constituting the predominant spectrum of comorbidities. Healthcare service utilization is driven by multifactorial determinants. This suggests the need to establish a prevention and control system based on comorbidity networks and risk gradient interventions. This system would enhance the effectiveness of chronic disease management through optimizing health behaviors and intelligent monitoring, and provide a theoretical basis for developing precise prevention and control strategies targeting special occupational groups.

Key words: Chronic disease comorbidity, Middle-aged and elderly, Agricultural workers, Healthcare utilization, Association analysis