Comorbidity patterns and inpatient expenditure among patients with coronary heart disease in China

Coronary heart disease (CHD) often co-occurs with other chronic conditions. This increases care complexity and hospital costs. Most previous studies have relied on single diseases or simple comorbidity counts. Less is known about whether different multimorbidity patterns are associated with different levels and structures of inpatient expenditure. We aimed to identify comorbidity patterns among middle-aged and older inpatients with CHD and to examine their associations with hospital costs.

We conducted a retrospective study using electronic health record data from a tertiary hospital in Shanxi Province, China, from 2020 to 2024. Patients aged 45 years or older with a principal discharge diagnosis of CHD (ICD-10: I20-I25) were included. The outcome was total inpatient expenditure per admission. Latent class analysis was applied to 14 comorbidities with prevalence of at least 1%. We then used generalised linear models with a gamma family and log link to examine the association between latent classes and inpatient expenditure, adjusting for sociodemographic and clinical covariates.

Among 33,044 patients used for pattern identification, 85.16% (28,140) had at least one included comorbidity. Five classes were identified: low comorbidity (39.89%), vascular disease (5.20%), hypertension-dominant (42.27%), diabetes-renal (3.16%), and cardiac dysfunction (9.48%). Compared with the low-comorbidity class, all other classes were associated with higher inpatient expenditure, with the largest increases observed in the cardiac dysfunction class (ER = 1.33, 95% CI: 1.30-1.36) and the diabetes-renal class (ER = 1.27, 95% CI: 1.23-1.32). Predicted mean expenditure was highest in the cardiac dysfunction class ($2,615.77; 95% CI: 2,562.30-2,669.24) and the diabetes-renal class ($2,502.99; 95% CI: 2,421.49-2,584.49), compared with $1,964.85 (95% CI: 1,943.54-1,986.16) in the low-comorbidity class. Medical consumables accounted for the largest share of expenditure in all groups, while the cardiac dysfunction class had the highest proportions of diagnostic and medication costs.

Multimorbidity was highly prevalent among middle-aged and older inpatients with CHD. Distinct comorbidity patterns were associated with different levels and structures of inpatient expenditure. These findings may help inform more tailored care planning and more refined payment adjustment in tertiary inpatient settings.