Dementia, Systemic Biomarkers, and Risk of 30-Day Readmission After Pneumonia: A Multi-Center Cohort Study

Dementia is a significant risk factor for adverse health outcomes, including pneumonia-related hospitalizations and readmissions. While comorbidities have been shown as predictors of poor pneumonia outcomes, the interplay between chronic comorbidities and acute physiological conditions, reflected by systemic biomarkers, remains underexplored. This study investigates the independent and joint effects of dementia and acute biomarkers on 30-day readmission risk following pneumonia hospitalization.

We conducted a multicenter cohort study using data from three hospitals within the Taipei Medical University Clinical Research Database. Patients aged ≥45 years hospitalized for pneumonia between 2014 and 2021 were included. Dementia status was identified via ICD-9/10 codes, and acute systemic biomarkers were measured at the time of emergency department presentation. The primary outcome was 30-day all-cause readmission. Multivariable logistic regression assessed independent associations, while joint-effects models examined the combined impact of dementia with biomarker abnormalities and comorbidities.

Among 11,989 patients, 6.7% experienced 30-day readmission. Dementia was independently associated with readmission (adjusted OR: 1.31, 95% CI: 1.07-1.61). Other significant predictors included abnormal hemoglobin (OR: 1.55), creatinine (OR: 1.42), glucose (OR: 1.32), and comorbidities such as cancer, chronic kidney disease, and diabetes mellitus. Joint-effects models showed that dementia amplified the impact of abnormal biomarkers, eg, patients with low hemoglobin and dementia had an OR of 1.98 compared to those with normal hemoglobin and no dementia.

Dementia and acute biomarker abnormalities independently and synergistically increase 30-day readmission risk after pneumonia hospitalization, underscoring the need for integrated management strategies targeting both cognitive and systemic health.