Serum IgA, IgG, and IgM as predictive biomarkers for 90-day readmission outcomes in elderly patients with pulmonary tuberculosis complicated by COPD

Elderly patients with pulmonary tuberculosis (TB) and chronic obstructive pulmonary disease (COPD) face high 90-day readmission rates. The prognostic value of serum immunoglobulins (IgA, IgG, IgM) in this population is unknown. To evaluate whether serum IgA, IgG, and IgM levels can predict 90-day readmission in elderly patients with pulmonary TB and COPD. This retrospective cohort study analyzed data from elderly patients with pulmonary TB and COPD admitted between January 2019 and December 2023. Patients were divided into favorable prognosis (no readmission) and poor prognosis (readmission within 90 days) groups. Serum levels of IgA, IgG, and IgM were measured, and multivariate logistic regression was used to assess their predictive value. ROC curves evaluated predictive performance. Serum IgA, IgG, and IgM levels were significantly different between the two groups (P < 0.001). Multivariate regression revealed that these immunoglobulins were independent predictors of 90-day readmission. The combination of IgA, IgG, and IgM had an area under the curve (AUC) of 0.89 (95% CI: 0.86–0.93), with 81% sensitivity and 84% specificity. Serum IgA, IgG, and IgM may aid in identifying elderly TB-COPD patients at risk for 90-day readmission, with the combined model showing improved predictive accuracy—though prospective validation is needed.