LAUSR

Objective: To investigate the longitudinal changes in principal readmission diagnoses within 30 days after hospitalization for acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Study Setting: Medicare claims data, 2010–2012. Study Design: Retrospective cohort study. Data Collection Methods: We identified AECOPD hospitalizations aged 65 years and above, and examined the principal 30-day readmission diagnoses (respiratory related, cardiac related, and other conditions). We also constructed Joinpoint regression models to test whether patients with each of the 3 major readmission conditions had a unique temporal pattern of readmission during the 30-day period. Principal Findings: Among 76,697 index hospitalizations with AECOPD, 14,090 (18.4%) were readmitted within 30 days. Respiratory-related conditions accounted for 55% of readmissions. The proportion of respiratory-related conditions as the readmission diagnosis decreased from postdischarge day 1 to day 8 (4.0% decrease), and then increased thereafter (13.2% increase; P=0.06). Cardiac-related conditions had a similar nonlinear trend with an inflection point at day 6 (P=0.02), with a subsequent downward trend from day 22 (P=0.01). By contrast, the other conditions increased from day 1 to day 6 (15.0% increase), and then significantly decreased (28.8% decrease; P=0.04). Conclusions: The proportions of principal discharge diagnosis of readmission changed significantly at around postdischarge day 7. Our findings advance research into identification of the underlying mechanisms and development of targeted interventions to prevent readmissions.