Background: Readmission within 30 days of a COPD hospitalization is a common measure of performance for COPD care. However, most studies of COPD readmission risk have been constrained to a single data source, private payer claims, or Medicare claims data, making it difficult to generalize results from these studies to other populations. The purpose of this study was to examine the risk for readmission within 30 days from time of discharge in patients with COPD using the Healthcare Cost and Utilization Project (HCUP) State Inpatient Database for California for the years 2005-2011. This statewide dataset allows us to consider all readmissions for COPD regardless of age or payer status.
Methods: The total dataset included 28,265,070 visits among 17,918,374 patients over 480 hospitals. We identified patients with a hospitalization, a primary diagnosis related to COPD, age 40 or older, and discharged alive. We found 286,313 hospitalizations that matched this definition and included information on covariates such as comorbidities, age, and insurance status. To characterize the joint associations of these covariates with readmission within 30 days, we used a generalized linear model.
Results: Patients aged 40-64 are more likely to be readmitted to the hospital within 30 days of a COPD-related hospitalization than patients 65 and older. This effect persists after adjustment for patient severity, comorbidities, payer, and demographics. Our model featured an interaction of age with insurance type. We found that younger patients (aged 40-64) on public insurance have the highest readmission rates: 14.77% for Medicare and 16.27% for Medicaid. However, younger patients with private insurance have the lowest readmission rates at 8.25%. Additional significant covariates included whether or not the patient left against medical advice, and diagnoses of congestive heart failure and diabetes. In addition, we found that although admissions for COPD were highest in the winter, this is not true for COPD readmissions, which peak in summer. Also, inpatient mortality for patients admitted for COPD decreased from approximately 3% to 1.25% over the study period.
Conclusion: Our results demonstrate that many of the risk factors for readmission may be dependent on the data source used. Furthermore, many of the strongest predictors are clearly related to the patients themselves. This observation may help explain why prior programs to reduce readmissions have had limited success.