Venue: The Fuqua School of Business, Duke University, 1 Towerview Drive, Durham, NC 27708-0120
Presentation
Adverse Events for Hospitalized Medicare Patients: Is there a difference between HMO and FFS enrollees?
Objective. This study examines the likelihood of occurrence of adverse events among two groups of hospitalized elderly Medicare beneficiaries -- those enrolled in HMOs (i.e., Medicare Advantage plans) versus those enrolled in Fee-for-Service (FFS) insurance plans. Due to the hypothesis that HMOs bear more of the cost of adverse events and more managerial control of physicians, fewer adverse events are expected. However, based on findings in previous studies, it is possible that HMOs would calculate more savings by contracting with lower quality hospitals where the rate of adverse events would be higher. By choosing lower quality hospitals, HMOs thus could indirectly contribute to higher rates of adverse outcomes for their patients. Finally, it is possible that HMOs would select patients more carefully for risky, elective procedures. In view of these counteracting incentives, it is not possible to predict a priori whether HMO enrollees are likely to incur a higher rate of adverse events than FFS patients.
Methods. The study includes all hospitalized elderly Medicare patients in the State of Florida in 2002. Using HCUP data of the Agency for Health Care Research and Quality (AHRQ), several discharge level variables are extracted including AHRQ's Patient Safety indicators (PSI) to indicate an adverse event. The study included 9 non-birth related PSIs, and used logistic regression models to predict the likelihood of an adverse event among Medicare HMO versus Medicare FFS patients at risk. Several covariates including patient demographics and comorbidities, as well as hospital quality, are included.
Results. The study shows that, after adjusting for hospital quality, Medicare HMO patients were at higher risk of adverse outcomes than Medicare FFS patients for 'accidental puncture or laceration', 'post operative respiratory failure', and for 'iatrogenic pneumothorax'. For 'postoperative sepsis', although there was no net effect for an average hospital, HMO patients were particularly affected by low quality hospitals. We also found that 'accidental puncture and laceration' and 'selected infections due to medical care' were more consistently likely to increase with poorer hospital quality.
Conclusions: This exploratory study demonstrates how a number of available databases and tools applied to assess differences between subpopulations related to insurance coverage can be tested for effects on adverse outcomes. At the current state of development, there are enough concerns raised about the higher rate of adverse events among hospitalized Medicare HMO vs. FFS patients to motivate more investigation. The concerns about adverse events is heightened by recent increases in enrollment in Medicare Advantage plans, and by the payment regulations to penalize adverse events in the FFS population, but no attention has yet been extended to protecting HMO enrollees.