Long-Term Medicare Use and Cost Patterns Associated with Type-Specific Sentinel Injury Episodes

Background Each year, 6 million elders require medical attention due to injury. Although estimates suggest that Medicare costs for older injured adults exceed 8 billion dollars annually, this most likely underestimates true costs given the potential for injury to complicate preexisting healthcare needs. In response, this study used multiple years of survey and administrative claims data to longitudinally examine Medicare use and costs among older adults experiencing type-specific sentinel injury.

Methods Data from the Medicare Current Beneficiary Survey and Medicare Non-Response Files (1998-2005) were used to construct longitudinal histories spanning up to five years capturing Medicare monthly service use (n=94,403 person-months). Type-specific injuries were identified using ICD-9-CM codes following the Barell Injury Diagnosis Matrix. Using a case cross-over design to control for selection effects, multilevel models for change were estimated to examine the long-term effect of type-specific sentinel injury episodes on Medicare cost and use patterns.

Results Findings suggest injury increases Medicare use and cost patterns long after the injury episode concludes. Injury of any type significantly raised Medicare costs in comparison to average pre-injury costs for more than two years following the index event. Fractures, internal injuries, open-wounds and contusions were associated with the longest run of increased costs. Although average monthly hospital admission rates increased nearly 60% post-injury, use of skilled nursing, home health and hospice care comprised the bulk of increased Medicare services.

Conclusions The long-term increase in Medicare services following injury suggests greater attention to the complex dynamic between injury, comorbidity, frailty and disability is needed.