Medicare HMO penetration and mortality outcomes of ischemic stroke

To examine associations between Medicare health maintenance organization (HMO) penetration and stroke mortality outcomes among older persons.

Panel analysis of nationally representative secondary data from 1993 to 1998.

The first analysis sample included ischemic stroke hospitalizations among older persons in the Nationwide Inpatient Sample; the second included county-level ischemic stroke deaths in the National Vital Statistics System. The 2 samples were merged with the HMO enrollment data and the 2001 Area Resource File. The 2 outcomes were in hospital death status and county-level population ischemic stroke death rates among older persons; the 2 utilization variables were length of hospital stay for ischemic stroke and proportion of ischemic stroke deaths occurring in hospitals. The 3 key explanatory variables were county-level Medicare total, independent practice association, and nonindependent practice association HMO penetration. Ordinary least squares analysis with hospital or county fixed effects was used in estimation.

Medicare HMO penetration was not associated with the 2 ischemic stroke mortality outcomes (P > .05). Increases in Medicare total and independent practice association HMO penetration were associated with a significant shift in a higher proportion of stroke deaths from hospitals to nursing homes or residences (P < .05). Medicare HMO penetration was negatively associated with length of stay, although this was not statistically significant (P > .05).

Increased Medicare HMO penetration was associated with a shift in ischemic stroke deaths from hospitals to nonhospital settings. The effect of Medicare HMO penetration on quality of stroke care needs further research.