Challenges in assessing hospital-level stroke mortality as a quality measure: comparison of ischemic, intracerebral hemorrhage, and total stroke mortality rates.

BACKGROUND AND PURPOSE Public reporting efforts currently profile hospitals based on overall stroke mortality rates, yet the "mix" of hemorrhagic and ischemic stroke cases may impact this rate. METHODS Using the 2005 to 2006 New York state data, we examined the degree to which hospital stroke mortality rankings varied regarding ischemic versus hemorrhagic versus total stroke. Observed/expected ratio was calculated using the Agency for Healthcare Research and Quality Inpatient Quality Indicator software. The observed/expected ratio and outlier status based on stroke types across hospitals were examined using Pearson correlation coefficients (r) and weighted κ. RESULTS Overall 30-day stroke mortality rates were 15.2% and varied from 11.3% for ischemic stroke and 37.3% for intracerebral hemorrhage. Hospital risk-adjusted ischemic stroke observed/expected ratio was weakly correlated with its own intracerebral hemorrhage observed/expected ratio (r=0.38). When examining hospital performance group (mortality better, worse, or no different than average), disagreement was observed in 35 of 81 hospitals (κ=0.23). Total stroke mortality observed/expected ratio and rankings were correlated with intracerebral hemorrhage (r=0.61 and κ=0.36) and ischemic stroke (r=0.94 and κ=0.71), but many hospitals still switched classification depending on mortality metrics. However, hospitals treating a higher percent of hemorrhagic stroke did not have a statistically significant higher total stroke mortality rate relative to those treating fewer hemorrhagic strokes. CONCLUSIONS Hospital stroke mortality ratings varied considerably depending on whether ischemic, hemorrhagic, or total stroke mortality rates were used. Public reporting of stroke mortality measures should consider providing risk-adjusted outcome on separate stroke types.