Which Hospitals Treat Patients with the Most Severe Acute Ischemic Strokes? Implications for Hospital Mortality Reporting

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1 Which Hospitals Treat Patients with the Most Severe Acute Ischemic Strokes? Implications for Hospital Mortality Reporting Risk adjustment is critical for assessing outcomes and reporting clinical outcomes at the hospital level. CMS has expressed interest in reporting hospital s risk standardized 30-day mortality rates for patients with acute ischemic stroke. In a previously published GWTG-Stroke study utilizing Medicare Fee for service data linked to registry data it was demonstrated that adjustment for stroke severity was essential for hospital ranking for acute ischemic stroke. Despite this published evidence regarding the importance for adjusting for stroke severity in acute ischemic stroke mortality models and lack of NQF endorsement for the Yale/CMS model, CMS has proposed going forward with public reporting of hospitals 30-day risk-standardized mortality rates without adjustment for stroke severity. This has the potential to adversely impact hospitals that care for acute ischemic stroke patients by mischaracterizing their performance. While it is known that stroke severity can vary by hospital, very little is known regarding the patient and hospital characteristics of those hospitals that treat patients with greater and lesser stroke severity. These data help identify which hospitals are substantially more likely to be misclassified in 30-day risk standardized mortality rates for acute ischemic stroke using models without adjustment for stroke severity. Those hospitals treating patients with significantly greater stroke severity will be more likely to have their performance misclassified as inappropriately high mortality using 30-day risk models that do not adjust for stroke severity. Analysis summary This study reports on a recent cohort of patients with acute ischemic stroke admitted to participating GWTG-Stroke hospitals from 200 to 202. There were 35 participating hospitals with 602,34 patients. Stroke severity was documented in 40,66 patients, which reflects 68.0% of all the cases entered. The mean NIHSS was 6.8 and varied substantially by hospital. When hospitals were grouped by quintiles the mean NIHSS were as follows: Quintile Number of Number of Mean NIHSS Range Hospitals Patients NIHSS

2 Patient and hospital characteristics associated with hospital level stroke severity are summarized below. Hospitals treating patients with greater stroke severity were substantially more likely to provide care for patients who were black or Hispanic, or transported by EMS. These hospitals were larger, teaching hospitals, having higher volume of stroke patients, and treated more patients with tpa. Hospitals treating patients with higher stroke severity, as expected, have higher unadjusted in-hospital mortality rates. African-American race and Hispanic ethnicity both are associated with higher hospital level stroke severity. As a result, the nation s safety net hospitals that care for these disadvantaged groups are most likely to be unfairly penalized by RSMR measures that do not take stroke severity into account, depriving them of needed resources and unduly causing concerns in these communities of substandard care. As patients transported by EMS have greater stroke severity, hospitals which participate in stroke systems of care with EMS diversion are also most likely to be unfairly penalized by RSMR that do not take stroke severity into account, providing perverse incentives to discourage hospitals from participating in stroke systems of care. There were however little differences in the demographics and comorbid conditions that are used in CMS risk adjustment models among hospitals treating patients with greater or lesser stroke severity, suggesting that the hospital level variation in case mix could not be captured by current comorbidity codes and requires a direct measure of stroke severity. Variable Level Q (mean NIHSS.3-5.5) (N=8535) Demographics (N=206) NIHSS 6.3-.) (N=36).-8) (N=3253) 8-3.3) (N=2400) Age (8-0 ), year* Gender [D] Ethnicity/Race [D] Median < th th Mean STD Female < Male Missing UTD <.000 Native Hawaiian or Pacific Islander White Asian American Indian or Alaska

3 Variable Level Q (mean NIHSS.3-5.5) (N=8535) Native Black or African (N=206) NIHSS 6.3-.) (N=36) ) (N=3253) 8-3.3) (N=2400) American Hispanic Missing Race (Derived) Other <.000 Hispanic AA NH White Arrival and Admission Information Arrival:OFF hrs:not am- 6pm,Sat, Sun Patient Arrival Yes < No Missing ND/Unknown <.000 Private EMS Missing EMS Arrival Yes No Missing < LKW to Arrival, min* Median < th th Mean STD Max Missing(%) Medical History Atrial Fib/Flutter Yes 40.3 No CAD/prior MI Yes No <

4 Variable Level Q (mean NIHSS.3-5.5) (N=8535) Carotid Stenosis No (N=206) NIHSS 6.3-.) (N=36).-8) (N=3253) 8-3.3) (N=2400) Yes < Diabetes Mellitus Yes No Dyslipidemia Yes No < Hypertension Yes No Prosthetic heart valve PVD Yes No Yes <.000 No Heart Failure Yes No Smoker Yes No < Previous Stroke/TIA Yes No Diagnosis & Evaluation First NIH Stroke Scale total score recorded by hospital personnel* Median < th th Mean STD Max Missing(%)

5 Variable Level Q (mean NIHSS.3-5.5) (N=8535) NIHSS levels* (N=206) NIHSS 6.3-.) (N=36).-8) (N=3253) 8-3.3) (N=2400) < Missing Measurements BMI (Kg/m2)* SBP ( mmhg)* Heart Rate ( bmp)* Serum Creatinine (0-20 mg/dl)* Blood Glucose ( mg/dl)* Median th th Mean STD Min Max Missing(%) Median th th Mean STD Min Max Missing(%) Median < th th Mean STD Min Max Missing(%) Median th th Mean STD Max Missing(%) Median < th th Mean STD Min Max Missing(%)

6 Variable Level Q (mean NIHSS.3-5.5) (N=8535) (N=206) NIHSS 6.3-.) (N=36).-8) (N=3253) 8-3.3) (N=2400) INR (0-25)* Median < th th Mean STD Max Missing(%) In-Hospital Outcomes In-hospital Mortality (Transfers Out excluded) Yes <.000 No Variable Level Q (mean NIHSS.3-5.5) (N=20) Hospital Characteristics (N=20) NIHSS 6.3-.) (N=2) Q4 (mean NIHSS.-8) (N=2) 8-3.3) (N=26) + Number of Beds* Region Academic Hospital JCC Primary Stroke Center Location: Rural (vs. Urban) Avg. Annual Ischemic cases* Median < th th Mean STD Min Max Missing(%) West <.000 South Midwest Northeast Yes <.000 No Missing Yes No Yes No Median < th th Mean STD

7 Variable Level Q (mean NIHSS.3-5.5) (N=20) (N=20) NIHSS 6.3-.) (N=2) Q4 (mean NIHSS.-8) (N=2) 8-3.3) (N=26) Min Max Missing(%) Avg. Annual Ischemic cases Avg. Annual TPA cases* Avg. Annual TPA cases > <.000 > Median < th th Mean STD Max Missing(%) > <.000 >