Introduction: Computerized Tomography (CT) scans are central to the diagnosis and follow-up of patients with ischemic stroke, yet concerns remain about the overuse of CT scans because of high costs and potential excess radiation risk. There is little or no evidence on differences across regions, hospitals, or race/ethnicity groups with regard to high rates of CT scans, and why they might occur.

Methods: We used all Medicare fee-for-service claims data from 2008 through 2009 for ischemic stroke admissions with follow-up of one year (through 2010). A total of 327,521 patients were admitted for ischemic stroke during this period. The primary outcome variable was receiving 4 or more head CTs in the year following admission (defined as increased CT utilization). Risk adjustment measures included sex, race/ethnicity, comorbidities on admission, and hierarchical condition categories (HCCs).

Results: The average number of head CTs in the year after admission for stroke was 1.94, whereas 11.9% of the patients had 4 or more. Regionally, risk-adjusted rates of increased CT utilization ranged from 4.1% in Grand Junction, CO to 20.0% in East Long Island, NY. Average risk-adjusted rates of increased CT utilization were 2.6% higher for Black patients than for white patients (95% C.I., 2.1% to 3.1%), but there was considerable variation across regions, with Dearborn MI experiencing much greater increased CT utilization rates for Black stroke patients (30.1%, compared to 14.3% for whites) and Columbus, GA experiencing much lower rates (9.3% for Black patients compared to 17.2% for whites). One important explanatory factor was fragmentation of care, as measured by the number of different doctors seen; patients living in the top quintile regions (in regards to fragmentation of care) experienced a 5.9% (95% C.I., 5.5 to 6.3%) higher rate of increased CT utilization; the corresponding odds ratio was 1.77 (95% C.I., 1.71 to 1.83).

Conclusions: There is little consensus on the “right” number of CT scans for ischemic stroke patients reflected in wide practice patterns for similar patients or for Black patients versus white patients. Fragmentation of care is likely to lead to too many CTs, with a consequent adverse impact on radiation exposure.

Patient Care: It will assist with health science research by identifying areas of inefficient healthcare delivery at the hospital referral region level. Increased utilization did not correlate with improved outcomes, but paralleled spending in corresponding HRRs. In investigating this, we demonstrated that fragmentation of care could explain the racial and geographic disparities to some degree. In fact, increased fragmentation was associated with increased utilization of head CTs. Regions of particularly fragmented care were identified. Targeting of these regions and providing more consistent care could potentially minimize this phenomenon. Fragmentation of the current post-stroke chain of care could benefit from the introduction of case managers or "navigators," discharge planning, electronic medical records, and evidence-based neuro-rehabilitation guidelines.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the significant geographic variation in CT utilization for acute ischemic stroke was observed throughout the United States, and identify particular outliers 2) Describe the prominent racial disparities in the rate of head CTs in acute ischemic stroke patients 3) Identify areas of significant fragmentation of care and their correlation with CT utilization

References: 1. Fisher ES, McClellan MB, Safran DG. Building the path to accountable care. N Engl J Med 2011;365:2445-7. 2. Schwamm LH, Reeves MJ, Pan W, et al. Race/ethnicity, quality of care, and outcomes in ischemic stroke. Circulation 2010;121:1492-501. 3. Xian Y, Holloway RG, Noyes K, Shah MN, Friedman B. Racial differences in mortality among patients with acute ischemic stroke: an observational study. Ann Intern Med 2011;154:152-9. 4. Fonarow GC, Smith EE, Reeves MJ, et al. Hospital-level variation in mortality and rehospitalization for medicare beneficiaries with acute ischemic stroke. Stroke 2011;42:159-66. 5. Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84. 6. The Dartmouth atlas of health care. The Dartmouth Atlas Project. Lebanon, NH; 2010. 7. O'Toole LJJ, Slade CP, Brewer GA, Gase LN. Barriers and facilitators to implementing primary stroke center policy in the United States: results from 4 case study states. Am J Public Health 2011;101:561-6. 8. Wissel J, Olver J, Sunnerhagen KS. Navigating the poststroke continuum of care. J Stroke Cerebrovascular Dis 2013;22:1-8. 9. Martin AB, Lassman D, Washington B, Catlin A, National Health Expenditure Accounts Team. Growth in US health spending remained slow in 2010; health share of gross domestic product was unchanged from 2009. Health Aff(Millwood) 2012;31:208-19.