Comprehensive Stroke Centers Overcome the Weekend Versus Weekday Gap in Stroke Treatment and Mortality

James S. McKinney, MD; Yingzi Deng, MD, MS; Scott E. Kasner, MD, MSCE; John B. Kostis, MD; for the Myocardial Infarction Data Acquisition System (MIDAS 15) Study Group

Background and Purpose— staffing may be reduced on weekends. Prior studies of weekend disparities in stroke care have focused on in-hospital mortality with variable results. We hypothesized that 90-day mortality was higher in patients with stroke hospitalized on weekends versus weekdays, and this difference has been minimized over time by improvements in organization and delivery of stroke care. Methods—We used the Myocardial Infarction Data Acquisition System administrative database, which includes data on patients discharged with a primary diagnosis of cerebral infarction from all nonfederal in New Jersey between 1996 and 2007. Out-of-hospital deaths were assessed by matching MIDAS records with New Jersey death registration files. New Jersey hospitals are designated by the state as comprehensive stroke centers, primary stroke centers, or nonstroke centers. The primary outcome measure was 90-day all-cause mortality after hospital admission. Results—A total of 134 441 patients were admitted with a primary diagnosis of cerebral infarction during the study period. A total of 23.4% were admitted to a comprehensive stroke center, 51.5% to a primary stroke center, and 25.1% to a nonstroke center. Ninety-day mortality was greater in patients with stroke admitted on weekends compared with weekdays (17.2% versus 16.5%; Pϭ0.002). The adjusted risk of death at 90 days was significantly greater for weekend admission (hazard ratio, 1.05; 95% CI, 1.02 to 1.09). No difference in 90-day mortality was observed for patients admitted to comprehensive stroke centers on weekends versus weekdays (hazard ratio, 1.01; 95% CI, 0.95 to 1.08). Conclusions—Patients with stroke admitted on weekends to New Jersey hospitals had a significantly higher risk of death by 90 days. No such difference in mortality was observed at comprehensive stroke centers. (Stroke. 2011;42:2403-2409.) Key Words: ischemic stroke Ⅲ stroke center Ⅲ thrombolysis Ⅲ weekend

isparities in care and clinical outcomes of patients exist hospital mortality between weekend and weekday admissions Dbetween those hospitalized on weekends versus week- for 599 087 patients with stroke from 2002 to 2007.8 Further- days. Hospital staffing may be reduced in quantity and more, no difference in in-hospital mortality has been ob- spectrum on weekends. This disparity has been shown to served in patients admitted to comprehensive stroke centers adversely affect treatment and outcomes in patients with on weekends.6 There are little data on longer-term outcomes myocardial infarctions.1 There have been inconsistent find- of patients with stroke admitted to hospitals on the weekend ings in patients admitted with stroke with most studies versus weekday. reporting early mortality.2–9 Canadian and Japanese studies In 2004, the State of New Jersey enacted the “Stroke Center have shown an increased risk of death and functional disabil- Act,” which required the NJ Department of Health and Senior ity at 7 days with weekend stroke admission.2,3,9 In-hospital Services (DHSS) to designate hospitals that meet certain stan- mortality was increased in patients admitted on “off-hours” in dards as primary stroke centers (PSCs) or comprehensive stroke the Get With The Guidelines–Stroke database (OR, 1.09; centers (CSCs). The NJ DHSS began receiving applications 95% CI, 1.03 to 1.14).4 A report of stroke mortality in and issued its first certification for both PSC and CSC in Sweden over 4 decades showed an increased risk of death 2007. Further details are available through the NJ DHSS web with weekend admission, but the authors noted that this effect site (www.state.nj.us/health/healthfacilities/documents/ac/ diminished over time.5 Temporal improvements in stroke care njac43g_hoslicstd.pdf). may account for this trend. A study using the Nationwide The aims of this study are 2-fold: (1) to compare 90-day Inpatient Sample Database reported no difference in in- mortality rates among patients admitted with acute ischemic

Received December 23, 2010; final revision received March 4, 2011; accepted March 7, 2011. From The Cardiovascular Institute of New Jersey and the Departments of Neurology (J.S.M.) and (Y.D., J.B.K.), University of Medicine and of New Jersey–Robert Wood Johnson , New Brunswick, NJ; and the Department of Neurology (S.E.K.), University of Pennsylvania School of Medicine, Philadelphia, PA. The online-only Data Supplement is available at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.110.612317/-/DC1. Correspondence to James S. McKinney, MD, Department of Neurology, UMDNJ–Robert Wood Johnson Medical School, 125 Paterson Street, New Brunswick, NJ 08901. E-mail [email protected] © 2011 American Heart Association, Inc. Stroke is available at http://stroke.ahajournals.org DOI: 10.1161/STROKEAHA.110.612317 2403 2404 Stroke September 2011 stroke on weekends and those admitted on weekdays; and (2) Table 1. Patient Demographics and Clinical Characteristics to determine whether any differences in mortality could be Weekend Weekday explained by temporal improvements in stroke care or stroke (Nϭ37 321) (Nϭ97 120) P* center designation. Age, y (meanϮSD) 73.5 Ϯ 13.3 73.4 Ϯ 13.4 0.20 Methods Gender: female 20 629 (55.3%) 53 068 (54.6%) 0.04 We used information from the Myocardial Infarction Data Acquisi- Race 0.03 1,10–12 tion System (MIDAS) administrative database for this study. White 28 505 (76.4%) 73 995 (76.2%) MIDAS contains demographic and clinical data on patients dis- charged with a primary diagnosis of cerebral infarction (codes Black 5651 (15.1%) 15 175 (15.6%) 433.01, 433.11, 433.21, 433.31, 433.81, 433.91, 434.01, 434.11, and Other 3165 (8.5%) 7950 (8.2%) 434.91 of the International Classification of Diseases, 9th Revision, Payer 0.30 Clinical Modification) from all nonfederal acute care hospitals in New Jersey. The database also includes records of treatment with Commercial 4547 (12.2%) 11 894 (12.3%) intravenous (IV) thrombolysis after 1998 (International Classifica- Medicare 25 247 (67.7%) 65 934 (67.9%) tion of Diseases, 9th Revision code 99.10). Data for the following Medicaid 846 (2.3%) 2278 (2.4%) coexisting conditions were available: hypertension, diabetes, atrial fibrillation, and chronic renal disease. We obtained data on out-of- Self-pay 1485 (4.0%) 3611 (3.7%) hospital deaths by matching MIDAS records with NJ death registra- HMO 5195 (13.9%) 13 401 (13.8%) tion files using previously validated linkage and consolidation Comorbid conditions software (The Link King).13 Out-of-state deaths were not recorded. Outcomes were assessed by a blinded automated procedure. Hypertension 25 656 (68.7%) 67 044 (69.0%) 0.30 Diabetes 10 859 (29.1%) 28 459 (29.3%) 0.50 Study Population Atrial fibrillation 8015 (21.5%) 20 422 (21.0%) 0.03 MIDAS included 134 441 patients admitted between 1996 and 2007 Renal disease 1759 (4.7%) 4875 (5.0%) 0.02 with cerebral infarction as the primary reason for admission. Only the first discharge record for a patient was included. Subsequent Congestive heart 4824 (12.9%) 12 367 (12.7%) 0.30 records were excluded to avoid duplicating data or introducing bias failure from interhospital transfers or readmission for the same event. Admission source Ͻ0.0001 Patients who were admitted to federal hospitals or homes or Emergency 33 358 (89.4%) 81 923 (84.4%) had a stroke during an admission for another diagnosis or procedure department were excluded. referral 1972 (5.3%) 9639 (9.9%) Study Variables Transfer 1175 (3.2%) 3352 (3.5%) The primary outcome variable was all-cause mortality within 90 days Other 816 (2.2%) 2206 (2.3%) of hospital admission. In-hospital and cumulative (inpatient and postdischarge) death rates at 30, 90, and 365 days were also Stroke center 0.0009 examined. The primary independent variable was admission on designation weekends (Saturday, Sunday, and holidays) versus weekdays. Covari- CSC 8952 (24.0%) 22 465 (23.1%) ates included patient demographics, coexisting conditions, and treatment PSC 19 314 (51.8%) 49 961 (51.4%) with IV thrombolysis. Measures of stroke severity were not available. Each hospital in MIDAS was categorized based on its current NJ DHSS NSC 9055 (24.3%) 24 691 (25.4%) designation as CSC, PSC, or as a nonstroke center (NSC). Procedures IV tPA 605 (1.6%) 1299 (1.3%) Ͻ0.0001 Statistical Analysis Cerebral 2780 (7.5%) 7085 (7.3%) 0.30 We examined how differences in mortality between weekend and arteriography weekday admissions have changed over time. Data for the period from 1996 to 2007 were grouped into 2-year intervals. We Carotid 316 (0.9%) 1074 (1.1%) Ͻ0.0001 compared weekend and weekday admissions in terms of both endarterectomy in-hospital and cumulative all-cause mortality. To adjust for Length of stay 8.4 Ϯ 11.8 8.4 Ϯ 10.1 0.30 confounders, we used Cox proportional hazard models in comparing (meanϮSD) the risk of death associated with weekend versus weekday admissions at 90 days. Multivariable logistic regression models were used to compare HMO indicates health maintenance organization; CSC, comprehensive stroke treatment among hospital types accounting for the measurable con- center; PSC, primary stroke center; NSC, nonstroke center; IV tPA, intravenous founding effects of patient demographics and coexisting conditions. tissue-type plasminogen activator; SD, standard deviation. ␹2 Statistical significance was defined as a probability value Յ0.01. *P values are based on tests for categorical variables and t tests for We examined whether the difference in mortality between week- continuous variables. end and weekday admissions could be explained by differences in stroke care temporally by year of admission or operationally by stroke center certification. Year of admission or stroke center Results certification would be considered to mediate the association between weekend and weekday admission and mortality if the hazard ratio Patient Characteristics decreased when included in the hazard model. There were 134 441 patients admitted between 1996 and Statistical analyses were performed using SAS software. 2007 with a primary diagnosis of cerebral infarction with The Institutional Review Boards of the NJ DHSS and the 27.8% admitted on weekends. Baseline patient demograph- University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School approved the study. Informed ics were similar (Table 1). There was a 27.9% decline in consent was not required. stroke admissions over the study period; however, the ratio McKinney et al CSCs Overcome Weekend vs Weekday Gap 2405

Figure 1. Weekend versus weekday stroke admission and mortality.

of weekend to weekday admissions remained unchanged began designating stroke centers, compared with 1996 and (Figure 1). 1997 (HR, 0.86; 95% CI, 0.82 to 0.91). Additionally, we examined potential effects that PSC Hospital Characteristics designation by The Joint Commission may have had by Eighty-eight hospitals were represented in this analysis; 12 analyzing mortality before and after 2003, when The Joint were CSC, 43 were PSC, and 33 were NSC. Of the total Commission stroke center accreditation began. Adjusted population, 23.4% (31 417) were admitted to a CSC, 51.5% 90-day mortality remained higher for patients admitted on (69 275) to a PSC, and 25.1% (33 746) to a NSC. Patients weekends between 1996 and 2002 (HR, 1.05; 95% CI, 1.01 to with stroke were significantly more likely to be admitted to a 1.09) and 2003 and 2007 (HR, 1.05; 95% CI, 1.00 to 1.11). CSC on weekends (Table 1). Patients with stroke were more likely to be admitted to the hospital through the on the weekend than weekday (89.4% versus 84.4%, PϽ0.0001). There was a corresponding significant Table 3. Adjusted Risk of Death 90 Days After decline in admissions via physician referral on weekends Stroke Admission Ͻ versus weekdays (5.3% versus 9.9%, P 0.0001). Effect Hazard Ratio (95% CI) Mortality Weekend vs weekday admission 1.05 (1.02–1.09) The overall 90-day mortality for patients admitted with Age, y 1.05 (1.05–1.05) cerebral infarction during the study was 16.7% (Table 2). Gender: female 1.02 (0.99–1.05) Mortality 90 days after admission was significantly higher for Race patients admitted on weekends than on weekdays (17.2% Black vs white 0.91 (0.87–0.95) versus 16.5%; Pϭ0.001). In-hospital and 30-day mortality Other vs white 0.84 (0.80–0.89) rates were also increased for patients admitted on weekends; Comorbid conditions however, this difference was diluted 1 year after admission Hypertension 0.64 (0.62–0.65) (Table 2). Ninety-day stroke mortality declined throughout Diabetes 1.02 (0.99–1.05) the study period for both weekend and weekday admissions (Figure 1). After adjusting for available confounding vari- Atrial fibrillation 1.83 (1.77–1.88) ables, 90-day mortality remained significantly higher for Renal disease 2.35 (2.24–2.46) patients admitted on weekends than on weekdays (hazard Year of admission ratio [HR], 1.05; 95% CI, 1.02 to 1.09; Table 3). Mortality 1998–1999 vs 1996–1997 1.03 (0.98–1.07) was higher for patients admitted on weekends than weekdays 2000–2001 vs 1996–1997 1.04 (1.00–1.09) for all time periods (Figure 1). However, the adjusted risk of 2002–2003 vs 1996–1997 1.08 (1.03–1.13) death at 90 days was significantly lower for patients admitted 2004–2005 vs 1996–1997 1.01 (0.96–1.05) between 2006 and 2007, the time period when New Jersey 2006–2007 vs 1996–1997 0.86 (0.82–0.91) Admission source: emergency department vs other 0.93 (0.90–0.97) Table 2. All-Cause Mortality After Stroke Admission IV tPA 1.45 (1.31–1.62) Total Weekend Weekday Certified stroke center vs NSC 0.95 (0.92–0.99) ϭ ϭ ϭ (N 134 441) (N 37 321) (N 97 120) P* Hospital stroke case volume In-hospital 11 598 (8.6%) 3357 (9.0%) 8241 (8.5%) 0.003 Second vs first quartile 1.06 (1.00–1.11) Ͻ 30 d 15 657 (11.7%) 4572 (12.3%) 11 085 (11.4%) 0.0001 Third vs first quartile 1.04 (0.98–1.09) 90 d 22 412 (16.7%) 6415 (17.2%) 15 997 (16.5%) 0.002 Fourth vs first quartile 1.08 (1.02–1.14) 1 y 32 411 (24.1%) 9440 (25.3%) 24 134 (24.9%) 0.09 IV indicates intravenous; tPA, tissue-type plasminogen activator; NSC, *P values are based on ␹2 tests. nonstroke centers; CI, confidence interval. 2406 Stroke September 2011

Table 4. Adjusted Odds of Receiving Intravenous PϽ0.0001). No increase in adjusted 90-day mortality was Thrombolysis During Stroke Admission observed in patients admitted to CSC on weekends (HR, 1.01; Effect OR (95% CI) 95% CI, 0.95 to 1.08). However, adjusted 90-day mortality was significantly greater with weekend admission to PSCs Weekend admission 1.19 (1.07–1.31) (HR, 1.06; 95% CI, 1.02 to 1.10) and NSCs (HR, 1.08; 95% Year of admission CI, 1.02 to 1.15). The odds of in-hospital death by stroke 2000–2001 vs 1998–1999* 3.16 (2.48–4.03) center designation were similar: CSC (OR, 1.00; 95% CI, 2002–2003 vs 1998–1999* 3.95 (3.11–5.01) 0.92 to 1.09), PSC (OR, 1.07; 95% CI, 1.00 to 1.13), and NSC 2004–2005 vs 1998–1999* 5.80 (4.61–7.31) (OR, 1.10; 95% CI, 1.01 to 1.20). Trends in stroke center 2006–2007 vs 1998–1999* 9.86 (7.88–12.33) admission rates, IV thrombolysis, and 90-day mortality are Age, y 0.98 (0.97–0.98) presented in Figure 2. IV thrombolysis rates by stroke center Gender: female 0.82 (0.74–0.90) designation are presented in Supplemental Table I (http://stroke.ahajournals.org). Race Black vs white 0.85 (0.74–0.98) Discussion Other vs white 1.11 (0.95–1.29) There may be disparities in hospital care on weekends when Comorbid conditions hospital staffing is reduced. Weekend admission for myocar- Hypertension 0.99 (0.90–1.10) dial infarction is associated with a higher mortality and lower Diabetes 0.64 (0.57–0.72) use of invasive cardiac procedures.1 This disparity has been Atrial fibrillation 1.98 (1.78–2.20) termed the “.” Previous reports examining the weekend effect in stroke care have reported variable results Renal disease 0.74 (0.60–0.91) with most studies focusing on in-hospital mortality.2–5,7–9 Our Stroke center analysis of the MIDAS database shows that patients with CSC vs NSC 5.82 (4.88–6.94) stroke admitted on weekends have an increased adjusted risk PSC vs NSC 2.48 (2.07–2.96) of death at 90 days compared with those admitted on CSC vs PSC 2.35 (2.13–2.59) weekdays. Admission source: emergency department vs other 1.48 (1.23–1.77) Multiple studies outside of the United States have reported *The comparator time period was 1998–1999 in this analysis. International increased early mortality for patients with stroke admitted on Classification of Diseases, 9th Revision code 99.10 for injection or infusion of weekends. The Canadian Stroke Network found an increase intravenous thrombolytic agent was created in 1998. in 7-day mortality for patients with stroke admitted on CSC indicates comprehensive stroke centers; NSC, nonstroke centers; PSC, weekends (HR, 1.12; 95% CI, 1.00 to 1.25).9 A Taiwanese primary stroke centers; OR, odds ratio; CI, confidence interval. study also reported increased mortality for patients with stroke admitted on weekends.14 However, a German study IV Thrombolysis found no weekend effect on early stroke mortality.15 IV thrombolysis rates were higher for patients with stroke Stroke care organization and delivery may be different in admitted on weekends than weekdays (1.6% versus 1.3%; the United States than abroad. An analysis of the Get With PϽ0.0001). The adjusted odds of treatment with IV tissue- The Guidelines–Stroke Program found a small but significant type plasminogen activator (tPA) remained significantly increase in in-hospital mortality for “off-hours” admission higher for patients admitted on weekends (OR, 1.19; 95% CI, (5.8% versus 5.2%; PϽ0.001).4 This report may underesti- 1.07 to 1.31; Table 4). The adjusted odds of receiving IV tPA mate the overall weekend effect in stroke care because most was also increased at CSCs (OR, 5.82; 95% CI, 4.88 to 6.94) hospitals participating in the Get With The Guidelines–Stroke or PSCs (OR, 2.48; 95% CI, 2.07 to 2.96) compared with Program are CSCs. NSCs. Patients with atrial fibrillation and those admitted A study of stroke care in the United States using the through emergency departments were more likely to receive Nationwide Inpatient Sample Database found no difference in IV tPA; whereas women, blacks, and those with diabetes or in-hospital mortality between weekend and weekday admis- renal disease were less likely to be treated (Table 4). By the sion between 2002 and 2007 (OR, 1.00; 95% CI, 0.972 to time of initial The Joint Commission (2002 to 2003) and NJ 1.029).8 Contrary to this report, our study did show a DHSS (2006 to 2007) stroke center designation, patients were significant increase in in-hospital, 30-day, and 90-day mor- approximately 4 and 10 times more likely to receive IV tPA, tality for patients with stroke admitted on weekends overall respectively, than between 1998 and 1999. and between 2003 and 2007. Differences in study design may account for the differences in observations made by Hoh et al Stroke Center Designation and those in our study. The former study included all Overall, patients with stroke were more likely to be admissions for an ischemic stroke diagnosis, whereas we admitted to CSCs than NSCs on weekends than weekdays limited ours to the first hospitalization with a primary (PϽ0.001). However, weekday versus weekend admis- diagnosis of ischemic stroke. Furthermore, we were able to sions remained similar in all time periods studied for all include holiday admissions in the weekend cohort, whereas hospital types, except from 2006 to 2007, when there was Hoh and colleagues could not. a significant increase in the percentage of patients admitted to Patients admitted on weekends were more likely to receive a CSC on weekends versus weekdays (30.3% versus 26.8%; treatment with IV tPA in this analysis. Although this trend McKinney et al CSCs Overcome Weekend vs Weekday Gap 2407

Figure 2. A, Comprehensive stroke center admissions, mortality, and intravenous thrombolysis rates. B, Primary stroke center admis- sions, mortality, and intravenous thrombolysis rates. C, Nonstroke center admissions, mortality, and intravenous thrombolysis rates. tPA indicates tissue-type plasminogen activator. 2408 Stroke September 2011 was not found in an analysis of thrombolytic use in Europe, functioned as comprehensive centers before the development it is consistent with other previously published reports of of the state designation. Ten of the 12 centers received CSC stroke care in the United States.7,8,16 Previously proposed designation within the first year of review (2007), and our explanations include: decreased traffic volume and work results speak to the existence of superior care at CSC. obligations that may decrease delays in hospital arrival; Interestingly, there was a significant reduction in 90-day risk quicker access to diagnostic imaging and neurological eval- of death (HR, 0.86; 95% CI, 0.82 to 0.91) during the time uation outside of weekday work schedules; and more severe period of NJ state stroke center designation that was not seen strokes on weekends.7,8 An alternative explanation is that in other time periods. This could indicate that the statewide many ’ offices are closed on weekends, forcing designation process had a positive effect on stroke care as a patients to access through emergency medical whole across New Jersey and deserves further study. services and emergency departments thereby reducing delays An additional limitation is the retrospective nature of the in hospital presentation. In our study, there was a 4.6% study, which has potential for selection bias. The recently increase in stroke admission by physician referral during the developed New Jersey Acute Stroke Registry will prospec- week. This difference would account for Ͼ6000 patients who tively collect data on all stroke admissions and allow for had potential delays in stroke diagnosis and treatment be- future studies. cause medical care was not accessed by calling 911 and using Neither of these limitations should detract from the pri- established systems for delivering acute care. Furthermore, mary finding that 90-day mortality was increased with week- emergency medical services may triage patients with sus- end stroke admission. Our data were collected between 1996 pected stroke to stroke centers where they are more likely to and 2007, and it is possible that current stroke care has be treated on weekends. The increase in weekend emergency improved further. This study has several important strengths, department presentation and CSC admission observed in this namely the large sample size that includes all patients study may account for increased rates of weekend IV tPA admitted to a NJ acute care hospital over a 12-year period for administration and deserves further study. In contrast to other a first-time diagnosis of an ischemic stroke, which may states, New Jersey does not have a statute requiring emer- reduce or eliminate selection bias. gency medical services to take patients with suspected stroke The observation that weekend stroke admission indepen- to designated stroke centers. Encouragingly, overall IV tPA dently increases the risk of 90-day death by 5% is both rates increased 10-fold throughout the study period. This significant and clinically meaningful. This increase in mor- marked increase in acute stroke treatment is likely multifac- tality could account for several thousand deaths annually in torial, but undoubtedly ongoing community and healthcare the United States. More appropriate hospital staffing and provider education, stroke center designation by federal and organization of stroke care such as that provided by CSC may state regulatory agencies, and hospital-based quality assur- negate the weekend effect and save lives. ance and performance improvement initiatives are largely responsible. Albright et al reported no difference in 90-day mortality Conclusions In the MIDAS database, 1996 to 2007, patients with stroke between weekend and weekday stroke admission to 2 CSCs and concluded that around the clock availability of stroke admitted on weekends had a significantly higher risk of death specialists, advanced neuroimaging, and specialized nursing by 90 days. No difference in mortality was observed at CSCs. care may account for this difference.6 In our analysis of the MIDAS database, there was no increased risk of 90-day death Sources of Funding with CSC admission on weekends. However, a weekend This study was funded in part by the Robert Wood Johnson Foundation and the Schering-Plough Foundation. effect was present for patients with stroke admitted to PSCs or NSCs. We do not feel that this simply reflects hospital Disclosures volume. In the multivariable model, admission to the highest None. volume centers was associated with an increase in risk of death, whereas CSC designation was associated with lower References mortality. In New York State, patients admitted to designated 1. Kostis WJ, Demissie K, Marcella SW, Shao YH, Wilson AC, Moreyra stroke centers have a significant reduction in 30-day mortality AE. Weekend versus weekday admission and mortality from myocardial compared with patients admitted to NSCs even after adjusting infarction. N Engl J Med. 2007;356:1099–1109. 2. Saposnik G, Baibergenova A, Bayer N, Hachinski V. Weekends: a dan- for hospital volume.17 gerous time for having a stroke? Stroke. 2007;38:1211–1215. 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It is possible that these centers did author reply e95. 6. Albright KC, Raman R, Ernstrom K, Hallevi H, Martin-Schild S, Meyer not provide CSC-level care during the study period. How- BC, et al. Can comprehensive stroke centers erase the ‘weekend effect’? ever, we feel that the majority of CSCs in New Jersey Cerebrovasc Dis. 2009;27:107–113. McKinney et al CSCs Overcome Weekend vs Weekday Gap 2409

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