Clinical Outcomes after Thrombectomy for Acute Ischemic Stroke on Weekends versus Weekdays Ali Saad, MD,* Malik Muhammad Adil, MD,† Vikas Patel, MD,* Kumiko Owada, MD,* Melanie J. Winningham, MD,* and Fadi Nahab, MD*

Background: The objective of this study was to determine whether clinical outcomes differed in acute ischemic stroke (AIS) patients who underwent thrombectomy on weekends versus weekdays. Methods: Patients with a primary diagnosis of AIS who underwent thrombectomy were identified from the Nationwide Inpatient Sample from 2005 to 2011 and stratified according to weekend or weekday admission. Logistic regression analysis was performed to identify factors associated with moderate-to-severe disability at hospital discharge in teaching and nonteaching hospitals. Results: Of 12,055 patients with AIS who underwent thrombectomy during the study period, 2862 (23.7%) were admitted on a weekend. In a multivariate logistic regression analysis, factors associated with moderate or severe disability at discharge in nonteaching hospitals were weekend admission (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.8; P 5 .04), diagnosis of hypertension (OR, 1.9; 95% CI, 1.0-3.6; P 5 .05), and Medicare or Medicaid insurance status (OR, 2.1; 95% CI 1.14.3; P 5 .02); factors associated with moderate or severe disability at discharge in teaching hospitals were age .70 years (OR, 1.5; 95% CI, 1.1-2.2; P 5 .02), pneumonia (OR, 4.7; 95% CI, 2.2-10.2; P , .0001), sepsis (OR, 8.2; 95% CI, 1.2-54.8; P 5 .03), intracranial hemorrhage (OR, 3.3; 95% CI, 1.8-6.1; P 5 .0001), and treatment in a Northwest hospital region (OR, 1.7; 95% CI, 1.2-2.4; P 5 .03). Conclusions: AIS patients undergoing thrombectomy who were admitted to nonteaching hospitals on weekends were more likely to be discharged with moderate-to-severe disability than those admitted on weekdays. No weekend effect on discharge clinical outcome was seen in teaching hospitals. Key Words: All cerebrovascular disease/stroke—harm/risk analysis—infarction—weekend effect—thrombectomy—endovascular therapy. Ó 2014 by National Stroke Association

Introduction Prior studies have demonstrated differences in the quality of care and clinical outcomes in stroke patients

From the *Department of Neurology, Emory University, Atlanta, Georgia; and †Department of Internal Medicine and Neurology, and Ochsner Neuroscience Institute, Ochsner Clinic Foundation, New Orleans, LA. Received February 17, 2014; revision received April 7, 2014; accepted June 15, 2014. Statistical analysis was completed by Malik Muhammad Adil. Address correspondence to Ali Saad, MD, Department of Neurology, Emory University, 180 Waterman Ave, Apt 430, North Providence, RI 02911. E-mail: [email protected]. 1052-3057/$ - see front matter Ó 2014 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.06.006

2708

admitted on weekends versus weekdays. In the United States, studies have found a ‘‘weekend effect’’ associated with significant increases in mortality in the first week and the first 90 days after stroke.1-4 Other US studies have found an increase in frequency of thrombolytic use in patients presenting on the weekend with no difference in mortality or discharge disposition compared with weekday presentation.5 In a United Kingdom study, patients presenting on the weekend were less likely to receive thrombolysis than on a weekday; however, studies from Germany and Taiwan found an increased frequency of thrombolytic use in patients presenting on a weekend.6-9 There has been limited data evaluating the weekend effect on outcomes among patients who have undergone thrombectomy in the treatment of acute ischemic stroke

Journal of Stroke and Cerebrovascular Diseases, Vol. 23, No. 10 (November-December), 2014: pp 2708-2713

OUTCOMES AFTER THROMBECTOMY FOR AIS

(AIS). Given the importance of time to reperfusion on clinical outcomes, we hypothesized that a weekend effect may be seen in clinical outcomes at discharge in AIS patients undergoing thrombectomy.

Methods Data from the National Inpatient Sample (NIS) from 2005 to 2011 were used for this analysis. A comprehensive synopsis on NIS data is available at http://www.hcup-us. ahrq.gov. We used the International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) primary diagnosis codes 433-434 to identify patients admitted with ischemic stroke. We also used ICD-9-CM procedure codes to identify mechanical thrombectomy (39.74 and Medicare severity diagnosis-related group code 543) and cerebral angiography (88.41). Any patient who had an ICD-9 code of mechanical thrombectomy and subsequent code of cerebral angiography was selected as a patient who received thrombectomy. Patients were categorized as having been admitted on weekends (Saturday or Sunday) versus weekdays (Monday through Friday), a distinct variable in the NIS database that is, calculated from the original admission date. The NIS database does not allow identification of specific admission hours. Patients with missing data regarding the day of admission were excluded.

Study Variables The analysis included age, sex, race/ethnicity, and comorbidities obtained from the Agency for Healthcare Research and Quality comorbidity data files including congestive heart failure, diabetes mellitus, hypertension, alcohol abuse, renal failure, and chronic lung disease. We used ICD-9-CM secondary diagnosis codes to identify comorbid atrial fibrillation (427.30 and 427.31), dyslipidemia (272.0-272.9), nicotine dependence (305.1), and stroke-associated complications such as pneumonia (486, 481, 482.8, and 482.3), urinary tract infection (599.0, 590.9), sepsis (995.91, 996.64, 038, 995.92, and 999.3), deep venous thrombosis (451.1, 451.2, 451.81, 451.9, 453.1, 453.2, 453.8, and 453.9), pulmonary embolism (415.1), myocardial infarction (410.0-410.9), and intracerebral hemorrhage (431-432). We also used ICD-9-CM procedure codes to determine the frequency of stroke patients who underwent tracheostomy (31.10, 31.20, 31.21, or 31.29), mechanical ventilation (9672), transfusion (99.04), carotid angioplasty/stent placement (00.63/ 00.64), carotid endarterectomy (38.12), intubation (96.04), gastrostomy (431.1-431.9), and thrombolytic administration (99.10). Severity of patient illness was defined using the All Patient Refined Diagnosis Related Groups, which determines severity of illness based on the extent of physiologic decompensation or organ system loss of function.

2709

The data elements used by the All Patient Refined Diagnosis Related Groups are based on primary and secondary ICD-9-CM diagnoses codes, procedures codes, age, sex, and discharge disposition. These data elements were combined on a patient-specific basis to determine a patient’s severity of illness. The admitting hospitals were classified as teaching or nonteaching and were further characterized into small, medium, and large size based on available hospital beds. Teaching hospitals were defined as those which have an American Medical Association–approved residency program or have membership in the Council of Teaching Hospitals. A teaching hospital was defined as one that meets at least one of the following 3 criteria: residency training approval by the Accreditation Council for Graduate Medical Education, membership in the Council of Teaching Hospitals, and a ratio of full-time equivalent interns and residents to beds of .25 or higher.10 Small-, medium-, and large-sized categories were based on hospital beds, and thresholds for stratification were based on hospital location and teaching status. For example, the definition of large size may vary from exceeding 325 to exceeding 450 acute hospital beds depending on the location and characteristics of the hospital. Other hospital factors evaluated were geographic region in the United States (Northeast, Midwest, West, and South), length of stay, and hospital charges.

Study End Points We included neurologic complication, cardiac complication, postoperative mortality, and a composite end point. Neurologic complications were identified by specific ICD-9-CM code (997.00-997.09), which includes iatrogenic cerebral ischemic complication or intracranial hemorrhage. We also used ICD-9-CM diagnostic codes for the identification of cardiac complications (997.10), which include cardiac arrest, insufficiency, or failure during or as a result of a procedure. The composite end point was defined as any patient who had a neurologic complication, cardiac complication, or postoperative mortality. Discharge status was categorized into routine, home health care, short-term hospital, other facility including intermediate care and skilled nursing home, or death in the NIS. We categorized routine discharge as none to minimal disability and all other discharge status as moderate to severe disability as previously described.11

Statistical Analysis The SAS 9.3 software (SAS Institute, Cary, NC) was used to convert NIS database data into weighted counts to generate national estimates following Healthcare Cost and Utilization Project recommendations. We performed chi-square for categorical and t test for continuous variables to identify differences in study variables and end

A. SAAD ET AL.

2710

Table 1. Patient demographic and clinical characteristics, in-hospital procedures, hospital characteristics, and discharge outcomes of acute ischemic stroke patients who underwent thrombectomy P value

Characteristics

Weekdays

Weekends

Overall number Age, mean 6 SD Women, n (%) Race, n (%) White Black Hispanic Other Comorbid conditions, n (%) Hypertension Diabetes mellitus Dyslipidemia Atrial fibrillation Congestive heart failure Chronic lung disease Renal failure Alcohol abuse Nicotine dependence In-hospital complications, n (%) Pneumonia Deep venous thrombosis Urinary tract infection Sepsis Pulmonary embolism Myocardial infarction Intracranial hemorrhages In-hospital procedure, n (%) Thrombolysis Carotid artery stent placement Carotid endarterectomy Gastrostomy Tracheostomy Mechanical ventilation Intubation Transfusion Hospital bed size, n (%) Small Medium Large APRDRG severity, n (%) None-to-minor loss of function Moderate loss of function Major loss of function Extreme loss of function Hospital regions, n (%) Northeast Midwest South West Hospital teaching status, n (%) Nonteaching Teaching Length of stay, mean 6 SD Hospital charges, mean 6 SD

9193 65 6 35 4594 (50.0)

2862 64 6 34 1372 (48.0)

5356 (72.4) 859 (8.4) 620 (8.4) 560 (7.6)

1673 (74.6) 203 (9.1) 226 (10.1) 138 (6.2)

0.2

6533 (71.1) 1885 (20.5) 617 (6.7) 3634 (39.5) 1613 (17.5) 1232 (13.4) 729 (7.9) 368 (4.0) 1291 (14.0)

1928 (67.4) 2278 (79.6) 163 (5.7) 989 (34.6) 423 (14.8) 366 (12.8) 181 (6.3) 174 (6.0) 462 (16.1)

.07 0.9 0.3 .05 .07 0.6 0.2 .08 0.2

653 (7.1) 207 (2.2) 1603 (17.4) 265 (2.9) 108 (1.1) 55 (.6) 1089 (11.8)

165 (5.8) 53 (1.8) 477 (16.6) 70 (2.5) 65 (2.3) 4.8 (.2) 412 (14.4)

0.2 0.5 0.6 0.5 .08 0.1 0.2

4791 (52.1) 599 (6.5) 74 (.8) 1318 (14.3) 40 (.4) 1269 (13.8) 2413 (26.2) 572 (6.2)

1518 (53.0) 160 (5.6) 10 (.4) 357 (12.4) 0 (.0) 391 (13.6) 781 (27.3) 153 (5.3)

0.6 0.4 0.1 0.2

281 (3.1) 1105 (12.0) 7807 (84.9)

137 (4.8) 279 (9.7) 2446 (85.4)

0.1

82 (.8) 343 (3.7) 5431 (59.1) 3336 (36.3)

15 (.5) 101 (3.5) 1654 (57.8) 1093 (38.2)

0.6

1874 (20.4) 2592 (28.2) 2180 (23.7) 2547 (27.7)

577 (20.2) 843 (29.4) 610 (21.3) 832 (29.1)

0.5

1291 (14.0) 7902 (86.0) 10 6 21 $152,043 6 254,293

393 (13.7) 2469 (86.2) 9 6 19 $155,698 6 295,377

0.8

0.2 0.4

0.9 0.6 0.4

0.4 ,.0001 (Continued )

OUTCOMES AFTER THROMBECTOMY FOR AIS

2711

Table 1. (Continued ) Characteristics Discharge disposition, n (%) None-to-minimal disability Moderate-to-severe disability Outcomes, n (%) Neurologic complications Cardiac complications In-hospital mortality Composite end point

P value

Weekdays

Weekends

1780 (19.3) 5524 (60.0)

530 (18.5) 1757 (61.4)

0.6 0.5

426 (4.6) 54 (.6) 1889 (20.5) 2197 (23.9)

160 (5.6) 5 (.2) 575 (20.1) 697 (24.4)

0.3 0.1 0.8 0.8

Abbreviations: APRDRG, All Patient Refined Diagnosis Related Group; SD, standard deviation.

points between 2 groups (weekend versus weekday admission). A logistic regression analysis was also used to identify the association between hospital characteristics and odds of moderate-to-severe disability in patients who underwent thrombectomy in teaching and nonteaching hospitals separately. All variables that were significant in the univariate analysis were added as ‘‘predictor variables’’ to a step-wise logistic regression model. These variables were retained in the final model if P value was less than .1. A P value less than .05 was considered significant.

Results Of the 12,055 patients with AIS who underwent thrombectomy, 2862 (23.7%) patients were admitted on a weekend. Age, sex, race, and comorbid conditions were similar between patients admitted on weekend versus weekday except for atrial fibrillation, which was more common in patients admitted on a weekday (39.5% vs. 34.6%; P 5 .05; Table 1). In-hospital complications, in-hospital procedures, and thrombolytic administration were also not significantly different between the 2 groups. Hospital characteristics including hospital bed size, hospital regions, and hospital teaching status were not significantly different in patients who underwent admission on weekends versus weekdays. Length of stay was

not significantly different between the 2 groups; however, mean hospital charges were higher in patients who were admitted on weekends ($155,698 6 295,377 vs. $152,043 6 254,293; P , .0001). Clinical outcomes in the cohort were similar in weekend versus weekday admission including patients discharged with moderate-to-severe disability (61 % vs. 60%; P 5 .5), neurologic complications (5.6 % vs. 4.6%; P 5 .3), cardiac complications (.2 % vs. .6%; P 5 .1), in-hospital mortality (20.1% vs. 20.5%; P 5 .8), and the composite end point (24.4% vs. 23.9%; P 5 .8). In the multivariate analysis, we stratified teaching and nonteaching hospitals. Factors associated with moderate or severe disability at discharge in nonteaching hospitals were weekend admission (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.8; P 5 .04), diagnosis of hypertension (OR, 1.9; 95% CI, 1.0-3.6; P 5.05), and Medicare or Medicaid insurance status (OR, 2.1; 95% CI, 1.1-4.3; P 5 .02; Table 2). Factors associated with moderate or severe disability at discharge in teaching hospitals were age greater than 70 years of age (OR, 1.5; 95% CI, 1.1-2.2; P 5 .02), pneumonia (OR, 4.7; 95% CI, 2.2-10.2; P , .0001), sepsis (OR, 8.2; 95% CI, 1.2-54.8; P 5 .03), intracranial hemorrhage (OR, 3.3; 95% CI, 1.8-6.1; P 5 .0001), and treatment in a Northwest region hospital (OR, 1.7; 95% CI, 1.2-2.4; P 5 .03; Table 3). Factors associated with a lower

Table 2. Multivariable logistic regression analysis of factors associated with moderate-to-severe disability at discharge in patients who underwent thrombectomy at nonteaching hospitals Unadjusted

Adjusted odds*

Factors associated

OR (95% CI)

P value

OR (95% CI)

P value

Hypertension Intracranial hemorrhages Days of hospitalization Weekend Insurance status Medicare/Medicaid

2.3 (1.2-4.4) 8.4 (1.0-67.5)

.009 .04

1.9 (1.0-3.6) 6.6 (.9-51.3)

.05 .06

1.7 (1.1-2.7)

.02

1.6 (1.0-2.8)

.04

2.6 (1.5-4.2)

.0002

2.1 (1.1-4.3)

.02

Abbreviations: OR, odds ratio; CI, confidence interval. *Adjusted for age, sex, and diagnosis of atrial fibrillation.

A. SAAD ET AL.

2712

Table 3. Multivariate logistic regression analysis of factors associated with moderate-to-severe disability at discharge in patients who underwent thrombectomy at teaching hospitals Unadjusted

Adjusted odds*

Factors associated

OR (95% CI)

P value

OR (95% CI)

P value

Age .70 y Dyslipidemia Pneumonia Sepsis Intracranial hemorrhages Nicotine dependence Hospital regions South Northwest Insurance status Medicare/Medicaid No insurance

2.1 (1.6-2.6) .7 (.4-1.0) 5.3 (2.4-11.3) 9.3 (1.4-62.8) 3.7 (2.1-6.8) .4 (.3-.6)

,.0001 .06 ,.0001 .02 ,.0001 ,.0001

1.5 (1.1-2.2) .6 (.4-.9) 4.7 (2.2-10.2) 8.2 (1.2-54.8) 3.3 (1.8-6.1) .6 (.4-.9)

.02 .02 ,.0001 .03 .0001 .006

.6 (.3-.9) 1.7 (1.2-2.4)

.04 .03

1.2 (.9-1.6) .4 (.2-.6)

.08 ,.0001

.5 (.3-.9) 1.7 (1.3-2.4)

.01 .0009

1.8 (1.4-2.2) .3 (.2-.4)

,.0001 ,.0001

Abbreviations: OR, odds ratio; CI, confidence interval. *Adjusted for age, sex, and diagnosis of atrial fibrillation.

likelihood of moderate or severe disability at discharge in teaching hospitals included diagnosis of dyslipidemia (OR, .6; 95% CI, .4-.9; P 5 .02), nicotine dependence (OR, .6; 95% CI, .4-.9; P 5 .006), treatment in a South region hospital (OR, .6; 95% CI, .3-.9; P 5 .04), and no insurance status (OR, .4; 95% CI, .2-.6; P , .0001).

Discussion Although no randomized clinical trials to date have shown thrombectomy for AIS to be superior to intravenous thrombolysis, evidence suggests that time to reperfusion is an important predictor of good clinical outcome. The weekend effect in cardiology has been attributed to delays in mobilizing the cardiac catheterization team, thereby leading to a delay in reperfusion and subsequent poorer outcome.12 Similar factors in AIS thrombectomy may lead to delays in reperfusion and result in poorer clinical outcomes. Although the use of telemedicine can reduce delays in intravenous thrombolytic administration for AIS patients when the neurologist may not be in-house, other organized system-wide strategies are necessary to limit delays in thrombectomy. Our analysis demonstrated a greater likelihood of weekend AIS thrombectomy patients developing moderate-tosevere disability when treated at nonteaching hospitals compared with teaching hospitals. Prior studies comparing teaching versus nonteaching hospital found no disparity in outcomes; however, neither study assessed thrombectomy patients separately.13,14 Other studies have found seasonal differences in teaching hospitals on the mortality of stroke patients.15 Teaching hospitals comprise most (.80%) of the current Joint Commission certified comprehensive stroke centers (CSCs).16 CSCs are more likely to have systems to ensure rapid triage and delivery

of care for AIS patients as well as a multidisciplinary approach as mandated by Joint Commission CSC guidelines.17,18 A teaching hospital or CSC would also be more likely to have a vascular neurologist who would be more experienced at managing AIS patients undergoing thrombectomy than a general neurologist or nonneurologist. Teaching hospitals are also more likely to have neurology residency programs, which include weekend coverage by an in-house neurologist, neurology residents, and/or vascular neurology fellows. This consistency in weekend coverage has been shown to provide more rapid administration of recombinant tissue plasminogen activator in teaching hospitals.19 Large cohort studies have found less disparity between weekend and weekday clinical outcomes in stroke patients treated at CSCs independent of the volume of patients managed.20-22 The weekend effect has also been shown to be reversible when hospitals implement guidelines emulating those of a CSC.23 Given that our analysis was performed using an administrative database, we were unable to determine whether nonteaching hospitals were less likely than teaching hospitals to meet current CSC standards. The primary limitation of this analysis is that unmeasured confounders may have contributed to the reported differences in severity of disability at discharge between patients admitted on weekends and those admitted on weekdays. It is possible that some of these unmeasured variables may explain or mask some of the observations. In summary, we found that AIS patients undergoing thrombectomy on a weekend were more likely to have moderate or severe disability at discharge than a weekday if they were treated at a nonteaching hospital. Our analysis did not identify a weekend effect at teaching hospitals. These findings need to be validated in other

OUTCOMES AFTER THROMBECTOMY FOR AIS

national and international cohorts to determine the impact of the weekend effect on AIS patients undergoing thrombectomy.

References 1. Palmer WL, Bottle A, Davie C, et al. Dying for the weekend: a retrospective cohort study on the association between day of hospital presentation and the quality and safety of stroke care. Arch Neurol 2012;69:1296-1302. 2. Fang J, Saposnik G, Silver FL, et al. Association between weekend hospital presentation and stroke fatality. Neurology 2010;75:1589-1596. 3. Ogbu UC, Westert GP, Slobbe LCJ, et al. A multifaceted look at time of admission and its impact on case-fatality among a cohort of ischaemic stroke patients. J Neurol Neurosurg Psychiatry 2011;82:8-13. 4. Barros JB, Goulart AC, Alencar AP, et al. The influence of the day of the week of hospital admission on the prognosis of stroke patients. Cad Saude Publica 2013;29:769-777. 5. Hoh BL, Yueh-Yun C, Waters MF, et al. Effect of weekend compared with weekday stroke admission on thrombolytic use, in-hospital mortality, discharge disposition, hospital charges, and length of stay in the Nationwide Inpatient Sample Database, 2002 to 2007. Stroke 2010; 41:2323-2328. 6. Rudd AG, Hoffman A, Down C, et al. Access to stroke care in England, Wales and Northern Ireland: the effect of age, gender and weekend admission. Age Ageing 2007;36:247-255. 7. Lees KR, Ford GA, Muir KW, et al. Thrombolytic therapy for acute stroke in the United Kingdom: experience from the Safe Implementation of Thrombolysis in Stroke (SITS) register. QJM 2008;101:863-869. 8. Jauss M, Allendoerfer J, Misselwitz B, et al. Bias in request for medical care and impact on outcome during office and non-office hours in stroke patients. Eur J Neurol 2009;16:1165-1167. 9. Hsieh CY, Chen CH, Chen YC, et al. National survey of thrombolytic therapy for acute ischemic stroke in Taiwan 2003-2010. J Stroke Cerebrovasc Dis 2013;22:e620-e627. 10. http://www.hcup-us.ahrq.gov/db/state/siddist/SID_ Introduction.jsp. Web. Accessed on April 3, 2014.

2713 11. Qureshi AI, Chaudhry SA, Hassan AE, et al. Thrombolytic treatment of patients with acute ischemic stroke related to underlying arterial dissection in the United States. Arch Neurol 2011;68:1536-1542. 12. Kostis WJ, Demissie K, Marcella SW, et al. Weekend versus weekday admission and mortality from myocardial infarction. N Engl J Med 2007;356:1099-1109. 13. Au AG, Padwal RS, Majumdar SR, et al. Patient outcomes in teaching versus nonteaching general internal medicine services: a systematic review and meta-analysis. Acad Med 2014;89:517-523. 14. Papanikolaou PN, Christidi GD, Ioannidis JP. Patient outcomes with teaching versus nonteaching healthcare: a systematic review. PLoS Med 2006;3:e341. 15. Lichtman JH, Jones SB, Wang Y, et al. Seasonal variation in 30-day mortality after stroke: teaching versus nonteaching hospitals. Stroke 2013;44:531-533. 16. http://www.qualitycheck.org/StrokeCertificationList. aspx. Web. Accessed on April 3, 2014. 17. Alberts MJ, Latchaw RE, Selman WR, et al. Recommendations for comprehensive stroke centers: a consensus statement from the Brain Attack Coalition. Stroke 2005; 36:1597-1616. 18. http://www.jointcommission.org/assets/1/18/2012_ DSC_ComprehensiveStrokeCenter1.PDF. Web. Accessed on April 3, 2014. 19. Ford AL, Connor LT, Tan DK, et al. Resident-based acute stroke protocol is expeditious and safe. Stroke 2009; 40:1512-1514. 20. McKinney JS, Deng Y, Kasner SE, et al. Comprehensive stroke centers overcome the weekend versus weekday gap in stroke treatment and mortality. Stroke 2011; 42:2403-2409. 21. Dumont AS, Jabbour PM. Comprehensive stroke centers: eliminating an apparent disparity in stroke care on weekends versus weekdays? Stroke 2011;42: 2380-2382. 22. Albright KC, Savitz SI, Raman R, et al. Comprehensive stroke centers and the ’weekend effect’: the SPOTRIAS experience. Cerebrovasc Dis 2012;34:424-429. 23. Bejot Y, Aboa-Eboule C, Jacquin A, et al. Stroke care organization overcomes the deleterious ’weekend effect’ on 1-month stroke mortality: a population-based study. Eur J Neurol 2013;20:1177-1183.

Clinical outcomes after thrombectomy for acute ischemic stroke on weekends versus weekdays.

The objective of this study was to determine whether clinical outcomes differed in acute ischemic stroke (AIS) patients who underwent thrombectomy on ...
102KB Sizes 0 Downloads 5 Views