Stroke Patient Outcomes in US Hospitals Before the Start of the Joint Commission Primary Stroke Center Certification Program
Background and Purpose— The Joint Commission (JC) began certifying Primary Stroke Centers in November 2003. Cross-sectional studies assessing the impact of certification could be biased if these centers had better outcomes before the start of the program. We determined whether hospitals certified within the first years of the JC program had better outcomes than noncertified hospitals before the start of the certification program.
Methods— The study sample included Medicare fee-for-service beneficiaries ≥65 years of age discharged with ischemic stroke in 2002 from 5070 hospitals, 317 of which were JC-certified by June 2007. Hierarchical logistic regression and Cox proportional hazards models were used to compare in-hospital mortality, 30-day mortality, and 30-day readmission for patients treated at future JC-certified versus noncertified hospitals.
Results— Among 366 551 patients, 18% (66 300) were treated at hospitals with centers that were JC-certified within the first few years of the program. These patients were younger, more likely to be white and male, and had fewer comorbidities and hospitalizations within the prior year. Unadjusted in-hospital mortality (4.7% versus 5.5%), 30-day mortality (9.8% versus 11.3%), and readmissions (13.8% versus 14.6%) were lower in the future JC-certified hospitals (all P<0.001). These differences remained after risk adjustment (in-hospital mortality: OR, 0.93; 95% CI, 0.90 to 0.96; 30-day mortality: OR, 0.92; 95% CI, 0.87 to 0.96; 30-day readmission: hazard ratio, 0.97; 95% CI, 0.95 to 0.99).
Conclusions— JC Primary Stroke Center-certified hospitals had better outcomes than noncertified hospitals even before the program began. Cross-sectional studies assessing the effects of stroke center certification need to account for these pre-existing differences.
The Joint Commission (JC) began certifying Primary Stroke Centers in November 2003 based on the recommendations from the Brain Attack Coalition and the American Stroke Association.1–4⇓⇓⇓ The JC awards certification to Primary Stroke Centers that demonstrate compliance with national standards, Primary Stroke Center recommendations, clinical practice guidelines, and performance measurement and improvement activities. Certified centers undergo an on-site review every 2 years and report on quality measures quarterly. Studies that examine the impact of Primary Stroke Center certification have focused on the evaluation of process measures5–8⇓⇓⇓ and information on patient outcomes is limited. Studies analyzing the potential impact of the Primary Stroke Center program using cross-sectional analysis may be biased if hospitals obtaining JC certification have better outcomes even before participating in the program. We hypothesized that patient outcomes from hospitals that obtained JC certification during the early phases of the program differed from those that did not seek certification before the program began. To test this hypothesis, we compared the unadjusted and risk-adjusted 30-day mortality and readmission rates of elderly patients with ischemic stroke treated at hospitals that would become JC-certified within the first few years of the program as compared with those treated at hospitals that did not subsequently become JC-certified within the same time period.
The study population included all Medicare fee-for-service beneficiaries ≥65 years of age hospitalized with a primary discharge diagnosis of ischemic stroke from January 1, 2002, through December 31, 2002, who were identified based on the International Classification of Diseases, Ninth Revision, Clinical Modification (433, 434, 436). Data were obtained from the Medicare Provider Analysis and Review files that included demographic information, primary and secondary discharge diagnosis codes, and procedure codes for each hospitalization for all Medicare fee-for-service patients. Patients who were <65 years of age were not included in the analysis because they do not represent typical Medicare patients. Patients who were discharged from nonacute care facilities, transferred to or from another acute care facility, discharged within 1 day of admission, or who left the hospital against medical advice were excluded. We further limited the cohort to patients with at least 12 months of continuous fee-for-service status before the index ischemic stroke hospitalization to allow assessment of comorbid conditions.
We identified 317 JC-certified Primary Stroke Centers from the start of the program in November 2003 through May 30, 2007, by matching the Medicare provider numbers with an online list of JC-certified centers (Figure 1).9 In addition, we identified hospitals that were certified under state programs in New York,10 Massachusetts,11 and Florida.12 Hospitals with state certification were included in secondary analyses.
Patient and Hospital Characteristics
Patient characteristics included age, sex, race, number of hospitalizations in the previous year (dichotomized as ≥2 versus <2), Deyo comorbidity index13 (dichotomized as ≥3 versus <3), medical history, and comorbid conditions. Conditions included prior stroke, myocardial infarction, congestive heart failure, atrial fibrillation, chronic obstructive pulmonary disease, dementia, diabetes, cancer, coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty, smoking status, and hypertension. These were identified from Medicare Provider Analysis and Review files using International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic codes in the year before the index hospitalization to avoid misclassifying preexisting conditions as complications.
Hospital characteristics (hospital bed size, teaching status, and hospital setting) were obtained from the American Hospital Association’s 2002 Annual Survey Database. Hospital bed size was categorized as <100, 100 to 199, 200 to 299, and ≥300 beds. Hospital setting was categorized as rural (<10 000 population), micropolitan (10 000 to 50 000 population), metropolitan (>50 000 population), and division (part of a metropolitan area with >2.5 million population).
Primary outcomes included in-hospital mortality, defined as death during the index hospitalization, and 30-day all-cause mortality, defined as death from any cause 30 days after the index admission. Mortality data were determined using the Medicare Enrollment Database. The accuracy of ascertainment of vital status using these data resources is high for this age group.14–16⇓⇓ Secondary outcomes, including all-cause hospital readmission and readmission for recurrent vascular disease and common complications, were assessed within 30 days of the index hospital discharge. Patients who died during the index hospitalization or were transferred to another acute care facility were excluded from the 30-day readmission analyses. Recurrent vascular events and complications that warranted readmission within 30 days included recurrent ischemic stroke, any stroke, pneumonia, peripheral arterial disease, urinary tract infection, hip fracture, pulmonary embolism, and coronary artery disease and were identified using the principle diagnostic code at discharge (Supplemental Table I; available at http://stroke.ahajournals.org).
Bivariate analyses were conducted to compare patient characteristics by JC certification status using t tests for continuous variables and χ2 statistics for categorical variables. Hierarchical random effects logistic models were used to assess the difference in odds of mortality between patients admitted to JC-certified and noncertified hospitals while adjusting for patient clustering within hospitals. Readmission rates were compared by JC certification status using Cox proportional hazards models with censoring for deaths. Models were adjusted for patient characteristics and medical history. In secondary analyses, we used the same analytic approach to compare outcomes stratified by certification type (JC and state-certified hospitals) using hospitals that did not receive JC or state certification as the referent group. All analyses were conducted using SAS Version 9.1.3 (SAS Institute Inc, Cary, NC).
A total of 366 551 Medicare ischemic stroke discharges were included in the analyses. The mean age of beneficiaries was 78.2±7.6 years, 56.2% were women, and 85.7% were white (Table 1). A total of 66 300 discharges (18%) were from centers that would become JC-certified within the first few years of the program. Beneficiaries treated at hospitals with future JC-certified Primary Stroke Centers were more likely to be white, younger, and male (P<0.0001 for all comparisons). These patients were less likely to have ≥3 comorbid conditions and had lower rates of prior stroke, congestive heart failure, chronic obstructive pulmonary disease, dementia, and diabetes, but higher rates of hypertension, atrial fibrillation, prior myocardial infarction, and prior cardiac procedures compared with patients who were not treated at hospitals with future JC-certified centers (P<0.001 for all comparisons). They were also more likely to have been hospitalized ≥2 times during the year before the index stroke hospitalization.
Hospitals that received JC Primary Stroke Center certification were larger than those that did not (mean bed size of 419.9±239.9 versus 158.0±164.2, P<0.001; Table 2). Almost one third of certified centers were in teaching hospitals as compared with only 4.7% of noncertified hospitals. JC-certified stroke centers were generally located in more populous areas with >97% situated within a metropolitan or division setting as compared with 60% for noncertified hospitals.
Unadjusted in-hospital mortality was lower in JC-certified hospitals as compared with noncertified hospitals (4.7% versus 5.5%, P<0.001; Figure 2). Outcomes at 30 days were also better for patients treated at hospitals with future JC-certified stroke centers, including mortality (9.8% versus 11.3%, P<0.001), readmission for selected complications (7.3% versus 7.9%, P<0.001), and all-cause readmission (13.8% versus 14.6%, P<0.001). The risk of hospital admission within 30 days was lower for stroke, pneumonia, and peripheral arterial disease but was similar for urinary tract infection, hip fracture, pulmonary embolism, and coronary artery disease (Table 3).
In risk-adjusted analyses (Figure 3), the patients who were treated at hospitals with future JC-certified Primary Stroke Centers had lower risks of death during the acute hospitalization (OR, 0.93; 95% CI, 0.90 to 0.96) and after 30 days (OR, 0.92; 95% CI, 0.87 to 0.96). These patients also had a lower risk of readmission for selected complications (hazard ratio [HR], 0.93; 95% CI, 0.90 to 0.96) and all-cause readmission (HR, 0.97; 95% CI, 0.95 to 0.99) within 30 days after hospital discharge.
Because 3 states (New York, Florida, and Massachusetts) had their own certification programs, we repeated our analyses comparing state-certified centers with noncertified centers. Hospitals with state-certified stroke centers had a lower risk-adjusted 30-day mortality (OR, 0.89; 95% CI, 0.85 to 0.94) as compared with the noncertified hospitals but had comparable 30-day readmission rates (hazard ratio, 1.04; 95% CI, 1.00 to 1.09).
In this study of elderly Medicare fee-for-service beneficiaries, we found that hospitals obtaining early JC Primary Stroke Center certification had lower 30-day patient mortality and readmission rates (all-cause and for selected complications) than noncertified centers at least 11 months before the certification program began. These pre-existing differences need to be accounted for in studies that assess the impact of Primary Stroke Centers on patient outcomes.
Participation in quality improvement efforts and registries that focus on healthcare practices improve adherence with recommended therapies.17–20⇓⇓⇓ It has been suggested that hospitals with quality improvement strategies and stroke units are more experienced and facile in providing interventions such as thrombolytic therapy.6,21⇓ A recent study evaluating the impact of the American Heart Association Get With the Guidelines Stroke program found that the duration of participation, independent of secular trends, was associated with increased adherence to all stroke performance measures.19 Participating hospitals with larger bed capacity, higher annual stroke volume, and teaching status had greater improvements. We found that these characteristics were also more common in hospitals that later received JC certification. Thus, there appear to be differences between the hospitals that obtained Primary Stroke Center certification and those that did not. These pre-existing differences may prepare hospitals to more easily meet the requirements for JC certification resulting in better patient outcomes. In secondary analyses, we also found that state-certified Primary Stroke Centers had lower mortality rates than noncertified centers but not lower 30-day readmission rates as was found for JC-certified hospitals. This may reflect differences in the characteristics of the centers as well as differences in the rigor with which the programs are reviewed.
We found that the risk of hospital admission within 30 days in early JC-certified hospitals was lower for stroke, pneumonia, and peripheral arterial disease but was similar to noncertified hospitals for urinary tract infection, hip fracture, pulmonary embolism, and coronary artery disease. The reasons for this finding are not clear but may in part reflect the low prevalence rates for some of these conditions. In addition, we identified differences in the characteristics of patients who presented to the hospitals that received JC certification within the first few years of the program. These may be due to patient self-selection and/or referral patterns to these hospitals; however, differences in outcomes persisted after adjusting for demographic and clinical factors.
The present study has a number of limitations. The index ischemic stroke cases and complications were ascertained using International Classification of Diseases, Ninth Revision codes and were restricted to hospitalized events. Positive predictive values for the selected codes for ischemic stroke, however, are high,22,23⇓ and there is no reason to expect differences in data coding across institutions by subsequent JC certification status. Although our results only reflect hospitalized events, community-based studies indicate that <15% of strokes are not admitted to the hospital.24,25⇓ Medicare inpatient data do not contain information on medication use; therefore, we were unable to address potential differences in the receipt of recommended acute or secondary preventive therapies, including the administration of tissue plasminogen activator, which was not a reimbursable code at the time of these analyses. Additional factors affecting stroke outcomes such as stroke severity are not reflected in administrative records. Because our analyses are limited to beneficiaries aged >65 years, the data may not be applicable to younger patients with stroke cared for at these hospitals. Our results, however, do reflect the experiences of all fee-for-service patients with ischemic stroke hospitalized within the United States, and the longitudinal data, including outcomes after the index hospitalization, cannot be obtained from current registries.19
Patients treated at hospitals that received Joint Commission certification within the first few years of the program had better outcomes than patients treated at noncertified centers even before the certification program began. To avoid incorrectly attributing possible benefits of Primary Stroke Center certification on patient outcomes, cross-sectional studies need to account for pre-existing differences between certified and noncertified hospitals.
Sources of Funding
The Centers for Medicare & Medicaid Services reviewed and approved the use of its data for this work and approved submission of the manuscript; this approval is based on data use only and does not represent a Centers for Medicare & Medicaid Services endorsement of or comment on the manuscript content. The project described was supported by Grant Number R01NS043322 from the National Institute of Neurological Disorders and Stroke. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Neurological Disorders and Stroke or the National Institutes of Health.
- Received June 26, 2009.
- Accepted July 29, 2009.
- ↵The Joint Commission: Primary Stroke Centers. Available at: www.jointcommission.org/CertificationPrograms/PrimaryStrokeCenters/guide_table_contents.htm. Accessed March 4, 2009.
- ↵Adams R, Acker J, Alberts M, Andrews L, Atkinson R, Fenelon K, Furlan A, Girgus M, Horton K, Hughes R, Koroshetz W, Latchaw R, Magnis E, Mayberg M, Pancioli A, Robertson RM, Shephard T, Smith R, Smith SC Jr, Smith S, Stranne SK, Kenton EJ III, Bashe G, Chavez A, Goldstein L, Hodosh R, Keitel C, Kelly-Hayes M, Leonard A, Morgenstern L, Wood JO. Recommendations for improving the quality of care through stroke centers and systems: an examination of stroke center identification options: multidisciplinary consensus recommendations from the Advisory Working Group on Stroke Center Identification Options of the American Stroke Association. Stroke. 2002; 33: e1–e7.
- ↵Schwamm LH, Pancioli A, Acker JE III, Goldstein LB, Zorowitz RD, Shephard TJ, Moyer P, Gorman M, Johnston SC, Duncan PW, Gorelick P, Frank J, Stranne SK, Smith R, Federspiel W, Horton KB, Magnis E, Adams RJ. Recommendations for the establishment of stroke systems of care: recommendations from the American Stroke Association’s Task Force on the Development of Stroke Systems. Stroke. 2005; 36: 690–703.
- ↵Gropen TI, Gagliano PJ, Blake CA, Sacco RL, Kwiatkowski T, Richmond NJ, Leifer D, Libman R, Azhar S, Daley MB. Quality improvement in acute stroke: the New York State Stroke Center Designation Project. Neurology. 2006; 67: 88–93.
- ↵Douglas VC, Tong DC, Gillum LA, Zhao S, Brass LM, Dostal J, Johnston SC. Do the Brain Attack Coalition’s criteria for stroke centers improve care for ischemic stroke? Neurology. 2005; 64: 422–427.
- ↵Lattimore SU, Chalela J, Davis L, DeGraba T, Ezzeddine M, Haymore J, Nyquist P, Baird AE, Hallenbeck J, Warach S. Impact of establishing a Primary Stroke Center at a community hospital on the use of thrombolytic therapy: the NINDS Suburban Hospital Stroke Center experience. Stroke. 2003; 34: e55–e57.
- ↵Stradling D, Yu W, Langdorf ML, Tsai F, Kostanian V, Hasso AN, Welbourne SJ, Schooley Y, Fisher MJ, Cramer SC. Stroke care delivery before vs after JCAHO stroke center certification. Neurology. 2007; 68: 469–470.
- ↵List of JC-certified centers. Available at: www.jointcommission.org/qualitycheck/certified_orgs.htm. Accessed June 26, 2009.
- ↵List of New York state-certified centers. Available at: www.health.state.ny.us/nysdoh/ems/stroke/stroke.htm. Accessed March 4, 2009.
- ↵List of Massachusetts state-certified centers. Available at: www.mass.gov/?pageID=eohhs2terminal&L=7&L0=Home&L1=Provider&L2=Certification%2c+Licensure%2c+and+Registration&L3=Facilities&L4=Health+Care+Facilities+and+Programs&L5=Hospitals&L6=Stroke+Services&sid=Eeohhs2&b=terminalcontent&f=dph_quality_healthcare_p_stroke_tracking&csid=Eeohhs2. Accessed March 4, 2009.
- ↵List of Florida state-certified centers. Available at: http://ahca.myflorida.com/MCHQ/Health_Facility_Regulation/Hospital_Outpatient/hospital.shtml. Accessed March 4, 2009.
- ↵Boyle CA, Decoufle P. National sources of vital status information: extent of coverage and possible selectivity in reporting. Am J Epidemiol. 1990; 131: 160–168.
- ↵Curb JD, Ford CE, Pressel S, Palmer M, Babcock C, Hawkins CM. Ascertainment of vital status through the National Death Index and the Social Security Administration. Am J Epidemiol. 1985; 121: 754–766.
- ↵The impact of standardized stroke orders on adherence to best practices. Neurology. 2005; 65: 360–365.
- ↵Schwamm LH, Fonarow GC, Reeves MJ, Pan W, Frankel MR, Smith EE, Ellrodt G, Cannon CP, Liang L, Peterson E, Labresh KA. Get With the Guidelines–Stroke is associated with sustained improvement in care for patients hospitalized with acute stroke or transient ischemic attack. Circulation. 2009; 119: 107–115.
- ↵Gillum LA, Johnston SC. Characteristics of academic medical centers and ischemic stroke outcomes. Stroke. 2001; 32: 2137–2142.
- ↵Goldstein LB. Accuracy of ICD-9-CM coding for the identification of patients with acute ischemic stroke: effect of modifier codes. Stroke. 1998; 29: 1602–1604.
- ↵Tirschwell DL, Longstreth WT Jr. Validating administrative data in stroke research. Stroke. 2002; 33: 2465–2470.
- ↵Leibson CL, Naessens JM, Brown RD, Whisnant JP. Accuracy of hospital discharge abstracts for identifying stroke. Stroke. 1994; 25: 2348–2355.
- ↵Williams GR, Jiang JG, Matchar DB, Samsa GP. Incidence and occurrence of total (first-ever and recurrent) stroke. Stroke. 1999; 30: 2523–2528.