ANNUAL OCT. 31-NOV. 2, 2017 MEETING ARLINGTON, VA Comparative Effectiveness of Rehabilitation Services for Survivors of an Acute Ischemic Stroke Janet Prvu Bettger, ScD, FAHA Associate Professor, Duke University @jpbettger November 1, 2017 On b n beha ehalf o of: Laine Thomas, PhD; Ying Xian, MD, PhD; Li Liang, MS; Jerome J. Federspiel, MD, PhD; Laura E. Webb, BS; Cheryl D. Bushnell, MD, MHS; Pamela W. Duncan, PT, PhD; Eric D. Peterson, MD, MPH; Lee H. Schwamm, MD; Joel Stein, MD; Gregg C. Fonarow, MD; Helen Hoenig, MD, MPH; Cris Montalvo, MA; Mary G. George, MD, MSPH; Barbara J. Lutz, PhD, RN #PCORI2017
ANNUAL MEETING | #PCORI2017 Why Methods Matter • Putting Research to Work for Individual Patients - Using instrumental variable (IV) methods to improve understanding of treatment effects for survivors of acute ischemic stroke 2
ANNUAL MEETING | #PCORI2017 Specific Aim and Approach Aim: To compare care provided in inpatient rehabilitation facilities (IRF) and skilled nursing facilities (SNF) on ischemic stroke patient outcomes Data Sources: American Heart Association (AHA) Get With The Guidelines- Stroke registry linked with Medicare Claims Outcomes: mortality post-discharge, a composite of all-cause rehospitalization or death, days at home Analyses: • Proportional hazards regression with inverse propensity weighting to adjust for measured differences in demographic, clinical and hospital characteristics. • Instrumental variable approach to adjust for both measured and potential unmeasured confounding - IV1 = hospital-specific proportion of patients discharged to IRFs vs SNFs - IV2 = differential distance
ANNUAL MEETING | #PCORI2017 Importance of comparative effective research • Post-acute care (PAC) is the largest driver of variation in Medicare spending • Stroke patients are the highest users of PAC • More than half of stroke patients are discharged from the hospital to receive PAC in an IRF or SNF • Discharge planning and decision making is highly variable
ANNUAL MEETING | #PCORI2017 IRFs and SNFs are Different Interventions* Requirements IRFs SNFs Therapy 3 hours/day No requirement MD Supervision Daily, direct Not daily RN - Nursing 24 hours/day 8 hours/day Length of Stay 16 days (mean) 35 days (mean) Licensed As a hospital As a nursing home Standards Intense, multi- Few regulations guiding disciplinary, coordinated provision of care care * PCORI study used an intention-to-treat (ITT) analysis and did not assess potential differences in delivery of the interventions.
ANNUAL MEETING | #PCORI2017 Exclusion Criteria Individuals who were not suitable candidates for IRF or SNF care and those who would or would not experience the outcome regardless of intervention Of 76,315 ischemic stroke patients, we excluded patients with: • CMS index discharge destination of hospice (community or inpatient) (N=159) • GWTG comfort care measures (earliest documentation of comfort measures only at day 1 or 2) (N=620) • Metastatic cancer documented as a co-occurring condition during index stroke admission • Evidence of LTC in the 6 months prior to index admission (N=562) • Acute care LOS>14 days (N=5,000) • From hospitals with >25% missing on past medical history variables (N=358 patients, 24 hospitals)
ANNUAL MEETING | #PCORI2017 Patient Sample for IRF/SNF Study 69,004 acute ischemic stroke patients who received acute care 1,147 U.S. hospitals Inpatient Rehabilitation Skilled Nursing 34,574 (50.1%) 34,430 (49.9%)
ANNUAL MEETING | #PCORI2017 Baseline Characteristics of Both Groups Demographic Variables IRF SNF Std. Difference* Age mean (std) 78.7 (7.5) 83.0 (7.5) 58.0% Female sex No (%) 19,621 (56.8) 23,186 (67.3) 22.0% Race No (%) Hispanic 1,331 (3.9) 986 (2.9) 7.0% Black 3,416 (9.9) 3,132 (9.1) American Indian or Alaska Native 70 (0.2) 34 (0.1) Asian 483 (1.4) 457 (1.3) Caucasian 28,136 (81.5) 28,619 (83.3) Native Hawaiian or Pacific Islander 63 (0.2) 46 (0.1) UTD 1,043 (3.0) 1,070 (3.1) Caucasian race No (%) 28,168 (81.5) 28,705 (83.4) 5.0% Health Service Use 6 months Prior # hospitalizations in 6mon prior to index 0.3 (0.7) 0.5 (0.8) 22.9% # hospitalizations in 6mon prior to index=0 27,087 (78.5) 23,353 (68.3) 24.2% # hospitalizations in 6mon prior to index=1 5,476 (15.9) 7,356 (21.5) # hospitalizations in 6mon prior to index>=2 1,924 (5.6) 3,470 (10.2) IRF adm in 6mon prior to index 935 (2.7) 655 (1.9) 5.3% SNF adm in 6mon prior to index 1,300 (3.8) 5,718 (16.6) 43.5% * Standardized difference = difference in means or proportions divided by standard error; imbalance defined as absolute value greater than 0.20 or 20% (small effect size)
ANNUAL MEETING | #PCORI2017 Baseline Characteristics of Both Groups Medical History IRF SNF Std. Difference* AMI/CAD 11,332 (32.8) 11,953 (34.7) 4.1% Chronic HF 3,274 (9.5) 4,513 (13.1) 11.5% Diabetes 11,395 (33.0) 10,957 (31.8) 2.4% Peripheral vascular disease 4,221 (12.2) 4,242 (12.3) 0.3% Stroke 11,181 (32.3) 12,931 (37.6) 11.0% Atrial fibrillation 7,671 (22.2) 9,844 (28.6) 14.8% Carotid Stenosis 1,676 (4.8) 1,599 (4.6) 1.0% Dyslipidemia 13,865 (40.1) 11,586 (33.7) 13.4% Hypertension 27,178 (78.6) 27,092 (78.7) 0.2% Smoking 3,931 (11.4) 2,442 (7.1) 14.8% Prosthetic Heart Valve 510 (1.5) 480 (1.4) 0.7% Cancer 1,485 (4.3) 1,746 (5.1) 3.7% COPD 5,964 (17.2) 6,807 (19.8) 6.5% Dementia 1,404 (4.1) 4,813 (14.0) 35.2% Liver disease 199 (0.6) 186 (0.5) 0.5% Peptic ulcer disease 414 (1.2) 509 (1.5) 2.4% Renal disease 3,963 (11.5) 5,238 (15.2) 11.1% Rheumatic disease 984 (2.8) 947 (2.8) 0.6% Disability prior to admission 16,302 (47.2) 14,176 (41.2) 12.1% Medications prior to admission No (%) Antithrombotic (Anticoagulation or Anti 19,420 (56.2) 19,496 (56.6) 0.9% Antihypertensive 25,690 (74.3) 26,114 (75.8) 3.6% Cholesterol reducer 13,718 (39.7) 11,938 (34.7) 10.4% Diabetic medications 8,073 (23.3) 7,724 (22.4) 2.2% * Standardized difference = difference in means or proportions divided by standard error; imbalance defined as absolute value greater than 0.20 or 20% (small effect size)
ANNUAL MEETING | #PCORI2017 Baseline Characteristics of Both Groups Documented in Acute Care IRF SNF Std. Difference* EMS from home/scene 26,004 (75.2) 28,222 (82.0) 16.5% NIHSS mean (std) 8.0 (6.6) 9.5 (7.9) 21.2% tPA in this hospital 2,539 (7.3) 1,361 (4.0) 14.7% Any serious complications of tPA 153 (0.4) 165 (0.5) 0.5% Stroke unit 19,150 (55.4) 16,759 (48.7) 13.5% DVT prophylaxis by hospital day 2 25,819 (74.7) 25,114 (72.9) 3.9% Ambulate independently at discharge 6,594 (19.1) 5,675 (16.5) 6.8% LOS mean (std) 5.3 (2.7) 6.1 (2.9) 29.6% Medications/tx at discharge No (%) Antithrombotic (Anticoagulation or Antiplatelet) 32,601 (94.3) 30,975 (90.0) 16.1% Antihypertensive 28,018 (81.0) 27,571 (80.1) 2.4% Cholesterol reducer 23,467 (67.9) 18,594 (54.0) 28.7% Smoking cessation 4,564 (13.2) 3,084 (9.0) 13.6% Hospital characteristics No (%) Number of Beds 466 (292.6) 420 (287.7) 15.7% Teaching hospital 21,647 (62.6) 19,904 (57.8) 9.8% Rural 1,194 (3.5) 2,246 (6.5) 14.1% Certified PSC 18,833 (54.5) 17,441 (50.7) 7.6% Hospital level composite of QOC measures 0.9 (0.1) 0.9 (0.1) 11.0% Additional factors examined: SES at neighborhood level; in-hospital indicators of patient complexity (devices to support breathing or feeding, catheter use, ICU stay, palliative care), complications during hospital admission (cardiac/respiratory arrest, VT/PE, renal failure, sepsis, decubitus ulcer, UTI) * Standardized difference = difference in means or proportions divided by standard error; imbalance defined as absolute value > than 0.20 or 20% (small effect size)
ANNUAL MEETING | #PCORI2017 Patients Discharged to an IRF vs. SNF are Different Compared with IRF patients, SNF patients : Are older More are female Were hospitalized more in the prior 6 mo. Were in a SNF in the prior 6 mo. More have dementia Have more severe strokes Had a longer hospital LOS
ANNUAL MEETING | #PCORI2017 Factors considered for treatment selection that may be associated with the outcome What we know What we don’t know • Stroke severity • Physical & cognitive function • Ability to ambulate • Able to participate in 3 hours daily rehab • Medicare FFS • Social support • Facility availability Measured confounders Unmeasured confounders
ANNUAL MEETING | #PCORI2017 Instrumental Variables (IV) to Address Confounding IV 1: Practice Patterns IV 2: Differential Distance Proportion of patients in a hospital The distance between the who are discharged to an IRF rather patient’s residence and the than a SNF (calculated as % IRF) nearest IRF minus the distance between the patient’s residence to the nearest SNF Proxy for potential hospital-level Proxy for potential patient-level unmeasured confounding unmeasured confounding
ANNUAL MEETING | #PCORI2017 Testing IV Assumptions: Hospital Practice Patterns for Discharging Patients to Either IRF or SNF Percent of Patients Discharged to an IRF
ANNUAL MEETING | #PCORI2017 Testing IV Assumptions: Practice Patterns • %IRF extremely strong relationship to actual treatment selection - Effect estimate is likely to have good precision and to be representative of a very large portion of the total population %IRF is moderately associated with measured patient and hospital characteristics • that would suggest a possibility for unmeasured confounding in favor of IRF.
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