Jan. 07, 2021
The incidence of stroke is declining among older adults in the United States, and advances in acute therapies are improving overall stroke survival rates. However, because age remains an unmodifiable risk factor for stroke, and because the population of Americans age 65 and older is expected to double over the next 40 years, stroke prevalence and its associated costs are expected to increase substantially. Thus, the ability to determine specific variables predictive of stroke outcomes will help providers prepare for the medical rehabilitation services that those living with stroke-related neurological impairment may need.
According to Allen W. Brown, M.D., a physiatrist and director of brain rehabilitation research at Mayo Clinic's campus in Rochester, Minnesota, prior studies seeking to identify variables that help predict patient outcomes after stroke were often limited by relying on small data sample sizes. Addressing that limitation, Dr. Brown and colleagues conducted research using the Uniform Data System for Medical Rehabilitation (UDSMR), a large, nationally representative patient data repository of inpatient rehabilitation outcomes. The UDSMR contains data collected from the Centers for Medicare & Medicaid Services-mandated Inpatient Rehabilitation Facility-Patient Assessment Instrument.
Dr. Brown and colleagues first published an analysis of stroke outcomes using UDSMR data in Stroke in 2015. That study suggested that the factor most predictive of outcomes at discharge from inpatient rehabilitation for stroke is a person's functional status.
In a follow-up study, Dr. Brown and colleagues used a large subset of the original data sample to identify key factors that predict functional independence and living setting three months after discharge from inpatient rehabilitation. The results of that second investigation were published in the Journal of Stroke and Cerebrovascular Diseases in 2020.
The UDSMR includes demographic, administrative and clinical variables collected at rehabilitation admission, at discharge and at three-months after discharge from an inpatient facility. Mayo Clinic researchers randomly selected a group of 16,346 study subjects (80% white; 50% women; mean age, 70.3 years) with a diagnosis of stroke (97% ischemic) who were hospitalized for inpatient rehabilitation from 2005 through 2007. Within this population of 16,346 patients, they focused on the functional independence measure (FIM) instrument score and living setting three months after rehabilitation hospital discharge as the primary outcome measures. The FIM is a validated and reliable instrument for measuring activity limitations. It focuses on 18 items that evaluate a person's motor and cognitive function on the basis of the degree of help required to complete tasks, and scores these on a scale of 1 (total dependence to perform the task) to 7 (total independence).
The FIM scores of the 16,346 study subjects were determined on admission to an inpatient rehabilitation setting, at discharge and at three months after discharge. Inpatient and discharge FIM assessments were conducted by clinicians at the inpatient facilities. Follow-up FIM assessments were conducted via telephone survey by FIM-credentialed surveyors. Data about living setting three months after rehabilitation discharge also were recorded during the telephone survey.
Mayo Clinic researchers examined a long list of possible predictor variables, including:
- Age at admission, sex, race, geographic region, marital status
- Time from onset of symptoms to admission to inpatient rehabilitation (termed onset days)
- Total length of rehabilitation stay
- Prehospital vocational category, prehospital living with status and impairment code case-mix group (fiscal year 2007) injury severity stratification
- FIM total (which includes motor and cognitive subscores) at admission and discharge, including FIM walk/wheelchair status, distance walked, and whether walking or wheelchair use is the primary mobility mode at admission and discharge; and total gain in FIM
- Discharge living with status and discharge setting
- Length of stay efficiency (the difference in FIM score from admission to discharge, divided by length of stay in days)
Researchers also analyzed the following stroke-related comorbid conditions: dysphagia; dominant, nondominant hemiparesis and hemiplegia; gait disorder; aphasia; ataxia; facial weakness; neglect; impaired visual fields; and neurogenic bladder.
According to Dr. Brown, this analysis of a large, nationally representative data set contributes two unique and important findings.
FIM at discharge from rehabilitation is the strongest predictor of functional independence at three months, even when compared with multiple variables found to be predictive in other samples, including stroke-related comorbid conditions. The initial rehabilitation discharge location is the strongest predictor of living location at three months when compared with multiple other covariates.
"Although we examined multiple predictor variables and stroke-related comorbid conditions that were previously thought to be predictive," explains Dr. Brown, "the strongest predictors of functional independence measure score and living setting at three months were those same factors at rehabilitation discharge."
Dr. Brown emphasizes that these findings also suggest that functional gains made during rehabilitation hospitalization that enable independent living are sustainable and may even improve with time.
"Our data show that the proportion of patients living at home increased over the follow-up period, from 82% at rehabilitation discharge to 92% at three months after discharge," says Dr. Brown. "This change indicates that functional recovery can continue after discharge, and that even patients with significant impairment are able to return home after receiving additional rehabilitation services."
The study also validated a number of what Dr. Brown calls intuitive findings indicating that data acquired at the point in time closest to the outcome of interest are better predictors of that outcome. "We confirmed that data collected at rehabilitation discharge are better predictors than those collected at admission, and that the patients who are most impaired and functionally limited at discharge are those most likely to need a skilled level of care at three months after discharge," explains Dr. Brown.
Overall, Dr. Brown and colleagues are hopeful that these data can inform clinicians, patients with stroke and their families about what to expect in the months after hospital discharge. They also acknowledge that their study has limitations. Although functional independence at rehabilitation discharge and discharge location were the strongest outcome predictors at three months when compared with other variables shown to be predictive in previous reports, the strength of this prediction was modest. This suggests that other factors may influence post-acute outcomes.
"Looking ahead, including educational status, socioeconomic factors and brain imaging may improve future efforts to refine predictive modeling," explains Dr. Brown.
For more information
Brown AW, et al. Measure of functional independence dominates discharge outcome prediction after inpatient rehabilitation for stroke. Stroke. 2015;46:1038-44.
Brown AW, et al. Functional performance and discharge setting predict outcomes 3 months after rehabilitation hospitalization for stroke. Journal of Stroke and Cerebrovascular Diseases. 2020;29:104746.