1. In this population-based prospective cohort study, the trajectory of increasing disability was significantly steeper after stroke than after myocardial infarction.
2. Further study to determine if this accelerated disability trajectory state after stroke can be intervened on will be needed.
Evidence Rating Level: 2 (Good)
Study Rundown: It is thought that stroke causes disability acutely, and after the recovery period, the slope of ones disability trajectory is the same as those without strokes. However, this paradigm may not be accurate. It is now proposed that vascular brain injury may accelerate the disability and deterioration of functional status over time, even without recurrent events. This population-based prospective cohort study aimed to test whether the increase in long-term disability is steeper after than before the event for ischemic stroke but not myocardial infarction (MI).
The trajectory of increasing disability became significantly steeper after stroke but not after MI. The annual increase in disability after stroke more than tripled after stroke where the increase in disability before and MI did not differ significantly. Strengths of this study included its use of a large nationally-based representative cohort of elderly community-dwelling participants, however the sample size was small due to the need for before and after disability measurements to determine the trajectory. Also, details regarding the location, size and severity of stroke were not available and thus not accounted for in trajectory calculations.
In-Depth [prospective cohort]: This large-scale prospective cohort study was conducted using patient data from the Cardiovascular Health Study (1989-2013) and included community dwelling adults aged 65 and older from a sex- and age-stratified random sample of Medicare-eligible individuals in 4 states. Individuals needing a wheelchair, receiving hospice care or undergoing radiotherapy were also excluded. Baseline sociodemographic, functional and health data were gathered. Participants were followed for a mean (SD) of 13 (6.2) years. Exposure of interest was stroke (classified into ischemic, hemorrhagic or unknown) and MI (based on clinical history, elevated cardiac enzymes and ECG changes). The outcomes of interest were disability as assessed annually by activities of daily living (ADL) and instrumental ADL (IADL) scales and determined before and after the exposure of interest.
The mean age of the cohort (n = 5888) was 72.8 years old. There were similar incidences of stroke (n = 382) and MI (n = 395) during follow up. There were a similar mean (SD) number of visits for assessment before stroke (3.7 [2.4]) and MI (3.8 [2.5]) and after stroke (3.7 [2.3]) and MI (3.8 [2.4]). As expected there was a greater increase in disability around the time of the event for stroke as compared to MI (stroke: 0.88 points on disability scale; 95% CI 0.57-1.20, p < 0.001, MI: 0.20 points on disability scale, 95% CI 0.06-0.35, p = 0.006). The annual increase in disability after stroke more than tripled after stroke (before stroke: 0.06 points on disability scale per year; 95% CI 0.002-0.12, p = 0.04, after stroke: 0.15 additional points per year; 95% CI 0.004-0.30, p = 0.04). There was no significant difference in the annual increase in disability before or after MI (before MI: 0.04 points per year; 95% CI 0.004-0.08, p = 0.03; after MI: 0.02 additional points per year; 95% CI -0.07-0.11, p = 0.69).
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