Abstract
Background:
Previous research in our population showed a steeper long-term decline in functional status after first ischemic stroke among those with Medicaid or no insurance compared to those with Medicare or private insurance. With only post-stroke data, it was unknown whether these findings were caused by the stroke. We sought to compare the long-term trajectory of functional status before and after ischemic stroke.
Methods:
The Northern Manhattan Study contains a prospective, population-based study of stroke-free individuals >40 years of age, followed for a median of 10 years. The Barthel index (BI) was assessed annually. Generalized estimating equations were used to assess functional decline over time before and after stroke. The 6 months after stroke were ignored, since the course of recovery during this period is well documented, and our interest was the long-term course of functional status. Follow-up was censored at the time of recurrent stroke. Sociodemographic and medical risk factors were included and results were stratified by insurance status. Linearity of the curves was evaluated by plotting residuals against time and with a lowess curve.
Results:
Among 3298 participants, 261 had an ischemic stroke during follow-up, of which 51 died within 6 months of stroke. Among the remaining 210 participants, mean age at stroke (standard deviation) was 77+9 years, 38% were male, 52% were Hispanic, 37% had diabetes, and 31% had coronary artery disease. There was no difference in functional decline over time before and after stroke (p= 0.51), with a decline of 0.96 BI points per year before stroke (p<.0001) and 1.24 after stroke (p=0.001). However, when stratified by insurance status, among those with Medicaid or no insurance, in a fully adjusted model, there was a difference in slope before and after stroke (p=0.04), with a decline of 0.58 BI points per year before stroke (p=0.02) and 1.94 after stroke (p=0.001). Other predictors of worse functional status were increasing age, female sex, diabetes, and being married.
Conclusion:
In this large, prospective, population-based study with long-term follow-up, there was a significantly steeper decline in functional status after ischemic stroke compared to before stroke among those with Medicaid or no insurance, after adjusting for confounders. The cause of this differential decline is not known but may be related to poor control of risk factors, silent strokes, or an effect of socioeconomic status.