background-image: url(./figs/logo.png) background-position: 5% 95% background-size: 35% class: center, middle ### Effect of incident stroke on the risk of dementia over a period of 10 years of follow-up in a cohort of Asian American and White older adults in California .pull.right[ <ins> L. Paloma Rojas-Saunero</ins>, Yixuan Zhou, Eleanor Hayes-Larson, Yingyan Wu, Elizabeth Rose Mayeda <br> **Department of Epidemiology** ] --- ## Motivation - Stroke can precipitate pathological changes in the neurovascular unit leading to loss of structural and functional connectivity that could increase dementia risk. -- - Studies on this topic have very selected samples with minimal (if any) representation of the Asian American population. -- - Previous work had major methodological limitations, including how to account for the fact that stroke increases mortality, which competes with dementia. --- ## Research question - What is the effect of incident stroke in the 10-year-risk of dementia across different Asian American ethnicities and White populations, <ins>if we could remove the effect of stroke on death</ins>? -- - What is the <ins>total effect</ins> of incident stroke in the 10-year-risk of dementia across different Asian American ethnicities and White populations? --- ## Study population - **Study sample:** + Kaiser Permanente Northern California members who participated on the California Men’s Health Study (CMHS) or the Kaiser Permanente Research Program on Genes, Environment and Health Survey (RPGEH) who self-identified as Asian Americans or White. -- - **Eligibility criteria:** + With no history of stroke + With no history of dementia + From 60 to 89 years old --- ## Study Design - **Exposure:** Incident stroke (ischemic stroke, hemorrhagic stroke) - **Outcome:** Incident dementia diagnosis (Alzheimer’s disease, vascular dementia, and non-specific dementia diagnosis) - **Time zero/Baseline:** Time of survey - **End of follow-up:** Time of dementia diagnosis, time of death prior to dementia diagnosis, turning 90 years old --- ## Covariates .pull-left[ **Time-fixed covariates** - Age at survey - Sex/gender - Nativity status - Educational attainment - Health status - Smoking status ] -- .pull-right[ **Time-varying covariates** - Systolic blood pressure (median value/year) - BMI (median value/year) - Cholesterol (median value/year) - Incident diabetes - Incident hypertension - Incident myocardial infarction - Incident congestive heart failure - Incident cancer ] --- ## Statistical Analysis **Weights calculation** - **Inverse probability weights for stroke (IPTW):** so that those who have a stroke and those who don't are comparable at every time-point before stroke. -- - **Inverse probability weights for death over follow-up (IPCW):** to make participants who remain alive after stroke comparable to the no-stroke group over follow-up. --- ## Statistical Analysis **Direct effect:** Plug IPTW x IPCW in a Kaplan-Meier estimator. -- **Total effect:** Plug IPTW in an Aalen-Johannsen estimator. -- **Effect estimation:** Calculate cumulative incidence of dementia and risk ratio at 10 years of follow-up. Bootstrap confidence intervals. --- ### Results .center[ <img src=./figs/stroke_counts.png width="80%"/> ] --- ### Effect of stroke on the risk of dementia on the relative scale .center[ <img src=./figs/RR_SCALE.png width="90%"/> ] --- ## Discussion - The incidence of stroke is high across all Asian American ethnicities and in the White population. -- - Ischemic stroke was more frequently observed, compared to hemorrhagic stroke. -- - There is a large effect of stroke on the risk of dementia if we remove the effect that stroke has on death (_as if we could have prevented it_) and this is consistent across groups. --- ## Acknowledgments This work was supported by NIA R01AG063969, "Alzheimer's disease and related dementias in a diverse cohort of Asian Americans". --- class: center, middle ### Thank you, Gracias!
</i> lp.rojassaunero@ucla.edu</a><br>
<a href="http://twitter.com/palolili23"> </i> @palolili23</a><br>
<a href="https://github.com/palolili23"> </i> @palolili23</a><br> --- class: center, middle ## Extra slides --- ## Example .center[ <img src=./figs/cif_curves_filip.png width="100%"/> ] --- #### Weights assessment - IPTW for Chinese population .center[ <img src=./figs/iptw_chi.png width="95%"/> ]