Multiple Chronic Conditions and Post-Stroke Functional Outcome

Abstract

Stroke is a leading cause of disability in the United States (US) and the number of disabled stroke survivors will rise with the aging population. The aging of the US population will also lead to an increase in the prevalence of multiple chronic conditions (MCC) at stroke onset, which impacts post-stroke functional outcome (FO), although current evidence is inconsistent. The goal of this dissertation was to advance the understanding of MCC in post-stroke functional outcome through a systematic literature review and data analyses using a bi-ethnic population-based stroke cohort. Specifically, this dissertation investigated the association between MCC and post-stroke FO by 1) summarizing the findings of previous studies that have investigated the relationship between MCC and FO after ischemic stroke using MCC indices, 2) developing and internally validating a new MCC index to predict post-stroke FO using machine learning techniques, and 3) investigating the contribution of MCC to ethnic disparities in post-stroke FO between Mexican American (MA) and non-Hispanic white (NHW) stroke patients using the new index. The systematic literature review showed that hospital-based prognostic studies for post-stroke FO predominantly used the Charlson Comorbidity Index (CCI) and the Modified CCI (mCCI) to measure MCC burden. The negative association between MCC and FO was statistically significant in the meta-analysis. We identified several novel predictors of post-stroke FO and developed a new MCC index among ischemic stroke patients. The new MCC index was validated to improve the prediction of post-stroke FO at 90 days and outperformed the mCCI. MA stroke patients have significantly greater age-adjusted MCC burden at stroke onset compared to NHWs. MCC measured by the new index was found to be an important contributor to worse FO at 90 days in MAs compared with NHWs, although effect modification of the MCC-FO outcome association by ethnicity was not statistically significant. This dissertation research confirmed that MCC is an important predictor for post-stroke FO. External validation is needed before the application of this index in other stroke populations. Accurate measurement of the MCC burden in stroke patients is important for more precise prognosis in post-stroke FO, which could inform stroke treatment, post-acute care, and intervention efforts to mitigate post-stroke functional impairment, promote functional gain and lessen ethnic disparities in post-stroke FO.