Ahmed, Ayesha;
(2024)
Primary prevention of stroke in high stroke risk populations: examining impact of modifiable risk factors and risk stratification in Older Adults and South Asians using two longitudinal cohorts.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Background: Older adults and South Asians (SAs) carry high stroke burden. Primary prevention of stroke involves population-level and high-risk approaches for risk factor modification. However, impact of risk factors and validity of risk assessment tools can vary across age and ethnicity. Additionally, whether N-terminal-pro-B-type-natriuretic-peptide (NT-proBNP), reflecting subclinical cardiac dysfunction, improves stroke risk prediction in these groups is unclear.// Aims: To inform primary prevention of stroke in cardiovascular disease (CVD) free older adults and SAs by examining impact of smoking, body mass index, physical activity, diet, cholesterol, blood pressure (BP) and glucose levels using American Heart Association’s cardiovascular health (CVH) model; risk assessment; and contribution of NT-proBNP to risk stratification.// Methods: The thesis used data from British Regional Heart Study (BRHS) following men (40-59y) for forty years, and Southall and Brent Revisited Study following SAs (40-69y) for two decades; to estimate population attributable fraction (PAF) of stroke resulting from sub-optimal CVH. Stroke-specific and composite-CVD risk prediction tools were validated for stroke risk in older BRHS men. Incremental value of NT-proBNP in classifying stroke risk was examined in both cohorts.// Results: In BRHS men, PAF of stroke decreased from 39% (95%CI 10-58) in midlife to 6% (-17-25) in older age, with BP the main metric retaining a (reduced) contribution. Among SAs, PAF was 36% (11-53) with main contributions from BP, glucose, and body mass index. In older BRHS men, all risk tools discriminated stroke risk weakly, with comparable risk prediction overall. Using recommended CVD prevention thresholds, composite-CVD tools had poor specificity for stroke. NT-proBNP modestly improved reclassification of older BRHS men and SAs without incident stroke.// Conclusions: Impact of CVH on stroke decreases with age. Among SAs, optimal midlife CVH can avert >1/3rd of incident stroke. Stroke risk discrimination in older adults requires improvement. NT-proBNP augments stroke risk prediction among both groups.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Primary prevention of stroke in high stroke risk populations: examining impact of modifiable risk factors and risk stratification in Older Adults and South Asians using two longitudinal cohorts |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Epidemiology and Health UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Epidemiology and Health > Primary Care and Population Health |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10194966 |
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