Background The American Heart Association’s model of ideal cardiovascular health (CVH), based on 7 well-known and modifiable health factors (body mass index, blood pressure (BP), glucose, cholesterol, physical activity, smoking and diet - Life’s Simple 7 or LS7) was developed to promote primordial prevention of cardiovascular disease (CVD), including stroke. Stroke burden rises sharply with age. However most research exploring CVH has been conducted in middle-aged participants. In the British Regional Heart Study (BRHS), we prospectively explored associations of each LS7 factor and composite CVH scores with stroke in middle and older age; and associations between CVH trajectories and stroke incidence in later life.
Methods The BRHS is a prospective study of men recruited in 1978–1980 (aged 40–59y, baseline) and followed up for CVD events. The men were re-examined at 20 years (Q20). All components of LS7 were measured at both time points except baseline diet. Men without pre-existing CVD were followed from baseline (mean age 50y, n=6612) and again from Q20 (mean age 69y, n=3798) for a median period of 20y and 16y respectively. Cox models estimated risk of stroke as adjusted hazard ratios (HRs) for ideal and intermediate vs poor levels of LS7 factors; for composite CVH scores; and for 4 CVH trajectory groups based on transitions in CVH status (low/high) from baseline to Q20 - Low-Low, Low-High, High-Low and High-High.
Results Stroke event rates for baseline and Q20 cohorts were 3.1 and 8.4 per 1000 person years respectively. At baseline, healthier levels of three LS7 - BP, physical activity and smoking were associated with reduced risk of stroke. HRs [95% Confidence Intervals] for intermediate and ideal (vs poor) were 0.62 [0.49, 0.79] and 0.41 [0.24, 0.69] for BP; 0.68 [0.49, 0.95] and 0.55 [0.39, 0.79] for physical activity; and 0.68 [0.54, 0.86] and 0.57 [0.43, 0.77] for smoking. For exposures measured at Q20, only BP maintained a protective association (HRs 0.84 [0.66, 1.06] and 0.50 [0.30, 0.84] for intermediate and ideal levels respectively). Protection from each unit increase in overall CVH scores also weakened with age. With reference to the Low-Low trajectory, all trajectories were generally associated with reduced risk. The HRs were Low-High 0.57 (0.41, 0.79); High-Low 0.85 (0.61, 1.19) and High-High 0.77 (0.58, 1.03) respectively.
Conclusion Not all components of CVH individually influence stroke. While the association between CVH and stroke weakens with age, improving overall CVH may bring some benefit even in later life.
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