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Prospective observational study of isoflavone and the risk of stroke recurrence: Potential clinical implications beyond vascular function

Chan, Y. -H., Lau, K. -K., Yiu, K. -H., Siu, C. -W., Chan, H. -T., Li, S. -W., Tam, S., Lam, T. -H., Lau, C. -P., Tse, Hung-Fat
Thejournal of nutrition, health & aging 2012 v.16 no.4 pp. 383-388
food frequency questionnaires, isoflavones, observational studies, patients, randomized clinical trials, regression analysis, risk, risk reduction, stroke
BACKGROUND: Whether isoflavone has any effect on recurrent cardiovascular events is unknown. OBJECTIVE: To investigate the relations between isoflavone intake and the risk of stroke recurrence. SUBJECTS AND METHODS: We recruited 127 consecutive patients with prior history of atherothrombolic/ hemorrhagic stroke (mean age: 67 ± 11 years, 69% male) and prospectively followed up for a mean duration of 30 months. Stroke recurrence and major adverse cardiovascular events (MACE) were documented. Brachial flow-mediated dilatation (FMD) was measured using high-resolution ultrasound. Isoflavone intake was estimated using a validated food frequency questionnaire. RESULTS: Median isoflavone intake was 6.9 (range: 2.1–14.5) mg/day. Isoflavone intake was independently associated with increased FMD (Pearson R=0.23, p=0.012). At 30 months, there were 10 stroke recurrence and 12 MACE. Kaplan-Meier analysis showed that patients with isoflavone intake higher than median value had significantly longer median stroke recurrence-free survival time (19.0 [range: 10.4–27.6] mth versus 5.0 [range: 4.1–5.9] mth, p=0.021) and MACE-free survival time (19.0 [range: 10.4–27.6] mth versus 4.0 [range: 2.4–5.6] mth, p=0.013). Using multivariate cox regression, higher isoflavone intake was an independent predictor for lower risk of stroke recurrence (hazards ratio 0.18 [95%CI: 0.03–0.95], risk reduction 82%, p=0.043) and MACE (hazards ratio 0.16 [95%CI: 0.03–0.84], risk reduction 84%, p=0.030). CONCLUSIONS: Higher isoflavone intake in stroke patients was associated with prolonged recurrence-free survival, and reduced risk of stroke recurrence and MACE, independent of baseline vascular.function. Whether isoflavone may confer clinically significant secondary protection in stroke patients should be further investigated in a randomized controlled trial.