Purpose: To clarify the association between the metabolic syndrome (MS) and stroke incidence with a prospective cohort study in a rural community.
Methods: We selected 4,627 people aged > or =40 years without any past history of stroke from total 4,672 participants of health checkups during 1996 to 1998 in O City, Ehime prefecture. These were followed until Dec 31, 2002 and assessed for incident stroke based on the stroke registration system in the whole community. MS was defined using baseline data for waist circumference and three risk factors: elevated blood pressure, dyslipidemia, and glucose intolerance. Sex and age-adjusted relative risks (RR) for incident stroke were estimated using Cox's proportional hazard model, and population attributable risks (PAR) were also calculated.
Results: During the mean 5.7 year-follow-up, 88 incident strokes (50 in men and 38 in women) were recorded; 11.4% cerebral hemorrhage; 5.7% subarachnoid hemorrhage; and 83.0% cerebral infarction. Percentages of individuals with MS in the stroke and non-stroke groups were 6.8% and 6.4%, respectively, with no significant different between the two. The highest PAR was found among individuals with a normal waist and one risk factor (36.3%). The sex and age-adjusted RR for MS and incident stroke was not significantly elevated, using subjects with a normal waist circumference and 0 risk factors as a reference group (RR, 1.00); however, the RR of persons with a normal waist level plus one or more risks was 2.53 (95% CI, 1.14-5.58), and that for individuals with a high waist circumference and > or = 1 risk factors, including MS, was 2.66 (95% CI, 1.14-6.21).
Conclusion: The risk of incident stroke is increased in people with risk factor aggregation, regardless of visceral fat conditions. Since the PAR was higher for people with a normal waist circumference than a high waist circumference in this population, the results suggest that a health policy focusing on MS for stroke prevention would not be effective in rural communities in Japan.