| Background— Stroke is a major cause of serious disability and death. Approximately 30000 people have a stroke in Sweden each year. Although stroke mortality appears to be declining, the picture is less clear regarding the incidence. Data on stroke trends for Sweden as a whole have not previously been reported, but regional studies have indicated increasing and decreasing trends for stroke incidence in younger age groups during the past 20 years. If the incidence of stroke among younger persons of working age is increasing in Sweden, the consequences for the health care system, as well as for other support systems, will be considerable. Reliable information concerning stroke trends may increase our understanding of the causes of the disease and improve priority setting in the health care system.Although obesity is well recognized as a risk factor for cardiovascular diseases, the relationship between obesity and stroke remains less clear. In addition, abdominal obesity measured by waist-to-hip ratio (WHR) is related to an increased risk of coronary heart disease, but few studies have examined the relationship between abdominal obesity and ischemic stroke or intracerebral haemorrhage separately. The relationship between alcohol intake and risk of stroke remains controversial. Few studies have examined the contribution of different beverage types to stroke, and its main subtype, especially in young women. Oral contraceptives (OCs) have been widly used in western countries, and affected by the reproductive factors of women in different life periods. Controversy over whether Ocs is a cause of stroke has been raging since the early 1960s and the debate continous for the findings have been contradictory. The relationships between reproductive factors and risk of stroke have rarely been studied.Purpose— Our aim was to prospectively examine whether1. Body mass index, 2.Waist-to-hip ratio (WHR), or waist circulation alone, 3.The change of body shape from age 7, age 18 to enrolment, 4.Physical activity, 5.alcohol intake and types of beverage, 6.smoking and passive smoking in different life periods, 7. OCs use and reproductive factors,8.educatioanl attainment, 9.number of siblings is a risk factor for ischemic stroke or haemorrhage stroke.Methods— Women Lifestyle and Health Study cohort included 49206 Swedish women who were aged 29-49 in 1991-1992 when they completed an extensive questionnaire on personal characteristics. Linkage to various population-based registries ensured complete follow-up from the date of receipt of the returned questionnaire through the date of age 55,diagnosis of first-ever stroke, or to the date of emigration or death,or to the end of follow up(Dec 31,2002) whichever occurred first. All cases were indentified from the Inpatient Register with a diagnosis of ischemic stroke (ICD-9-434; ICD-10-I63), intracerebral hemorrhage, (ICD-9-431; ICD-10-161), and undetetermined pathological type, (ICD-9-436; ICD-10-I64) Anthropometric measures including height, body weight at enrolment, weight at age 18, body shape at age 7, and waist and hip circumference. Information on self-perceived physical activity levels at age 14,age 30 and at enrolment was collected as scores from l(lowest) to 5(highest). Subsequently, the variables were compiled into three levels of each age period: low (score 1 and 2) middle (score 3) and high (score 4 and 5). Exposure to smoking and alcohol, including the questions concerning various beverage they have taken each week and how many cigarrte they smoked each day during the different life periods were collected at enrolment. OCs use classifed as never-use and ever-use. The age at first use of OC and the duration of OC use were also included in the final model. The reproductive factors included age at menarch, age at first child birth, parity, duration of breasfeeding were devided into three to four groups according to its distribution in study cohort. Educational attainment and number of sibling were also collected at enrolment. Cox proportional hazard model was used to estimate relative risk. All statistical tests were two sided.Results— 1.Characteristics of the cohort: During the average follow-up of 10.3 years, weidentified 223 cases of stroke, 129 of which were ischemic stroke (IS), 80 of which were intracerebral hemorrhage (ICH) and 14 of unknown type. The patients of ischemic stroke tend to be older and have a lower attainment of education, and have more prevalence of overweight and obesity, smoked more and have a larger cumulative pack-year of ever smoked. They often have drunk fewer wines and more beers. The patients of hemorrhagic stroke tendto be older and have more siblings, the prevalence of WHR>0.88 tend to be more. They often had more parity and the young age at first childbirth. Compared with the hemorrhagic stroke, the ischemic stroke were younger, smoked less and begin to use OC at a young age. 2.Results of mono-variable analysis: A.the risk factors of ischemic stroke were: BMI^30, WHR^0.88, WHER^0.54, Waist2s90, fat at age 7, body shape change to fat from age7 to agell8, smoking, age at first OC use ^21, cumulative months of braest feeding ^9, hypertension and diabetes mellitus; high level of physical activity, consumption of moderate beers (^200 ml/week) , consumption of wine ( ^100 ml/week) , education attainment over 12 years and age at first child birth over age 25 were protective factors. B.the risk factors of hemorrhagic stroke were:WHR^0.84,waist5:90^ smoking, passive smoking at enrolment, sibling > 5 ,hypertension and diabetes mellitus; high level of physical activity at enrolment and at age 3 0,moderate alcohol intake (<20g/week and <42g/week ) and wine consumption (^ 100 ml/week and^300 ml/week) were protective factors.3.Results of muti-variable model: The incidence(l/100000personyear) of age group 29-35, 30-40, 40-45 and >45 for IS were 2.86, 9.47, 12.73, 42.57 respectively. For ICH the incidence were 0, 9.47, 8.98, 24.62 respectively. After adjustment for age, the risk of IS increased with overweight(25 |
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