Trends in stroke incidence rates and stroke risk f

Authors: Renske G Wieberdink M Arfan Ikram Albert Hofman Peter J Koudstaal Monique M B Breteler

Publish Date: 2012/03/17

Volume: 27, Issue: 4, Pages: 287-295

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Abstract

Stroke incidence rates have decreased in developed countries over the past 40 years but trends vary across populations We investigated whether ageandsexspecific stroke incidence rates and associated risk factors as well as preventive medication use have changed in Rotterdam in the Netherlands during the last two decades The study was part of the Rotterdam Study a large populationbased cohort study among elderly people Participants were 10994 men and women aged 55–94 years who were strokefree at baseline Trends were calculated by comparing the 1990 subcohort n = 7516 baseline 1990–1993 with the 2000 subcohort n = 2883 baseline 2000–2001 Poisson regression was used to calculate incidence rates and incidence rate ratios in ageandsexspecific strata We further compared the prevalence of stroke risk factors and preventive medication use in the two subcohorts In the 1990 subcohort 467 strokes occurred during 45428 person years in the 2000 subcohort 115 strokes occurred in 18356 person years Comparing the subcohorts incidence rates decreased by 34 in men but remained unchanged in women Blood pressure levels increased between 1990 and 2000 whereas the proportion of current cigarette smokers decreased in men but not in women There was a strong increase in medication use for treatment of stroke risk factors across all age categories in both sexes Our findings suggest that in Rotterdam between 1990 and 2008 stroke incidence rates have decreased in men but not in womenThe worldwide burden of stroke is predicted to increase due to increased life expectancy and population aging 1 On the other hand in several highincome countries stroke mortality trends were predicted to decrease in the decades ahead 2 Furthermore agespecific stroke incidence rates have decreased in highincome countries during the past 40 years 3 However there are substantial geographic differences in stroke incidence rates and trends over time 4 Currently it is not clear if stroke incidence rates are changing in the NetherlandsStroke is increasingly recognized as a disease that can be prevented 5 Knowledge of modifiable risk factors and the availability of primary preventive medication has resulted in the development of evidencebased guidelines for the treatment of highrisk individuals 6 Furthermore public health campaigns were initiated to improve awareness of risk factors and to promote lifestyle changes on a population level Whether these interventions resulted in a favorable risk factor profile of the general population and in parallel in a reduction in stroke events is unknown and requires investigation Additionally studies suggest that women may receive suboptimal treatment of cardiovascular risk factors because of lower perception of risk by treating physicians 7 Therefore sexspecific changes in risk factor profiles and stroke incidence rates are of particular interestThe aim of the present study was to describe temporal trends in stroke incidence rates in the Netherlands during the past 20 years and to investigate changes in preventive medication use and the prevalence and severity of stroke risk factors We particularly aimed to compare patterns between men and women All analyses were based on data from the Rotterdam Study a large prospective populationbased cohort study among elderly people living in the city of Rotterdam in the NetherlandsThe Rotterdam Study is an ongoing prospective populationbased cohort study that focuses on causes and consequences of chronic and disabling diseases in the elderly 8 The cohort started in 1990 and included 7983 participants aged ≥55 years living in Ommoord a district of the city of Rotterdam in the Netherlands participation rate 78 In 2000 the cohort was expanded with 3011 people who had reached the age of 55 or had moved into the district since the start of the study response rate 67 The study was approved by the Medical Ethics Committee of the Erasmus MC University Medical Center and all participants gave written informed consent to participate in the studyThe present study included participants of the 1990 subcohort and the 2000 subcohort who were aged 55–94 at baseline n = 10944 Participants who had had a stroke before baseline n = 361 and participants who had not signed consent for the collection of followup data from general practitioners n = 184 were excluded This resulted in 10399 participants in the population for analysis 1990 subcohort n = 7516 2000 subcohort n = 2883Trained research physicians visited all participants at home for filling in standardized questionnaires about their health status medical history and current medication use Data on female hormone use including both oral contraceptive use and hormone replacement therapy for menopausal complaints were collected at baseline and classified as current use or ever use Subsequently participants visited the research center twice for physical examinations and blood sampling Cigarette smoking behavior was classified as current past or never Blood pressure was measured twice at the right brachial artery with a randomzero sphygmomanometer after 5 min of rest while the subject was in a sitting position Hypertension grade I was defined as a diastolic blood pressure of 90–99 mm Hg or a systolic blood pressure of 140–159 mm Hg Hypertension grade II was defined as a diastolic or systolic blood pressure of ≥100/160 mm Hg and/or use of blood pressurelowering medication 9 Total serum cholesterol highdensity lipoprotein cholesterol and glucose levels were measured using an automated enzymatic procedure Nonfasting blood samples were obtained from the 1990 subcohort fasting blood samples from the 2000 subcohort Diabetes mellitus was defined as a fasting glucose level ≥70 mmol/L a nonfasting or postload serum glucose level ≥111 mmol/L and/or the use of blood glucoselowering drugs Body mass index was calculated as weight in kilograms divided by the square of height in meters Atrial fibrillation was diagnosed when observed on ECG during the visit to the research center or when reported in medical records History of myocardial infarction was considered positive when selfreported during the interview observed on ECG during the center visit and/or confirmed in medical recordsStroke was defined according to WHO criteria as a syndrome of rapidly developing clinical signs of focal or global disturbance of cerebral function with symptoms lasting 24 h or longer or leading to death with no apparent cause other than of vascular origin 10 History of stroke at baseline was assessed during the baseline interview and verified by reviewing medical records After enrollment participants were continuously monitored for incident stroke through automated linkage of the study database with files from general practitioners Nursing home physicians’ files and files from general practitioners of participants who moved out of the district were checked on a regular basis as well Additional information was obtained from hospital records Potential strokes were reviewed by research physicians and verified by an experienced stroke neurologist PJK Strokes were further classified as cerebral infarction or intracerebral hemorrhage based on neuroimaging reports If neuroimaging was lacking a stroke was classified as unspecified This classification corresponded with ICD10 codes I61 I63 and I64 Transient ischemic attacks or subarachnoid hemorrhages were not included Participants could contribute person years to the followup for a maximum of 7 years that is from baseline until a firstever stroke occurred or until death or until they reached the age of 95 or if lost to followup until their last health status update when they were known to be free of stroke whichever came first or until they completed 7 years of followup The followup of the 1990 subcohort was complete for 998 of potential person years the followup of the 2000 subcohort for 978 of potential person years

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