The Isfahan cohort study: rationale, methods and main findings.

A 10-year longitudinal population-based study, entitled the Isfahan Cohort Study (ICS) is being conducted. The ICS commenced in 2001, recruiting individuals aged 35+ living in urban and rural areas of three counties in central Iran, to determine the individual and combined impact of various risk factors on the incidence of cardiovascular events. After 24379 person-years of follow-up with a median follow-up of 4.8 years, we documented 219 incident cases of ischemic heart disease (IHD) (125 in men and 94 in women) and 57 incident cases of stroke (28 in men and 29 in women). The absolute risk of IHD was 8.9 (7.8-10.2) per 1000 person-years for all participants, 10.6 (8.8-12.5) per 1000 person-years for men and 7.4 (6.0-9.0) per 1000 person-years for women. The respective risk of ischemic stroke was 2.3 (1.7-3.0), 2.3 (1.6-3.3) and 2.3 (1.5-3.2) per 1000 person-years. The risk of IHD was approximately 3.5-fold higher in the presence of hypertension, followed by diabetes mellitus and hypercholesterolemia with near 2.5- and twofold higher risk, respectively. This cohort provides confirmatory evidence of the ethnic differences in the magnitude of the impact of various risk factors on cardiovascular events. The differences may be due to varying absolute risk levels among populations and the existing ethnic disparities for using western risk equations to local requirements.

Standard method for developing stroke registers in low-income and middle-income countries: experiences from a feasibility study of a stepwise approach to stroke surveillance (STEPS Stroke).

BACKGROUND: Stroke is a leading global cause of death, with an estimated 5.8 million fatal events in 2005, two-thirds of which happened in low-income and middle-income countries. In these regions, epidemiological methods to establish hospital-based stroke registers for clinical audit or studies to estimate incidence are scarce. Our aim was to ascertain whether stroke registers could be set up in geographically diverse populations in low-income and middle-income countries, using standardised data-collection manuals and methods, before recommending their wider use. METHODS: WHO's stepwise approach to stroke surveillance (STEPS Stroke) offers an entry point for countries to register stroke patients in health-information systems. The methods proposed in this strategy were tested in a feasibility study, which focused on hospitalised stroke patients in nine different surveillance sites located in five low-income and middle-income countries. Data collection was for a median of 12 months. Observed differences between men and women were adjusted for age and surveillance site with logistic-regression analyses. FINDINGS: A total of 5557 stroke patients were registered; 91 people whose age was missing or younger than 15 years were excluded from the analyses. Mean age was 64.2 years (SD 14.6), and 2484 (45%) participants were women. Ischaemic stroke accounted for about two-thirds of events. Half of all patients were hospitalised the same day. Stroke subtype was verified in 4913 (90%) participants by diagnostic techniques. Women had lower odds of verification of stroke subtype compared with men after adjustment for age and surveillance site (odds ratio 0.69 [95% CI 0.56-0.86]; p=0.0006). INTERPRETATION: STEPS Stroke can be used in diverse populations to provide data in a standardised manner in countries with little or no previous records of stroke. Future studies should concentrate on expansion beyond hospital case series by adding information for stroke patients treated outside the hospital, linked to census data for the source population from which the cases come.