Proportion of different subtypes of stroke in China

Incidence of Stroke and Stroke Subtypes in Malmö, Sweden, 1990–2000

BACKGROUND AND PURPOSE

The proportion of immigrants has increased in Sweden markedly during the last decades, as in many other Western countries. Incidence of stroke has increased during this period. However, it is primarily unknown whether incidence of stroke and stroke subtypes in Sweden is related to country of birth.

METHODS

Incidence of first-ever stroke was followed during 10 years in a cohort consisting of all 40- to 89-year-old inhabitants in the city of Malmö, Sweden (n=118,134). Immigrants from 12 different countries were compared with native-born Swedes.

RESULTS

Adjusted for age, sex, marital status, and socioeconomic indicators, the incidence of stroke (all subtypes) was significantly higher among immigrants from former Yugoslavia (relative risk [RR], 1.31; 95% CI, 1.1 to 1.6) and Hungary (RR, 1.33; CI, 1.02 to 1.7). A significantly increased incidence of intracerebral hemorrhage was observed in immigrants from Peoples Republic of China or Vietnam (RR, 4.2; CI, 1.7 to 10.4) and the former Soviet Union (RR, 2.7; CI, 1.01 to 7.3). Immigrants from Finland had a significantly higher incidence of subarachnoid hemorrhage (RR, 2.8; CI, 1.1 to 6.8). A significantly lower incidence of stroke was observed in the group from Romania (RR, 0.14; CI, 0.04 to 0.6). Immigrants from Denmark, Norway, Germany, Chile, Czechoslovakia, and Poland had approximately the same risk as citizens born in Sweden.

CONCLUSIONS

In this urban population from Sweden, there are substantial differences in stroke incidence and stroke subtypes between immigrants from different countries. To what extent this could be accounted for by exposure to biological risk factors remains to be explored.

Fish Consumption and Incidence of Stroke

BACKGROUND AND PURPOSE

Results from observational studies on fish consumption and risk of stroke are inconsistent. We quantitatively assessed the relationship between fish intake and incidence of stroke using a meta-analysis of cohort studies.

METHODS

We searched the Medline and Embase databases (1966 through October 2003) and identified 9 independent cohorts (from 8 studies) that provided a relative risk (RR) and corresponding 95% CI for total or any type of stroke in relation to fish consumption. Pooled RR and 95% CI of stroke were estimated by variance-based meta-analysis.

RESULTS

Compared with those who never consumed fish or ate fish less than once per month, the pooled RRs for total stroke were 0.91 (95% CI, 0.79 to 1.06) for individuals with fish intake 1 to 3 times per month, 0.87 (95% CI, 0.77 to 0.98) for once per week, 0.82 (95% CI, 0.72 to 0.94) for 2 to 4 times per week, and 0.69 (95% CI, 0.54 to 0.88) for > or =5 times per week (P for trend=0.06). In stratified analyses of 3 large cohort studies with data on stroke subtypes, the pooled RRs across 5 categories of fish intake were 1.0, 0.69 (95% CI, 0.48 to 0.99), 0.68 (95% CI, 0.52 to 0.88), 0.66 (95% CI, 0.51 to 0.87), and 0.65 (95% CI, 0.46 to 0.93) for ischemic stroke (P for trend=0.24); and 1.0, 1.47 (95% CI, 0.81 to 2.69), 1.21 (95% CI, 0.78 to 1.85), 0.89 (95% CI, 0.56 to 1.40), and 0.80 (95% CI, 0.44 to 1.47) for hemorrhagic stroke (P for trend=0.31).

CONCLUSIONS

These results suggest that intake of fish is inversely related to risk of stroke, particularly ischemic stroke. Fish consumption as seldom as 1 to 3 times per month may protect against the incidence of ischemic stroke.