Background: Chinese populations have been reported to have a higher stroke
incidence as well as different stroke epidemiology compared with white populations.
However, reliable comparisons have been precluded by a lack of methodologically
robust studies. I aimed to systematically evaluate the incidence of stroke, the
distribution of its main types/subtypes, and risk factor distributions among stroke
types/subtypes in Chinese, and to compare these with data from white populations.
Methods: I performed a series of systematic reviews and meta-analyses of studies
conducted since 1990 which had data on (1) incidence of stroke, (2) pathological
types of stroke or ischaemic stroke subtypes, and (3) frequency of risk factors among
pathological types of stroke or ischaemic stroke (IS) subtypes in Chinese populations,
and in white populations for comparison. I calculated age-standardized stroke
incidence and the proportions of each pathological type and ischaemic subtype. For
each risk factor, I calculated study-specific and pooled odds ratios (ORs) using a
random effects model for intracerebral haemorrhage (ICH) versus IS, for each IS
subtype versus other subtypes, and for overall IS patients, comparing findings for
Chinese versus Whites.
In addition, I conducted individual patient analyses of data from the National Taiwan
University Hospital (NTUH) Stroke Registry, which consecutively recruited 6675
acute stroke patients from 2006-2011, comparing risk factor profiles among stroke
types and subtypes and using logistic regression to adjust for potential confounding
factors.
Results: From my systematic reviews, I found a younger onset of stroke, a slightly
higher overall stroke incidence and higher proportion of ICH in Chinese versus white
populations. Although the overall proportion of lacunar infarct appeared higher in
Chinese from hospital-based studies than white populations, confirming the different
distributions of ischaemic subtypes will need further comparable population-based
studies.
In my meta-analyses comparing risk factors for ICH versus IS, in Chinese - but not
Whites – hypertension (HTN) and alcohol intake were significantly more frequent,
while mean age was lower in ICH than IS. In IS, the overall prevalence of
hypertension, diabetes, smoking, and alcohol intake were similar between Chinese
and white IS patients, whereas hypercholesterolaemia, ischaemic heart disease (IHD)
and atrial fibrillation (AF) were less common in Chinese IS patients. As for IS
subtypes, the relative frequencies of risk factors were mostly qualitatively similar
(although different in size) in Chinese and white populations. Compared with other
ischaemic subtypes: large artery atherosclerosis (LAA) strokes were associated with
diabetes; cardioembolic (CE) strokes were associated with AF and IHD; small vessel
disease (SVD) strokes or lacunar strokes were associated with hypertension and
diabetes.
Analyses of NTUH individual patient data showed that HTN and alcohol intake were
independent risk factors for ICH versus IS in a Chinese population in Taiwan,
regardless of age, sex, or other risk factors. The results were consistent with my
previous risk factor meta-analyses for ICH versus IS. In IS analyses, the prevalence
of hypertension, diabetes, AF, and hyperlipidaemia in overall IS patients based in
Taiwan were higher than the pooled results in my risk factor meta-analysis for IS for
all Chinese populations including mainland China. In terms of risk factor
associations with IS subtypes, the findings after controlling for potential confounders
were mostly close to my previous meta-analysis results with the exception of
stronger associations of hypertension and diabetes with SVD (lacunar) strokes.
Conclusion: I have shown a younger onset of stroke, a higher overall stroke
incidence, an around twofold higher proportion of ICH and different distribution of
IS subtypes, as well as some differences in risk factor distributions among
pathological types of stroke and IS subtypes in Chinese compared with white
populations. My results help to inform us of different stroke mechanisms in different
populations, to guide further well-designed research in this area, and to direct better
strategies for stroke prevention in Chinese populations