Front Neurol: Stroke prevalence and risk factors in 1.4 million adults in China

Cerebral infarction (BI, called ischemic stroke or stroke in Chinese medicine, including cerebral thrombosis, lacunar infarction and cerebral embolism, etc.
, is a brain lesion caused by cerebral blood supply disorders, accounting for 70% of all strokes) is a kind of acute vascular disease, because of the high disability rate, high mortality, high recurrence rate has become a disease of great concern
.

MRI examination of the head can be taken in the direction of each interrupt layer, with high resolution, which is very suitable for examining the central nervous system such as the brain and bone marrow, and can check whether there is an early stroke risk such as asymptomatic cerebral infarction, cerebral atrophy, cerebral hemorrhage, subarachnoid hemorrhage, malformations and lesions, making it one of
the most effective ways to check brain health examination.

Obvious stroke, which is clinically easily identifiable; However, before the onset of cerebral stroke, there are usually no obvious self-conscious symptoms, due to the lack of focal symptoms and signs of the nervous system, the clinical diagnosis rate is low, resulting in the identifiable stroke population is only the tip
of the iceberg.
In brain health examination, CT identified asymptomatic cerebral infarction accounted for 10%~38% of acute ischemic stroke, and asymptomatic cerebral infarction (BI) diagnosed by brain MRI was as high as 47%.

The detection of asymptomatic cerebral infarction indicates that there is a lesion of the cerebrovascular vessels, some brain tissue has been damaged, and if not intervened in time, symptomatic cerebral infarction and vasogenic dementia will occur, resulting in severe limb paralysis and dementia
.

There are few studies on the incidence and risk factors of cerebral infarction (BI) detected by brain magnetic resonance imaging (MRI) in China, and previous studies have been limited
by small sample sizes or only certain geographical areas.
According to the latest epidemiological studies, there has been a clear upward trend of stroke in young age groups in recent years, which can place a huge burden
on the health care system and economy.

Based on this, relying on the network layout of more than 300 cities and more than 600 physical examination centers in Meinian Health and the advantages of hundreds of millions of physical examination data, a brain magnetic resonance imaging (MRI) survey of 1431527 participants from 254 health examination centers in 161 cities in 28 provinces of China was launched to evaluate the prevalence and risk factors of stroke detected by magnetic resonance imaging (MRI).
To provide Chinese scientific researchers and policy makers with the scientific basis
of MRI-defined BI for the early prevention and control of stroke and dementia.

Research methods

This is a multicenter cross-sectional study in which a total of 1,442,518 participants without contraindications to MRI underwent MRI scans
of their brains between January 1, 2018 and December 31, 2018.
For those who have taken more than two health check-ups, only data
from the most recent check-up are included.
We excluded participants younger than 18 years of age, age, sex, and missing data from health screening centres, and 1431527 participants (725261 men and 706266 women) were included in the final analysis
.
MRI defines BI as focal parenchymal lesions ≥3 mm
.
Multivariate logistic regression analysis was employed to assess risk factors
associated with MRI-defined BI.

Research data and analysis

Sample data characteristics

The mean age of study participants was 46.
4 years (SD 12.
4); About three-quarters (75.
2%) were aged 30-59 years and 50.
7% (n = 725,261) were male
.
Nearly half of the participants (49.
2%) were overweight or obese, and 26.
3, 7.
0, and 36.
8% of the study participants had hypertension, diabetes, and dyslipidemia
, respectively.
Participants with MRI-defined BI were more likely to be older men with a higher prevalence of overweight or obesity, hypertension, diabetes, and dyslipidemia than participants without MRI-defined BI (all P

Table 1 Characteristics of cerebral infarction status of study participants as defined by MRI

MRI-defined prevalence of cerebral infarction

Of the 1,431,527 study participants, 100,245 (7.
00%; 95% CI: 6.
96–7.
05%) was identified as an MRI-defined BI.

The mean age of BI participants defined by MRI was 58.
7 years (SD 10.
4), and men and women were similar: 58.
7 years (SD 10.
6) for men and 58.
7 years for women (SD 10.
2).

The crude incidence of lacunar infarction was 5.
57% (n = 79,724, 95% CI: 5.
53–5.
61%) and 1.
43% (n=20,521, 95% CI: 1.
41–1.
45%)
.
The age- and sex-standardized prevalence of MRI-defined BI, lacunar infarction, and non-lacunar infarction was 5.
79% (95% CI: 5.
75–5.
83%), 4.
56% (95% CI: 4.
52–4.
60%), and 1.
23% (95% CI: 1.
21–1.
25%), respectively (Table 2).

Table 2 Standardized prevalence of cerebral infarction in the Chinese health examination population in 2018
.

Multivariate analysis of associations between cerebral infarctions

The sex-standardized prevalence of MRI-defined BI was positively correlated with age, with a prevalence of 0.
46% for 18-29 years of age, 0.
98% for 30-39 years of age, 30.
30% for 70-79 years of age, and 37.
33%
for 80 years of age.
There was a particularly significant increase in people aged 60 years or older (Table 2).

Both lacunar infarction and non-lacunar infarction tended to
increase significantly with age.
Male (6.
30%; The prevalence of age-standardised MRI-defined BI was significantly higher in 95% CI: 6.
24–6.
37% than in women (5.
28%; 95%CI：5.
21–5.
34%； P < 0.
001), and in all age groups, the age-specific prevalence of MRI-defined BI was significantly higher in men than in women (Table 2).

Fig.
1 Standardized incidence
of cerebral infarction in 28 provinces of China.
The statistics mentioned here do not include Heilongjiang, Ningxia, Tibet, Hong Kong, Macau and Taiwan

Figure 1 shows that among the seven geographic regions, the highest standardized prevalence of BI defined by MRI was in the Northwest (8.
34%, 95% CI: 8.
17–8.
51%); This was followed by the Northeast (8.
02%, 95% CI: 7.
87–8.
18%) and the lowest in the Southwest (4.
02%, 95% CI: 3.
92–4.
13%)
.
The highest standardised prevalence of lacunar infarction also occurred in the Northwest (7.
33%, 95% CI: 7.
18–7.
50%); This was followed by the Northeast (7.
23%, 95% CI: 7.
08–7.
38%) and the lowest in the Southwest (3.
28%, 95% CI: 3.
19–3.
38%)
.
The highest standardised prevalence of nonlacunar infarction was in the north (2.
63%, 95% CI: 2.
53–2.
73%); followed by the Central Region (1.
74%, 95% CI: 1.
69–1.
80%); The prevalence was lowest in the south (0.
61%, 95% CI: 0.
56–0.
67%)
.

Other multivariate analysis results

In multivariate-adjusted analyses, men (OR 1.
17; 95% CI 1.
15–1.
19), older age (OR 2.
33; 95% CI 2.
31–2.
35 per additional 10 years of age), overweight (OR 1.
12; 95% CI 1.
10–1.
14), or obese (OR 1.
18; 95% CI 1.
16–1.
21), hypertension (OR 1.
80; 95% CI 1.
77–1.
83), and diabetes (OR 1.
24; 95% CI 1.
21–1.
26) and dyslipidemia (OR 1.
07; 95% CI 1.
05–1.
08) were significantly associated with a high risk of MRI-defined BI (P < 0.
05; Table 3).

These correlations are also significant
in lacunar infarction and non-lacunar infarction, respectively.

Research results and discussion

Among the 1.
4 million participants who underwent health screenings across China, we found an age- and sex-normalized frequency of 5.
79% (95% CI, 5.
75–5.
83%) for MRI-defined BI in 2018, with the majority of these infarcts being lacunar
infarctions.
We observed that the frequency of sex normalization of MRI-defined BI correlated with
increasing age.
In our study, sex differences and geographic differences in MRI-defined BI frequencies were also observed, with higher
frequencies in men and northern regions.
Overweight/obesity, hypertension, diabetes, and dyslipidemia were significantly positively associated
with the risk of MRI-defined BI.

To our knowledge, this study is the largest investigation of the distribution and risk factors for MRI to detect BI; Second, in our study, the wide age range of participants allowed us to assess the burden of MRI-defined BI in younger adults, which was not feasible in previous studies that focused primarily on older participants; In addition, our study is the first to assess the geographic differences in MRI-defined BI across the country, which provides important information for allocating medical resources from a multi-layered geographic perspective to reduce the burden
of MRI-defined BI.
The results of this study provide solid evidence
for the enormous burden of MRI-defined BI in the health screening population.