Unconventional association between risk factors and knowledge of stroke among cerebrovascular disease survivors in China: A cross-sectional community-based study (FAST-RIGHT) CURRENT STATUS: POSTED

Background: Cerebrovascular disease (CVD) survivors are at a risk of recurrent strokes, and early correct response to stroke is crucial to promote access to effective reperfusion therapy. This study aimed to investigate whether there is an association between increased risk factors and the intent to call emergency medical services (EMS) among CVD survivors. Methods: A cross-sectional community-based study was conducted from January 2017 to May 2017, including 187 723 adults (age ≥ 40 years) across 69 administrative areas in China. A CVD survivor population of 6290 was analyzed. Multivariable logistic regression models were used to identify the association between the number of modifiable risk factors and stroke recognition and EMS calling, respectively. Results: The estimated stroke recognition rate in CVD survivors with 0, 1-2, and 3-7 modifiable risk factors was 84.7% (321/379), 84.4% (2346/2780), and 85.6% (2673/3123), respectively. The rate of calling EMS in the 0, 1-2, and 3-7 modifiable risk factor groups was 66.0% (250/379), 62.7% (1744/2780), and 67.8% (2117/3123), respectively. The prevalence of cardiovascular diseases was higher among CVD survivors than the non-CVD population. The CVD survivors’ knowledge of recognizing stroke and intent to call EMS did not improve with an increasing number of modifiable risk factors, even after adjustment for multiple sociodemographic factors. Conclusions: Despite being at a higher risk of recurrent stroke, Chinese CVD survivors showed poor knowledge of stroke, and their intent to call EMS did not improve with stroke risk. Special, targeted, and enhanced secondary stroke prevention education is needed for CVD survivors.


Introduction
In China, as in many countries, stroke is a major health challenge, with an increasing number of stroke-related deaths and disabilities [1][2][3][4]. Reperfusion therapy with intravenous alteplase, when administered to patients soon after symptom onset, can improve the outcomes of acute ischemic stroke (AIS). However, in clinical settings, less than 2% of AIS patients receive reperfusion therapy with alteplase in China, mainly due to pre-hospital delays from poor knowledge of stroke [5,6].
Emergency medical services (EMS) usage accelerates presentation to the hospital, but a very low proportion of AIS patients use EMS in China [6][7][8][9]. Survivors of CVD are prone to a recurrent stroke, which is more severe and disabling [10][11][12]. However, in our previous report on FAST-RIGHT, a substantial number of CVD survivors (34.6%) did not call EMS [13]. and the details on stroke recognition and responses among CVD survivors remain unclear. In China, common vascular risk factors such as hypertension, diabetes and dyslipidemia are not well adequately managed [14][15][16], and many of them probably do not know that their risk factors relate to stroke, which depends on stroke education [17]. The intent to calling EMS seems more important to patients with higher stroke risk. Therefore, based on the FAST-RIGHT study, we aimed to determine the characteristics of CVD survivors, and whether the intent to call EMS increased with the number of modifiable risk factors. We also examined other potential confounders associated with stroke recognition and calling EMS.

Methods
Data were obtained from the FAST-RIGHT study, which is part of the China National Stroke Screening Survey (CNSSS), and included 69 administrative areas between January 2017 and May 2017. More details on the CNSSS are outlined elsewhere [13,18], and can also be found on the website of the National Health Commission [19]. The CNSSS was a cross-sectional community-based survey with a 2stage stratified sampling framework based on county-level demographic data. In the FAST-RIGHT study, residents aged 40 years and older were screened by trained research staff using a standard face-to-face questionnaire that covered information about sociodemographic, medical, and family history, lifestyle factors, and four specific questions regarding stroke awareness (See Supplementary Appendix 2, Additional File 1). Commencement of provision of stroke education was also recommended after completing the questionnaire survey. All screening data were transferred from questionnaires to an electronic database and checked centrally for completeness and errors by an experienced data manager. The FAST-RIGHT study was approved by the central ethics committee of Peking Union Medical College Hospital (the principal study center), and all participants provided written informed consent.

Explanatory and Outcome Variables
Recognition of stroke symptoms was defined as a participant's unprovoked awareness of "facial droop," "arm weakness," and "speech disturbances" (slurred speech, or word-finding difficulties) [20].
Calling EMS immediately after the onset of any of these symptoms was regarded as the correct action in response to a stroke. A reported history of stroke was confirmed by a neurologist or physician, who applied standard diagnostic criteria with any available brain neuroimaging data. The modifiable risk factors included hypertension, diabetes, dyslipidemia, overweight and obesity (BMI=24-50), atrial fibrillation (AF)/valvular heart disease, smoking (including current, former, and passive smoking), and

Statistical Analyses
The stroke recognition rate (SRR) and correct action rate (CAR) were determined and presented as rates with 95% confidence intervals (CI) on the basis of specific subgroups defined by age, sex, site, region, education level, and annual income among CVD survivors. The association between the increased number of modifiable risk factors and stroke recognition, as well as that between the increased number of risk factors and calling EMS were analyzed using multivariable logistic regression. Comparisons of sociodemographic and cardiovascular factors between the CVD survivor and non-CVD groups were performed within the whole group. A standard two-sided P value (< 0.05) was considered statistically significant. All analyses were performed using SAS version 9.3.

Results
Of the 187,723 residents screened for eligibility, 6,290 were CVD survivors and were included in our analysis. CVD survivors with more risk factors had a higher CAR, but had a similar SRR to those having a single risk factor. The estimated SRR and CAR varied across regions and socioeconomic statuses ( Table 1). Across all the different subgroups, CAR was 5.3%-29.3% lower than SRR. Among those that recognized the onset of a stroke, only 67.9% intended to call EMS (See Supplementary   Table S2, Additional File 1).
[ Table 1] Compared to the non-CVD population, CVD survivors made up significantly larger proportions of the elderly and obese patients, as well as participants with lower socioeconomic status (See Supplementary Figure S1-S4, Additional File 1). A markedly higher prevalence of cardiovascular risk factors was observed in CVD survivors ( Figure 1). Figure S5 shows that CVD survivors had fewer avenues to learn about stroke.

Discussion
Our study shows that the knowledge of identifying stroke onset and intent to call EMS in Chinese CVD survivors were very poor and did not improve with increasing stroke risk. Fortunately, the CVD survivors were slightly more aware of the correct stroke response than the non-CVD population [13].
The rate of intent to call EMS (65.4%) [13] was almost similar to those previously reported in China [21] (58.5%), the United States [22] (62.9%), and Japan [23] (81.2%), but was markedly higher than the actual EMS usage rate in China (15.4%-23.1%) [6,8,9]. However, even in the CVD survivors with more than 3 risk factors, one-third of them would not call EMS at the onset of a recurrent stroke.
CVD survivors are liable to experience a recurrent stroke, which is usually more disabling and costly than the first episode [10,11,24]. Higher prevalence of cardiovascular risk factors among CVD survivors was reported in our study, which accounted for the majority of cases of stroke onset [25].
Among the CVD survivors, multiple risk factors indicated a higher risk of recurrent stroke [25], which seems to be even higher in China due to poor control of these factors [26][27][28][29]. Unfortunately, in our study, higher stroke risk did not increase their intent to call EMS, which may delay access to reperfusion therapy [6,9,30]. CVD survivors probably failed to regard underlying diseases as risk factors of stroke [17,31,32], and did not fully understand the danger of cardiovascular risk factors, and were unaware of their situation [17], probably due to poor education on secondary stroke prevention. Therefore, comprehensive education about risk factors, recurrent stroke recognition, and calling EMS is needed to reinforce secondary prevention of stroke [31].
In contrast to results from the entire population, the odds of calling EMS among the CVD survivors depended only on a few factors, such as the region and annual income [13]. Moreover, contrary to the results from the entire group and previous studies [13,33], even highly educated CVD survivors did not perform better at recognizing stroke onset and calling EMS. Therefore, there are underlying factors other than lack of stroke education that remain unclear and require further study. This emphasizes the need to revise our previous programs to educate CVD survivors differently from the non-CVD population. In addition, doctors should optimize secondary preventive stroke-education programs to educate patients about the appropriate response to stroke onset. Moreover, the limited number of associated factors that affect the odds of calling EMS among CVD survivors imply that targeted stroke-education programs can be more efficiently designed and conducted for CVD survivors than for the non-CVD population [13].
Low education, low income, rural location, and advanced age were more common among CVD survivors, which indicated a lower equity of needs and resource allocation to EMS [34,35] and a poor capacity to curb the stroke burden [36,37]. Additionally, our study demonstrated that having > 4 avenues for gaining knowledge on stroke was associated with calling EMS, indicating that the CVD survivors were not sensitive to solitary education campaigns, while multiple avenues showed synergistic effects [23]. However, with the availability of point-to-point functions, Internet-related avenues appear to be more appropriate to educate specific groups, although the Internet usage rate is extremely low among Chinese CVD survivors [23,32,38]. Finally, since CVD survivors face extremely high prevalence of risk factors, it is better to make them recognize that good control of these modifiable risk factors can reduce stroke risk [25], and that timely and proper response to stroke onset is critical to improving the outcome [33]. Thus, we should consider these unique and unfavorable points when launching education programs for Chinese CVD survivors.
The limitations of this study include the bias due to the multistage nonrandom sampling design and selection from CNSSS, although screening sites in urban and rural areas were selected in a 1:1 ratio [18]. Moreover, even though we investigated the intent to call EMS, the respondents' actual responses to stroke remain unclear and may be overstated [22,39]. Finally, despite the stroke risk factors being extensive, we only selected seven modifiable risk factors to assess the risk for recurrent stroke. Therefore, the influence of the other factors remained unknown. For example, the information on intracranial arterial stenosis was not available in our study.
In conclusion, this community-based study found that stroke recognition and intent to call EMS in response to stroke-related symptoms was low among Chinese CVD survivors, and did not improve with increasing number of risk factors. Additionally, CVD survivors were characterized by low socioeconomic status and a higher prevalence of stroke risk factors. The findings indicate the need for targeted and enhanced secondary preventive stroke-education programs for CVD survivors that focus on the control of modifiable risk factors, stroke recognition, and correct response to stroke.

Declarations
Availability of data and materials The data sets in this study are available from the corresponding author on reasonable request.
Authors' contribution BP, LW, and LYC designed the study. SL, CY, GS, and BP analyzed the data. CG finished data collection and management. SL wrote the paper. LYC, BP, and CA revised the paper.

Supplementary Files
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Additional file 1.pdf