Relationship between allergic asthma and cerebrovascular accident: allergic asthma can increase recurrence of stroke

Introduction

Asthma is a common, chronic respiratory disease which can result in persistent or episodic symptoms and limitation of airflow, and airway wall thickening [1]. The pathophysiology of the asthma is heterogeneous and complex, including different interactions happening at several scales, from genes to organs [2, 3]. Asthma causes different symptoms such as chest tightness, wheezing, cough, impaired lung function, acute asthma attack, and disturbs daily life [4]. About 300 million people suffer from asthma internationally, and the prevalence of asthma is increasing [5, 6]. Approximately up to 10% of asthma patients are reported to suffer from severe asthma [3]. This patient group has poor disease control and recurrent exacerbations in spite of treatment with mixed inhaled medication therapy [7]. It has been observed that there are other co-morbidities in asthma patients and asthma can increase the severity of those diseases or those diseases can increase the severity of asthma in patients and based on the severity of asthma, the prevalence of these diseases can increase [8]. It was confirmed that stroke can be more common in patients with respiratory diseases. So, there may be a marked interaction between asthma and stroke as asthma can be an independent risk factor for stroke, and severity of asthma exhibits a linear response of stroke progress [9, 10]. This evidence represents the basis for expansion of neuro-respiratory disorders, which emphasizes the significance of the interconnection between the central nervous system (CNS) and pulmonary systems for enhancing the management of patients [11, 12]. As the second leading cause of death stroke is the foremost cause of disability, with approximately 11% of all deaths. Stroke incidence is estimated to be 0.2% of the population yearly, with the mortality rate of 16.6% within the 1^st month of ischemic stroke and nearly 50% of stroke patients suffer from disability [13]. Cerebrovascular disease mentions vasculature brain disorders which affect the blood stream of the related tissues. For better understanding of this disorder, the pathology of the cerebral vessels, and also the brain parenchyma and risk factors which may affect these structures must be known [14]. Stroke may affect life expectancy, emotion, mentality, and stroke-related disability makes survivors reduce their employability [15]. Approximately 34% of worldwide healthcare expenditure is related to the stroke. In recent decades in people aged under 65, the incidence of stroke has increased. Now, the risk of stroke in younger people has also been considered [16]. Therefore, scientists try to discover new risk factors for stroke. As mentioned asthma may be a possible risk factor for stroke. Chronic inflammation plays a significant role in stroke development [17]. Also, asthma as an inflammatory disease can play an important role in the possibility of stroke [18]. Previous studies reported the relationship between asthma and stroke, because the inflammatory nature of asthma can cause stroke and this has been documented in the mentioned research studies [19]. And now asthma can be introduced as an independent risk factor in the occurrence of stroke, although there are not enough findings in this regard.

Aim

Considering the importance of the emergence of possible risk factors for the occurrence of stroke and according to past research studies on the role of asthma in the development of stroke, the aim of the current study is to evaluate the relationship between allergic asthma and cerebrovascular accident in two different parts: the effect of stroke on pulmonary function (PF) of asthma patients and also the relationship of asthma and incidence of recurrent stroke.

Material and methods

Results

The average age of the patients in the three groups shows that there is no significant difference between the ages of the patients (p = 0.28). Also, the average weight (p = 0.55), height (p = 0.45) and BMI (p = 0.44) of the patients of all three groups did not show any significant difference. Moreover, 50% of patients in each group were female (Table 1).

Discussion

The present study showed that after stroke in asthmatic patients, pulmonary function was significantly reduced and compared to asthmatic non-stroke patients, all FVC, FEV1, FEV1/FVC, MIP, MEP and 6MWT were significantly reduced. Also, compared to non-asthmatic stroke patients, all of above factors have been significantly decreased in asthmatic stroke patients. But these findings have not been clear in past studies, because in some studies, a significant difference has been reported between the occurrence of stroke and a decrease in pulmonary function, and in some other studies, this difference was not significant, so this issue is still controversial. After stroke respiratory muscles become weaker in addition to chest muscles, which decreases exercise capacity and produces problems in performing daily life activities [20, 21]. Previous research studies showed that decreased respiratory muscle activity may reduce core stability, which is essential for normal balance and mobility [22, 23]. Lista-Paz et al. showed that stroke patients had significantly reduced lung volumes, also 6MWD was reported to be weakly correlated with inspiratory reserve volume and peak inspiratory flow [24]. In another study the authors reported lower values of MIP and MEP in survivors and a positive correlation between 6MWT and MIP [25]. Also, Ezeugwu et al. reported that compared to the controls, the stroke patients had significantly reduced values for FEV1, FVC and PEF [26]. The results of Jandt et al. also confirm a reduction in MEP and MIP in stroke patients, and showed a positive significant correlation between MEP and trunk control [27].

Another finding of the present study is that the prevalence of recurrent stroke in asthmatic stroke patients is higher than in stroke patients without asthma. This finding has been less investigated in other studies and has had conflicting results and is still controversial. The chronic inflammatory nature of asthma speeds up the atherosclerosis process, which may develop stroke progress [28]. Asthma and stroke have various common risk factors, as well as/and so have aging, air pollution, smoking, and stress. Therefore, the relationship between asthma and stroke, affected by confounding factors. Previous research studies showed that asthma was an independent risk factor for stroke. Asthma induced endothelial damage, enhanced progression of atherosclerosis, and initiated thrombosis, by reducing lung function and hypoxemia [29, 30]. Allergens can cause activation of inflammatory pathways in the asthmatic patient’s lungs, which is aggravated by the platelets pro-inflammatory effects and reduce cyto-protective response [31]. Asthma can exacerbate thrombosis of cerebral vessels and elevate the vulnerability of the cerebral vessels, thus cause a stroke risk in patients. We found that stroke recurrence was 32.5% in the asthma stroke group and 12.5% in the non-asthma stroke group, which was significantly higher in the asthma stroke group (p = 0.001). In contrast with our findings, Kim et al. [32] showed that none of the asthma patients reported elevated HRs for stroke and asthma did not promote the risk of stroke. But in line with the current study, Cepelis et al. [33] by evaluating 58,712 adult patients reported that active asthma was associated with a modest elevated relative risk of stroke in smokers and also in males. Also, Onufrak et al. [34] showed that females with adult asthma experienced a 2-fold increase in the risk of stroke in the America. Moreover, Chung et al. in a cohort study using health claim codes showed a 1.37-fold higher risk of stroke in asthma patients [35]. Another study by Iribarren et al. [36] showed that asthma is associated with a 1.2-fold hazard of stroke for adults. Also Wen et al. [37] reported in a meta-analysis study which included 5 articles with 524,637 participants, that asthma is associated with a significantly elevated risk of stroke. Finally, the results of the present study and the review of other studies show that asthma is an independent risk factor for stroke in patients.

Conclusions

The results of the present study showed that in asthmatic people, stroke can significantly reduce lung function by decreasing FVC, FEV1, and FEV1/FVC. Also MIP and MEP are reduced, which shows a decrease of respiratory muscle function and 6MWT were significantly as test for exercise capacity, decrease in asthmatic patients after stroke, likewise asthma can increase the risk of recurrence of stroke in asthmatic stroke patients as an independent risk factor.