Insights Into Pediatric Asthma: A Population Study From Alto Minho Health Center

Background Asthma represents one of the most common diseases in childhood, with a prevalence ranging between 9% and 13% in Portugal. Therefore, it holds significant importance in pediatric health. While existing studies have shed light on asthma in the Portuguese population, they have predominantly concentrated on urban centers, with the population of Alto Minho remaining underrepresented in the literature. This study aims to understand the main factors of exposure, exacerbation, and the most prevalent allergens in a pediatric sample from the Alto Minho Local Health Unit, Portugal. Methodology A retrospective cohort study was conducted among 239 pediatric asthma patients aged between five and 18 years at the Alto Minho Health Center. Data on demographics, clinical information, family history, environmental exposures, exacerbating factors, and prick test results were analyzed. Results Of the 239 patients, 64.44% were male and 35.56% were female. The majority of the sample exhibited a normal body mass index (82.17%) and a family history of atopy (66.67%). Noteworthy patterns emerged in comorbidities, notably an increased association with allergic rhinitis, the most frequent concomitant atopic pathology (79.50%), followed by atopic dermatitis (27.61%) and food allergy (10.88%). Sensitization to dust mites, particularly Dermatophagoides pteronyssinus, was widespread among the participants. Environmental exposures were marked by significant factors such as proximity to plants and trees, soft toys, and living in rural areas. Exacerbating factors included common triggers such as exercise, seasonal variations, and even laughter. Statistically significant associations were found between atopic comorbidities, exacerbation factors, exposure factors, and prick test results. Conclusions Our findings align with global trends, emphasizing the prevalence of atopic pathologies in pediatric asthma. Sensitization patterns and environmental exposures are indicative of regional influences. Study limitations include sample size and data standardization issues. Despite these limitations, the study significantly contributes to understanding pediatric asthma in Alto Minho, offering valuable insights for prompt diagnosis and targeted treatments.


Introduction
Asthma is a complex and heterogeneous disease, characterized by chronic airway inflammation.It is characterized by respiratory symptoms, including wheezing, dyspnea, chest tightness, and cough, which can vary in frequency and severity and can be associated with variable expiratory airflow limitation [1].
Asthma is a significant health problem worldwide and is one of the most common chronic diseases in childhood, with prevalence rates ranging from 1% to 18% across different countries [2].In Portugal, data from the International Study of Asthma and Allergies in Childhood revealed that the prevalence of asthma in children aged six to seven years was 13%, while in teenagers aged 13 to 14 years, it ranged from 9% in 1995 to 12% in 2002 [3].
Numerous studies have demonstrated a notable association between childhood asthma and atopic diseases, including allergic rhinitis (AR), atopic dermatitis (AD), and food allergies (FAs) [3,4].It is known that over 80% of asthmatics have comorbid AR [5].Asthma, AR, and AD are known as the atopic triad and share immunological mechanisms [6].
Several risk factors have been identified, such as a personal history of AR, AD, or FAs; a family background of allergic diseases; and a maternal history of asthma and/or rhinitis [1,3,6,7,8].
The main hypothesis that is currently proposed to explain the onset of allergic diseases is an epithelial barrier defect.Thus, the atopic march could correspond to epithelial dysfunction, self-sustained by a secondary allergenic sensitization, explaining the transition from AD to allergic asthma.Furthermore, AD severity appears to be a risk factor for associated FAs.Results from population-based, birth, and patient cohorts have shown that early-onset and severe AD, male gender, parental history of asthma, and early and multiple sensitizations are risk factors leading to atopic march and the development of asthma [9].
A Portuguese study revealed that in individuals who experience both AR and asthma, the most prevalent allergens are pollens (wild and cultivated grasses) along with dust mites (Dermatophagoides pteronyssinus, Lepidoglyphus destructor, and Dermatophagoides farinae) [10].
As delineated in the literature, FA is a firmly established risk factor in the onset of allergic asthma among children.Studies have indicated that children with FAs are potentially twice as likely to develop asthma [1,7].
Triggers of asthma exacerbations mostly include airborne allergens, respiratory infections, and occupational substances.Other factors that can influence asthma include tobacco smoke, gastroesophageal reflux disease, environmental pollutants, some medications such as β-blockers and non-steroidal anti-inflammatory drugs, and food additives.Irritants such as exercise in cold air, emotions, stress, strong odors or other respiratory irritants, and temperature changes can trigger bronchoconstriction.Animal dander and house dust mites have been shown not only to contribute to the development of asthma but also to induce exacerbations [11].
The burden of asthma on pediatric health in Portugal deserves considerable attention due to its significant prevalence.However, a knowledge gap exists regarding the rural context, with most studies focusing on urban centers.Thereby, the population of Alto Minho remains underrepresented in the literature, warranting a comprehensive understanding to facilitate tailored medical interventions for preventive measures, diagnoses, and ongoing care among the pediatric demographic of this region.
The main aim of this study is to comprehensively characterize a sample of children and adolescents diagnosed with asthma under the care of specialized pediatric practitioners in Alto Minho.Through this effort, our aim is twofold: first, to enhance the understanding of potential exposure and exacerbating factors specific to this population, thus bridging a crucial gap in the existing literature.Second, we seek to identify the most prevalent allergens within this sample, enriching our insights into this demographic.

Ethical considerations
This study was conducted following the Declaration of Helsinki (59th Amendment) and was approved by the relevant local ethics review board from the Health Center of Alto Minho, Portugal (approval number: 37/2023).The anonymity and confidentiality of the study participants were guaranteed throughout all research activities.

Characterization of participants
A retrospective cohort study was conducted among patients who were under follow-up on December 31, 2020, in the pediatric unit of Unidade Local de Saúde do Alto Minho, located in north Portugal.This study included information from patients aged between five (the ability to diagnose asthma in preschool children is controversial) and 18 years with a confirmed diagnosis of asthma [12].Children who did not meet the inclusion criteria were excluded.
The data used in this study encompassed the gender and age of children and adolescents, clinical information such as body mass index (BMI) and other atopic diseases (AR, AD, and FA), family history of first and second-degree relatives with atopic diseases, exposure factors (e.g., animals, pollens, smoke, humidity, rugs and curtains, urban or rural residential area), exacerbating factors (e.g., laughter, physical exercise, cold, season, smoke), and skin prick test results.Taking into account that it can be considered a risk factor, BMI was collected from the first appointment registers.Following the established criteria, 239 patients were selected (Figure 1).

Statistical analysis
Descriptive statistics of clinical and demographic data were performed using SPSS Statistics version 27 (IBM Corp., Armonk, NY, United States).Data were presented as frequency and percentage for categorical variables and as mean, standard deviation, median, and minimum/maximum values for numerical variables, both for the total sample and specific subgroups.As the data did not follow a normal distribution, nonparametric tests, such as the chi-square test, were applied.Results were considered statistically significant when the p-value was less than 0.05.

Demographic and body mass index analysis
A total of 239 patients diagnosed with asthma were enrolled in the present study.Concerning sex distribution, the sample comprised 154 (64.44%) males, exhibiting a mean age of 13.60 years (SD = 3.99), and 85 (35.56%) females, with a mean age of 13.65 years (SD = 4.13).Figure 2 delineates the age distribution of patients, at the time of data collection, stratified by gender.Due to heterogeneity in registration, BMI data were successfully obtained for a subset of 157 participants on   Overall, 17 (10.87%)children/adolescents were obese, and 11 (7.01%) were overweight; however, the majority, 129 (82.17%) children/adolescents were of normal weight.The average percentile of the sample was 68.68 (SD = 27.97) and was located within the range of normal weight.For more details, see Table 1.

Atopic diseases, family history, and contextual factors
Of the 239 children and/or adolescents with asthma, 221 (92.47%) had comorbidity with another atopic condition (i.e., AR, AD, and FA).Here, data are described for those with asthma and only one other condition, those with asthma and two other associated conditions, and, finally, those with AR, AD, and FA combined with a previous diagnosis of asthma.

Discussion
This study aimed to characterize a pediatric sample of 239 pediatric patients diagnosed with asthma in Alto Minho.Gender distribution matched with other international studies, which reported a predominance of allergic pathology in males in the pediatric age group [13].
BMI might be one of the potential risk factors for developing asthma, but the evidence is controversial [5].
Although some studies have shown a significant relationship between BMI (obesity/overweight) and asthma among children and adolescents, according to Inquérito Nacional de Controlo de Asma [14], the Portuguese national survey of asthma control, poorer symptom control was observed in the overweight and obese groups, but the majority of patients had a normal BMI.Our results showed that the majority of the sample was normal weight, which aligns with the results of the national study.Additionally, no significant age or BMI differences were found between genders.However, more robust future studies are needed to draw conclusions.
In line with global research, there is a high prevalence of other atopic pathologies in children/adolescents with asthma in this geographical region [13,15].Most individuals also had a diagnosis of AR.In addition, the atopic triad was present in 22.60% (n = 54) of the sample studied.Of the children and adolescents reporting atopic diseases, most had a family history of atopy.
The prevalence of sensitization to dust mites was found to be high, followed by pollens, which is consistent with studies indicating that dust mites and pollen allergies are the most common causes of respiratory allergic diseases in Portugal and other European countries [15].
The most prevalent mite in the study was Dermatophagoides pteronyssinus, and this prevalence is related to the fact that this species is the most frequent in homes in the northern coastal area of the country, as shown on the acarological map of Portugal [15].Although the Dermatophagoides farinae mite has a low presence in the northern coastal region of Portugal, in this study, it was the second most prevalent mite causing atopic disease.The third most prevalent mite in this study was Lepidoglyphus destructor, which aligns with the overall mite prevalence observed in the Portuguese territory.
The main environmental exposure factors were plants and trees, soft toys, rugs and curtains, and domestic pets.Furthermore, most individuals lived in rural areas; however, it is not possible to establish a relationship with asthma in this group because the geographical area corresponding to this sample was mostly rural.
We believe that the high prevalence of sensitization, seen in all allergological pathologies and all age groups, may reflect the influence of these housing and environmental conditions in the northern coastal area of Portugal, which leads to early and daily exposure to these allergens.
The main exacerbating factors recorded were exercise, season, and laughter, all of which have been shown in the literature to cause bronchoconstriction [1].However, we would like to highlight the lack of data, as there was often no reference to it in the patient record.
Similar to another study from Portugal, the authors corroborated various associations between atopic diseases and contextual factors.For instance, individuals with both asthma and AR were associated with exposure to certain plants and dust mites [10].In our study, we also found associations between AD and AR in second-degree relatives, urban environments, and the presence of specific plants.

Limitations and future directions
The fact that this study was conducted on a limited size and convenience sample, encompassing patients who consecutively attended the pediatric unit of Unidade Local de Saúde do Alto Minho, are two important limitations of this study.Additionally, the data gathered from pediatric appointment records lacked standardization, leading to a lack of information on some variables.Furthermore, the exclusive focus on individuals with asthma prevents comparisons to the non-asthmatic subset.It would be interesting to conduct further research investigating the contrast between this study's findings with those of individuals who do not suffer from asthma while highlighting the disparities in risk factors or family history.
Despite some limitations, this study improves the characterization of the pediatric asthmatic population in the Alto Minho region, resulting in an important opportunity to increase the understanding of the disease in younger patients who exhibit risk factors.This newfound insight will hopefully lead to prompt diagnoses and effective treatments.
The characterization of the pediatric population of this area allows pediatricians and family doctors, who serve as primary hubs for those seeking allergic pathology advice, to stay alert regarding allergy signs and provide better care.Testing asthma patients for allergens allows them to be identified and for environmental avoidance measures and targeted therapeutic strategies to be implemented.

Conclusions
In summary, our study on pediatric asthma in Alto Minho, Portugal, reveals significant associations between asthma and atopic conditions, highlighting local sensitization patterns and environmental influences.While acknowledging limitations, including sample size constraints, this study provides crucial insights for prompt diagnosis and targeted treatment.The findings underscore the importance of considering family history and regional factors in managing pediatric asthma.However, further investigation is required regarding the associations between atopic disease and contextual factors.Authors acknowledge that larger and more diverse studies are warranted to validate and expand upon these findings, but this research lays a foundation for improved care in the pediatric population of Alto Minho.

FIGURE 1 :
FIGURE 1: Flowchart showing the selection process.

FIGURE 2 :
FIGURE 2: Schematic representation of the participants' age distribution.The data are represented as N. Sample: n = 239.Dark blue = male individuals; light blue = female individuals

FIGURE 3 :
FIGURE 3: Schematic representation of the total sample according to different body mass index levels.The data are represented as N. Sample: n = 157.

FIGURE 4 :
FIGURE 4: Schematic representation of the total sample according to atopic diseases (allergic rhinitis, atopic dermatitis, and food allergies).The data are represented as N. Sample: n = 221.

FIGURE 5 :
FIGURE 5: Schematic representation of environmental exposures, exacerbation factors, and skin prick test results.The data are represented as percentage (%).For the majority of variables: dark blue = yes; light blue = no.Considering urban vs. rural environment: dark blue = urban; light blue = rural

TABLE 1 : Distribution of the total sample, stratified by age according to the different body mass index (BMI) levels.
The data are represented as N and percentage (%).Sample: n = 157.