1. Introduction
Allergic rhinitis (AR) is an immunoglobulin E-mediated inflammatory disorder that affects the nasal mucosa and is clinically characterized by symptoms, such as nasal congestion, itching, sneezing, and rhinorrhea [1, 2]. These symptoms significantly impair the patients’ quality of life. The pathogenesis of AR is a complex process influenced by both genetic and environmental factors that affect the immune system and host responses [3, 4].
Meteorological and environmental variables, including temperature, humidity, and particulate matter concentration in the air, are closely associated with the subjective symptoms of AR [5]. Recent ecological transformations driven by accelerated urbanization have further increased the global disease burden of AR [4].
Globally, AR prevalence continues to escalate, currently affecting 10% to 30% of adults and 40% of the pediatric population. Approximately 250 million people in China have AR [6, 7], costing 326.8 billion yuan annually for treatment [8]. Two surveys conducted by our team in 2005 and 2011 reveal an increase in the prevalence of self-reported AR from 11.1% to 17.6% over a 6-year period [9].
Risk factors for AR include indoor allergens, smoke, pollen, food, mites, odors, and smoke [9, 10].
Given China’s large population and vast geographical expanse, there are substantial variations in geographical characteristics, climatic conditions, economic status, and living habits across regions. These factors contribute to significant regional disparities in the AR prevalence in the country. Recent cross-sectional studies involving multiple natural populations have demonstrated that the prevalence of AR varies considerably, ranging from 8.7% in Beijing to 32.4% in the steppe regions of northern China [11].
Furthermore, studies have highlighted that the AR prevalence exhibits distinct regional characteristics. In the Inner Mongolia Autonomous Region, the prevalence rates were 7.96% in Baotou City, 18.6% in Tongliao City, and 52.9% in Xilin Hot City, suggesting a partial correlation between topography, vegetation distribution, and pollen species [6, 9].
Northwest China’s Shaanxi Province, characterized by its continental climate and seasonal peaks in Artemisia annua pollen concentration, is recognized as an endemic region for AR. Xi’an, the provincial capital, is situated centrally within the Guanzhong Plain, bordered by the Weihe River to the north and the Qinling Mountains to the south, and features notable elevation variations and diverse ecological environments. In Xi’an, the prevalence of AR was 9.1% in 2005 and increased to 16.5% in 2011 [10, 12], a trend strongly correlated with exposure to predominant airborne allergens, such as mugwort pollen.
Despite the high levels of pollen exposure and historical prevalence rates in Xi’an, no comprehensive epidemiological studies have been conducted since 2011. In recent years, efforts to establish an “allergy-friendly urban landscape” in Xi’an have led to changes in vegetation distribution. Consequently, it is imperative to understand these environmental impacts to develop targeted prevention strategies and interventions aimed at mitigating the burden of AR on individuals and the health care system.
With the strong support of the National Health Commission, we conducted a telephone questionnaire survey in 2022 to assess the prevalence of AR in the resident population of Xi’an and identify the major allergens, influencing factors, major causes of sensitization, visits, and medications to inform public health strategies to improve patient outcomes by addressing these objectives.
2. Methods
2.1. Research area and participant selection
This study was conducted in Xi’an City in the middle of the Guanzhong Plain in Shaanxi Province. The city is located between 33°42′–34°45′ north latitude and 107°40′–109°49′ east longitude, high in the northwest and low in the southeast, and the altitude of the city ranges from 400 to 3867 m, with a total area of 5145.86 km2.
The calculation of the sample size was based on a permanent resident population of 13.163 million in Xi’an in 2021. Using a standard prevalence-based formula [N=(Z1−α2δ)2p(1−p)deff/r] (N represents the sample size, δ represents the allowed error, Z1 represents the Z value corresponding to the confidence level, α represents the test level, p represents the prevalence rate, deff is the design effect, r is the response rate, and at a test level of 0.05.) with a 16.5% prevalence rate from a 2011 study, a 0.05 test level, and a 1% allowable error, the required sample size is 1,895. With multistage sampling, this increases to 2,843.
Considering an 85% response rate, at least 3,350 cases were needed. It represented approximately 0.25‰ of the total resident population in Xi’an.
This cross-sectional study was conducted from June to October 2022, according to the population distribution across the different regions of Xi’an. The study investigated adult residents (aged 18 years or older) residing in Xi’an who could independently complete the telephone questionnaire. Telephone communication, including mobile phones, was used to establish the local number prefix, whereas the last 4 digits were randomly selected in a uniform format.
We contacted the telephone until other parties were connected and interviewed. A call was made up to 3 times if the line was busy or unresponsive. Respondents who have resided in urban areas for more than 12 months are eligible to complete the general questionnaire.
Patients diagnosed with rhinitis will be directed to the rhinitis-specific questionnaire, whereas those without rhinitis will complete the rhinitis incidence questionnaire. This study was approved by the Ethics Committee of Beijing Tongren Hospital (Ethics number: TRECKY2021-194, Chairperson Prof Yan Liu).
2.2. Interviewer questionnaire
The questionnaire was developed by the Department of Allergy at Beijing Tongren Hospital. Asthma and Allergies in Childhood [13] and the European Community Respiratory Health Survey questionnaires [14] were used in the study. There were 2 parts to the questionnaire: basic demographic data and factors related to allergic diseases.
The basic demographic data included age, sex, and ethnicity. Allergy-related factors included smoking, home decoration, and pet ownership. The second section addresses the challenges in diagnosing allergic diseases, such as AR, allergic conjunctivitis, asthma, atopic dermatitis, and food allergies.
Patients who reported AR and/or AC during the phone screening received a detailed questionnaire. The questionnaire covered the history of allergic disease, symptom onset and timing, family history, medication use, and disease control. Following the 2022 revised “Guidelines for the Diagnosis and Treatment of AR in China” [15], patients were categorized into mild or moderate-to-severe AR based on condition severity.
Patients with mild AR had minor symptoms that did not notably affect their quality of life, including sleep and daily activities. However, those with moderate-to-severe AR experienced significant symptoms that greatly affected their quality of life.
2.3. Statistical analysis
Statistical analyses were performed using SPSS software version 27.0. For continuous variables, assuming a normal distribution, the results are presented as the mean ± standard deviation, whereas categorical data are expressed as frequencies and percentages. The rank sum test was used to analyze data related to disease severity grades.
Differences between groups were assessed using independent sample t tests for normally distributed continuous variables and chi-square tests for categorical variables, with statistical significance determined at a threshold of P < 0.05.
3. Results
3.1. Participants and demographic characteristics
A total of 83,492 mobile phones were contacted for this survey, resulting in 11,885 respondents agreeing to participate, which corresponds to a successful call rate of 14.23%. Among those who answered, 271 were disqualified during the screening process, 5,440 declined to continue the interview midway, 118 experienced communication barriers, and 2,706 disconnected immediately after answering. Finally, 3,350 participants completed the survey.
Considering the permanent population of Xi’an in 2021 (13.163 million), the survey participants represented approximately 0.25 per thousand of the total permanent population. The respondents were distributed across 17 districts and counties in Xi’an, including 496 from Weiyang District, 192 from Xincheng District, 224 from Beilin District, 336 from Lianhu District, 246 from Banqiao District, 555 from Yanta District, 170 from Yaoling District, 160 from Lintong District, 12 from the International Port Area, 382 from Chang’an District, 175 from Gaoling District, 155 from Hu County, 23 from the Chanba Ecological Area, 27 from Qujiang New District, 53 from Xixian New Area, 132 from the High-Tech Industrial Development Zone, and 12 from the Economic and Technological Development Zone.
There were 3,350 adult respondents, covering 11 districts in the Xi’an region. The demographic data were presented in Table 1. Of the total number of respondents, 334 self-reported their AR symptoms.
The mean age of the adult AR patients was 42.5 ± 13.9 years, with male patients averaging 43.30 ± 14.11 years and females averaging 41.40 ± 13.59 years. Male AR patients constituted 9.6% of the male respondents, while female AR patients constituted 10.5% of the female respondents. Statistical analysis revealed no significant difference in the prevalence of AR between sexes or among different ethnic groups within the Xi’an region.
Among the participants, 20.1% of the self-reported AR patients and 5.1% of the total respondents had a family history of allergic diseases. The prevalence of AR among individuals with a family history of allergic diseases was 30.3% compared with 8.5% among those without such a history. Thus, these data indicate a higher prevalence of AR in individuals with familial predisposition to allergic diseases.
3.2. The prevalence of AR in 11 districts of Xi’an
In Xi’an, 334 out of 3,350 telephone follow-ups reported AR symptoms, indicating a 10.0% overall prevalence. The district prevalence rates were as follows: Central District, 14.1%; Gaoling, 13.2%; Yanta, 11.3%; Lianhu, 10.9%; Baqiao, 9.8%; Economic and Technological Development Zone, 8.3%; Qujiang New Area, 7.4%; Yanliang, 7.1%; Chanba Ecological District, 4.3%; Lintong, 3.8%; and International Port District, 0.0%. The participants were categorized based on their residence in the urban and suburban groups, with an AR prevalence of 11.0% in urban areas and 8.3% in suburban areas, indicating a higher prevalence of AR in urban areas (P = 0.002).
3.3. Analysis of AR clinical characteristics in Xi’an
In this survey, the mean duration of AR among patients was 6.45 ± 3.40 years, with males averaging 6.37 ± 3.44 years and females averaging 6.57 ± 3.34 years. Mild AR was observed in 65% of the patients, while 35% had moderate to severe AR. Additionally, 22.8% had perennial AR and 77.2% had seasonal allergic rhinitis (SAR).
An investigation into the factors worsening AR symptoms found that 35.3% experienced severe symptoms during the pollen season, 31.1% due to dust, 11.4% from pet contact, 43.7% due to poor air quality, and 35.0% from other triggers such as passive smoking and indoor decoration. The analysis showed that 45.6% of urban AR patients blamed poor air quality and haze, whereas 41.7% of suburban patients pointed to pollen as the main cause (Table 2). Additionally, Table 3 indicates that 31.3% of women and 18.9% of men had other allergic diseases, suggesting that women with AR were more prone to comorbid allergies (P = 0.009).
3.4. AR diagnosis and treatment in Xi’an
As illustrated in Table 4, of the 334 AR patients surveyed, 38.0% underwent allergen tests, 55.4% received medication, and 67.4% reported symptoms in the past 2 years. Comparative analysis revealed no statistically significant differences in AR diagnosis rates or medication preferences between urban and suburban populations (all P > 0.05). The proportions of disease control levels in the past 2 years were similarly distributed, with “basic control” representing the highest proportion (44.7% vs 50.0%, χ² = 2.854, P = 0.583).
4. Discussion
This study is the first to stratify according to the demographic characteristics, residential areas, and AR disease characteristics of 17 districts and counties in Xi’an, which is the current survey of the prevalence of allergic diseases in people aged 18 years and older, with a large sample size and wide coverage. This survey complemented the AR epidemiological data of permanent residents of Xi’an over the past 10 years. This study found that the prevalence of self-reported AR in Xi’an was 10.0%, the AR patients in this region mainly had mild AR, and the rate of AR patients with other allergic diseases fluctuated between 41% and 51.1%.
The prevalence of AR is a significant global health concern, affecting a substantial portion of the global population. The prevalence of AR varies widely across different regions and is influenced by various environmental, genetic, and lifestyle factors. The AR varies significantly by region in adults.
An Italian study of 3,383 adults with rhinitis found that 82.4% had AR, with 56.1% experiencing a moderate-to-severe persistent form [16]. In contrast, a study examining the burden of AR across America, Latin America, and the Asia-Pacific region found that the prevalence of physician-diagnosed AR was 14% in American adults, 7% in Latin American adults, and 9% in Asia-Pacific adults. This variation highlights the regional differences in the prevalence and management of AR, with nasal congestion being the most common and bothersome symptom reported in adults [17].
Further research into the prevalence and diversity of AR in regions beyond Europe and North America has revealed even more significant variations. The prevalence of AR and allergic rhinoconjunctivitis has predominantly been investigated in children in Africa, the Asia-Pacific region, Australia, Eastern Europe, Latin America, the Middle East, and Turkey. The studies indicate wide inter- and intra-regional variations, with prevalence rates ranging from 2.9% in Turkey to 54.1% in Nigeria.
These variations are likely due to differences in exposure to sensitizing agents and risk factors, which have increased with improved living standards in some regions [18]. In China, the AR prevalence ranges from 10% to 24% and is rising annually [7]. A national survey reported the highest prevalence in Shanghai (23.9%) and the lowest in Chengdu (9.6%).
The rate was 32.4% in the northern grassland region [6, 9]. In Shenmu City, China, the AR prevalence was 41.5% in plains and 22.1% in hilly areas, indicating that notable geographical differences and environmental factors are key risk factors [19].
The study found a 10.0% prevalence of AR among adults in Xi’an, which is moderately high in Northwest China but lower than that in eastern cities such as Beijing (17.6%) and Guangzhou (19.2%). This could have been influenced by Xi’an’s industrial and climatic conditions. Previous surveys in Xi’an showed a prevalence of 9.1% in 2005 and 16.5% in 2011.
The current lower rate may result from municipal efforts, such as pollen monitoring, increased awareness, and allergy-friendly landscaping.
This study found no significant difference in prevalence between male (9.6%) and female (10.5%) adults, consistent with previous studies [20–23], but differed from other studies, where females had a higher prevalence [24]. Epidemiological data suggest that, while AR and asthma are more common in boys during childhood, a shift occurs during adolescence and adulthood, with females exhibiting a higher prevalence of these conditions. This sex shift in prevalence is particularly evident in cases of AR and concurrent asthma [25].
The underlying reasons for this sex disparity in AR prevalence are multifaceted and may involve hormonal influences. In females, cyclic hormonal changes, particularly those related to estrogen, can affect the severity and manifestation of AR. Pregnancy is another factor that can exacerbate rhinitis symptoms, leading to a specific condition known as pregnancy rhinitis [26].
Furthermore, the interaction between inflammatory cells and neurogenic responses in AR may differ between sexes. Studies have demonstrated that female patients with AR tend to have higher levels of neurokinin substance P, a neuropeptide associated with inflammation, both before and after an allergen challenge. This suggests a gender-related difference in the regulation of neurogenic inflammation, which could contribute to the distinct symptom profiles observed in females with AR [27].
However, female patients with AR had a higher rate of comorbid allergic diseases, suggesting that estrogen may increase multisystemic allergy risk by affecting the Th2 immune pathway [28, 29], similar to Kirsebom et al.’s mouse model [30]. Additionally, experimental studies indicate that female patients with AR demonstrate higher levels of sensitivity to irritants and airway hyperresponsiveness than male patients [27].
The risk of developing AR (30.3% vs 8.5%) was significantly influenced by genetic factors, as evidenced by a strong association with a family history of allergy in our study. This genetic predisposition is supported by various studies that have identified specific genetic loci and polymorphisms that are associated with AR. For instance, genome-wide association studies (GWAS) have identified multiple risk loci for AR, implicating genes involved in immune pathways and antigen binding [31].
Additionally, polymorphisms in genes such as Interleukin‑4 receptor (IL-4R), Fc fragment of IgE receptor Ia (FCER1A), IL-12B, and IL-27 have been associated with increased susceptibility to AR, suggesting that these genetic variations may serve as potential biomarkers for the disease [29, 32, 33]. Moreover, the interaction between genetic and environmental factors plays a crucial role in AR development. The hygiene hypothesis, which posits that reduced microbial exposure in early life can lead to an imbalance in immune responses, further underscores the importance of genetic predisposition in conjunction with environmental influences [34].
Studies have also shown that specific genetic variants in IL-33 are associated with AR, highlighting shared genetic risk factors with other allergic conditions such as asthma [35].
The prevalence of AR is notably higher in urban areas (11.0%) than in suburban or rural settings (8.3%). This phenomenon can be attributed to various environmental and lifestyle factors prevalent in urban environments. Studies have shown that urban areas, with higher levels of air pollution and diverse allergen exposure, contribute significantly to the increased prevalence of AR [36].
The population of patients with AR is predominantly affected by pollen, with approximately half experiencing other allergies. Patients residing in grassland regions exhibit more severe symptoms, likely due to increased pollen exposure resulting from the high density of vegetation, a factor that can exacerbate symptoms in individuals in northern China [37]. Air pollution (43.7%) and pollen (35.3%) were identified as the primary predisposing factors directly linked to the industrial structure of Xi’an and the allergen characteristics of the Guanzhong Plain.
In Xi’an, 38.0% of patients underwent allergen testing, the medication usage rate was 55.4%, and 66.4% managed to control symptoms with medication. These figures surpass those reported in research conducted on the Chinese population in Singapore [38], indicating an increased awareness of allergic diseases in Xi’an in recent years. Notably, there was no significant difference between the urban and rural areas, suggesting a balanced development of medical resources.
An analysis of the proportions of AR medication use and diagnosis revealed that among those attempting to manage their AR through diagnosis or medication, a greater number engaged in self-medication without formal AR diagnosis. This under-management pattern is not unique to our study. The burdens associated with AR have been documented in various study populations despite the relatively high prevalence estimates of the condition [39, 40].
A European survey revealed that only 19% of individuals are aware of AR, despite 70% receiving a diagnosis from a medical professional [41]. Furthermore, as AR is not life-threatening, many individuals tolerate their symptoms without seeking medical intervention [42]. Adherence to the use of nasal hormones may be a key impediment to optimizing the management of nasal hormones.
However, the diagnosis and treatment of AR in Xi’an are inadequate, with limited and inconsistent treatment methods. To address this, Xi’an should focus on personalized treatment, pay more attention to those with a family history of allergies and long-term urban residence, and enhance awareness of AR to encourage early symptom recognition and standardized treatment. Second, it is crucial to monitor airborne pollen, particularly in spring and fall, by setting up atmospheric pollen monitoring points and collaborating with meteorological departments.
This will aid in providing pollen broadcasting services and guidance for AR patient travel, protection, and medication. Attention should also be paid to controlling seasonal AR episodes to reduce their impact on quality of life and prevent complications such as allergic asthma. Third, early diagnosis and treatment are vital because China has a high number of patients with AR.
To reduce AR prevalence, lower societal costs, ease patient suffering, and lessen economic burden, it is crucial to enhance early diagnosis and screening for everyone, identify allergens, and implement standardized preventive and treatment measures. This will help control AR effectively and support the Healthy China Initiative. Additionally, conducting epidemiological studies on AR will inform public health policies and strategies and improve the prevention and control system to protect public health.
4.1. Limitations and perspectives
This study has several limitations. First, it relies on self-reported AR data from telephone surveys without allergen testing, potentially including cases of chronic rhinitis. Second, the response rate aligns with previous studies, but may differ demographically between respondents and nonrespondents, necessitating improved interviewer training.
Third, the cross-sectional design did not allow for the establishment of a causal relationship.
5. Conclusion
An epidemiological survey in Xi’an revealed a 10.0% prevalence of AR among adults, with higher rates in urban areas and those with a family history of allergies. SAR is more common, with dust being the primary allergen. Among the patients, 38.0% underwent allergen testing, 55.4% used medication, and 66.4% had controlled symptoms in the past 2 years.
It is advised to enhance AR awareness, especially in urban areas, to promote early detection and treatment and to reduce the risk of lower airway diseases.
Conflicts of interest
The authors have no financial conflicts of interest.
Author contributions
Xu Zhang wrote the manuscript. YunBo Gao, Jingyun Li, and Lin Xi collected data. YunBo Gao, Yuan Zhang, and Xu Zhang analyzed the data.
YunBo Gao, Xu Zhang, Yuan Zhang, and Luo Zhang designed the study and revised the manuscript accordingly.