Clinico-Epidemiological Profile of Respiratory Allergy Patients Attending an Allergy Centre at a Tertiary Care Hospital in Bengaluru

Introduction

Allergy is a hypersensitivity disorder occurring due to a complex interaction between genetic and environmental factors when the immune system reacts abnormally to otherwise normally inoffensive substances in the environment.¹ Allergic disorders are among the most common chronic disorders worldwide.² Allergic disorders include bronchial asthma, allergic rhinitis, allergic conjunctivitis, urticaria, angioedema, anaphylaxis, drug allergy, food allergy, and insect allergy.³

Respiratory allergies mainly include allergic rhinitis and bronchial asthma. It is the most common type of allergic disorder in both developing and developed countries, with an increasing trend all over the world.⁴ Nearly 500 million and 300 million people suffer from allergic rhinitis and bronchial asthma worldwide, respectively.⁵ The prevalence of respiratory allergy has been rising significantly in the Indian subcontinent as well.⁶ About 20-30% of the Indian population suffers from at least one allergic disease.¹

Allergic rhinitis is characterized by sneezing, running nose, nasal block, and nasal pruritis/itching and may be associated with watery eyes, redness, and pruritis of the eyes. Bronchial asthma is characterized by the presence of wheeze, shortness of breath, chest tightness, and cough that fluctuate over time and in intensity with variable expiratory airflow limitation.

Aeroallergens like pollen, dust mites, dust, animal hair, feathers, etc., are the most common offending allergens in respiratory allergy.⁷ There is a strong genetic predisposition for the development of respiratory allergy. Having parents who are atopic also increases the risk by 3-6 times. Studies have shown that in 40% of cases, rhinitis frequently precedes the development of asthma.⁸

According to WHO, the skin prick test is the gold standard test for diagnosis of allergy when performed with standardized extracts with common native environmental allergens. It is simple, quick, reliable, economical, minimally invasive, and has good sensitivity and specificity.^9-11 The pattern of allergen sensitivity in respiratory allergy patients differs with respect to geographic location and time period. Therefore, it is necessary to identify the allergen sensitivity pattern in respiratory allergy patients from time to time.

Materials and Methods

This was a descriptive study conducted at the allergy center of a tertiary care hospital in Bangalore from January 2021 to December 2021. All the respiratory allergy patients who visited during the study period were subjected to an allergy skin prick test, following the application of inclusion and exclusion criteria. Patients aged between 10 and 70 years, with a history of allergic rhinitis and bronchial asthma for six months or more, and who provided written informed consent and assent, were included in the study. Pregnant women, lactating women, patients with acute allergies, and patients who had symptoms suggestive of COVID-19 infection were excluded from the study. Sample size calculation was done assuming a 95% confidence interval and precision of 5%, using data from a study by Kumar et al., resulting in a required sample size of 173. Clearance for the study was obtained from the Institutional ethical committee.

The patient information was collected using a semistructured, pre-tested questionnaire. The details regarding the sociodemographic information, including age, sex, address, education, occupation, and income, were obtained and recorded. Socioeconomic state of the individual was assessed based on the modified Kuppuswamy classification. A skin prick test was done after obtaining written informed consent and assent from children aged 10 to 18 years, and consent was taken from the parents/guardians.

A skin prick test (SPT) was performed using 48 allergen extracts to identify allergen sensitization. The allergen extracts were procured from Creative Diagnostics Medicare Pvt. Ltd., Navi Mumbai, which included 20 pollens, 7 fungi, 5 dusts, 2 dust mites (Dermatophagoides farinae and D. pteronyssinus), 10 insects, and 4 epithelia/animal dander. SPT was performed on the flexor aspect of the arm and forearm in adults and on the back in children after cleaning with isopropyl alcohol. A drop of the allergen solution was placed on the skin, and using the sterile lancet, a prick was done to allow the allergens to enter the epidermis. The same procedure was repeated for all the allergens. A skin prick test was done with positive and negative control. The allergen was left in place for 20 minutes, and then a reading of the wheal area diameter was taken using a measuring scale. Interpretation of results was done according to Indian College of Allergy, Asthma, and Immunology guidelines. Wheal size of more than 3 mm was considered positive.¹²

Statistical analysis

Data were entered into MS Excel and analyzed using SPSS Version 23. Results were expressed as mean±SD, median with interquartile range, and as frequencies and percentages. Association between variables was tested using appropriate statistical tests like Chi square. The unadjusted odds ratio was calculated for factors of interest.

Results

The study was conducted among 173 patients with respiratory symptoms, aged between 10 and 70 years. Out of the 173, 86 (49.7%) were males and 87 (50.3%) were females. The mean age of the study subjects was 30.8±13.2 (mean ± SD), median 30, and an interquartile range of 21-38. The age and sex distribution of the study subjects is given in Table 1.

Among the 173 study subjects, 133 (76.9%) were employed and 40 (23.1%) were unemployed, which includes students and homemakers. The majority of the study subjects were graduates (62, 35.8%), followed by diploma holders (27, 15.6%). Of the 173 study subjects, 63 (35.2%) belonged to the upper middle socioeconomic class, followed by 46 (28.3%) who belonged to the lower middle class.

The most common exaggerating factors for symptoms of respiratory allergy in the study subjects were, exposure to dust (76.3%), exposure to gardens or parks (64.2%), and change in weather (43.9%), followed by bedmaking (41%) and sweeping (35.8%). Most of them experienced symptoms indoors (50.3%) compared to outdoors (32.5%). It was observed that the symptoms of respiratory allergy gradually increased from June to January, peaking in December.

Among 173 study subjects, 108 (62.4%) presented symptoms of allergic rhinitis only, 14 (8.1%) symptoms of bronchial asthma only, and 51 (29.5%) had both symptoms of both allergic rhinitis and bronchial asthma.

Among the 159 study subjects with allergic rhinitis, 59.7% reported a family history of allergic disorders. A family history of atopy was noted in 83.1% of the subjects who suffered from symptoms of bronchial asthma. The subjects also had associated symptoms of allergic conjunctivitis (54.9%), symptoms of urticaria (42%), sinusitis (35%), and recurrent respiratory tract infections (9.8%).

The most common pollens were Parthenium hysterophorus (24.3%), Amaranthus spinosus (23.7%), Prosopis juliflora (23.1%), Azadirachta indica (21.4%), Ricinus communis (20.2%), and Chemopodium album (20.2%). The most common fungi were Alternaria alternata (18.5%), Aspergillus flavus and A. fumigatus (15%), followed by Cladosporium herbarum (13.9%). Most common dust was paper dust (30.1%), house dust (28.3%), cotton dust (23.1%), and wheat dust (22.5%). Dust mite sensitivity was present for Dermatophagoides pteronyssinus (DP) (50.9%) and D. (DF) (45.1%). Study subjects were also sensitive to dog epithelia (25.4%), pigeon droppings (17.3%), cat dander (16.2%), and pigeon feathers (14.5%). The most common among insects were cockroaches (26%), followed by honey bees and mosquitoes (24.3%) (Table 2).

A comparison was made between study subjects with positive skin prick tests and those with negative skin prick tests (Table 3). 

Discussion

In the present study, 50.3% of subjects were female and 49.7% were male. This is comparable to the study by Giriyanna Gowda et al.,which showed a female preponderance of 59.7%, and to the study by Roohi Rasool et al. which reported a male-to-female ratio of 1:1.5.^{13, 17} An age of onset below 20 years was observed in 23% of the subjects, which is similar to findings from studies conducted in Delhi by Raj Kumar et al. and Kammili et al., where approximately 20% of patients were under 20 years of age.^{14, 15} The majority of study subjects in the present study belonged to the 21-40 year age group, indicating that respiratory allergies primarily affect individuals in their productive years, potentially reducing both quality of life and earning capacity. Family history of atopy was noted in 60% of patients with allergic rhinitis and 80% of patients with bronchial asthma in the present study. This is higher than the reported 50% by Giridhar BH et al., and 43.2% by Giriyanna Gowda et al., Genetic predisposition plays a significant role in developing allergic disorders.^{4, 13}

In the present study, house dust mite (HDM) was the most commonly sensitizing aeroallergen, with 50.9% of subjects sensitized to Dermatophagoides pteronyssinus (DP) and 45.1% to D. farinae (DF). Similarly, a study conducted in Chennai by Nagaraju Kuravi et al., reported that 63% of participants showed equal sensitivity to both DP and DF.¹⁶ In a study conducted in Kashmir by Roohi Rasool et al., 46% of allergic rhinitis patients and 32% of patients with bronchial asthma showed sensitivity to dust mites.¹⁷ Another study conducted in Nagpur showed 49% sensitivity to dust mites. Kammili et al., in their study conducted in Bangalore in 2019 reported dust mites as the most common allergens, with 32.48% of patients showing sensitivity.¹⁵ In a 2011 study conducted in Bangalore by Giriyanna Gowda et al., DP sensitization was observed in 52.5% of subjects and while DF sensitization was seen in 46%.¹³ In a study by Khan A et al., in Lucknow, dust mite sensitivity was noted in 20.7% of the subjects, while Rajkumar et al., reported skin sensitization to dust mites in 13% of cases, which is similar to many studies conducted in the northern part of the country.^{14, 18} A study by Supa Oncham et al., (2018) in Thailand reported skin sensitivity to DP in 50.1% of subjects and to DF in 32%.¹⁹ Sensitization to house dust mites is also high in other parts of the world, including Germany (34.1%), Bosnia (27.5%), Iran (86%), and Pakistan (82%).^19-22 These studies indicate that dust mites are potential triggers for respiratory allergies. The increasing sensitization to house dust mite allergens in recent years may be attributed to factors such as, climatic conditions, urbanization, and a predominantly indoor lifestyle.

The present study shows positivity to paper dust in 30.1%, followed by house dust in 28.3%. In a study conducted in Lucknow by Giridhar BH et al., both wheat and house dust showed a prevalence of 30%.⁴ In 1986, Duc J et al., reported a 50% frequency of hypersensitivity to dust among patients with rhinitis and bronchial asthma.²³ Acharya PJ in the year 1980 reported the prevalence of skin reactivity as 24.5% among patients with nasobronchial allergy.²⁴ A study by Roohi Rasool et al., found that various types of dust, such as cotton dust, grain dust, sawdust, and paper dust, affected a significant proportion of the study subjects.¹⁷

The most common pollens causing positive reactions on the skin prick test in the present study were Parthenium hysterophorus (24.3%), Amaranthus spinosus (23.7%), Azadirachta indica (21.4%), Ricinus communis (20.2%), and Chenopodium album (20.2%). A study by Nagaraju Kuravi et al., showed that the majority were sensitive to Prosopis juliflora (27.8%), which is also a common tree pollen causing skin sensitivity in the present study (23.1%). The common weed pollens identified in the study by Nagaraju Kuravi et al., like Parthenium (23.3%), Chenopodium album (22.8%), and Amaranthus spinosus (22.1%), are consistent with the findings of the present study.¹⁶ A study conducted in Central Nagpur by Arbat A et al., found that 21.8% reacted positively to pollens.²⁵ A study conducted in Delhi by Raj Kumar et al., reported weed pollen to be one of the most important offending allergens (21.8%), which is comparable to the results of the present study.¹⁴ A study by Giriyanna Gowda et al., also showed similar results, i.e., 20.8% sensitivity to weed pollens.¹³ A study conducted in Udaipur in the year 2018 reported pollen sensitivity in 43.8% subjects.²⁶ A study conducted by Roohi Rasool et al. in Kashmir found that pollens affected 52% of the study subjects, which may be attributed to the proximity of inhabitants to meadows, farms, and forests in the region.¹⁷ In studies by Lokaj Berisha V et al., and Payam Payandeh et al., in Iran, pollen sensitivity on SPT was observed in 63.4% and 82% of subjects, respectively.^21-22 Nicola Wagner et al., in a study conducted in Germany, reported grass pollen sensitivity in 74.9% and birch pollen sensitivity in 71.1% of subjects.27 Payam Payandeh et al., specified pollen allergy to Salsola kali (82.3%), pigweed (65%), and tree mix (51.7%).²⁸ It has been observed that pollen sensitization varies widely across the geographical locations. The variation may be attributed to changes in the pattern of vegetation, which fluctuate over time due to the changing geo-climatic conditions.

In the present study, dog epithelia was the most common offending allergen noted in 25.4%, followed by pigeon droppings (17.3%), cat dander (16.2%), and pigeon feathers (14.5%). In a study conducted in Chennai, the most common animal dander was dog epithelia, followed by cat epithelia.¹⁶ A study conducted in Kashmir in 2013 showed that study subjects were positive to sheep wool, probably due to occupational exposure in people involved in sheep husbandry.¹⁷ In several studies conducted in Lucknow from 2001 to 2021, such as the study conducted by Giridhar BH et al., buffalo dander showed 37.5% positive results, while cow dander showed 25%.⁴ Khan A et al., observed buffalo dander to be the most common animal dander resulting in skin reactivity.¹⁸ Gupta et al., reported buffalo dander as the most common allergen yielding positive reactions, likely because most patients in the study belonged to rural areas.²⁹ Prasad et al., reported cow dander (18%) and horse dander (14%) to be the most common allergens among danders.²⁴ Animal dander sensitization varies depending on the occupation, religious practices, and place of living. Higher sensitivity to dog dander in the present study could be due to the presence of dogs as pets and the urban setting of the study area.

The present study results were compared with a similar study conducted at our institution a decade ago.¹³ Increased sensitization was observed in the present study for paper dust, cockroach, dog epithelia, and the fungus Alternaria alternata.

Conclusions

A significant number of study subjects had a family history of atopy, highlighting it as a major risk factor for allergic disorders. The most commonly identified such allergens through skin prick testing included dust mites as and Dermatophagoides pteronyssinus Dermatophagoides farinae, various pollens like Parthenium hysterophorus, Prosopis juliflora, and Amaranthus spinosus, as well as dog epithelia and fungi like Alternaria alternata. Evaluating the epidemiological factors contributing to allergic diseases and identifying allergen sensitization at an early stage can aid in recommending avoidance strategies, initiating appropriate pharmacotherapy, and considering allergen immunotherapy. This comprehensive approach not only targets long-term relief but also helps prevent disease progression and promotes better overall health outcomes.

Conflict of Interest

Nil

Acknowledgments

We would like to thank the Dean and Principal, Medical Superintendent, and all the faculty of the Department of Community Medicine, Kempegowda Institute of Medical Sciences and Hospital for moral support and encouragement in conducting the study. We would also like to thank all the patients who participated in the study.