Trends of sensitization pattern to aeroallergens among the patients with allergic rhinitis and/or bronchial asthma in Bangalore: A cross sectional study

Abstract

Background

Allergic rhinitis (AR) is rather erroneously viewed as a trivial disease. It is a chronic or recurrent allergen-specific, IgE-mediated inflammation that primarily affects the membrane lining the nose. However, due to the united airway concept, it is also found to be associated with bronchial asthma. AR commonly remains underdiagnosed or misdiagnosed and thus, leads to either undertreatment or inappropriately prolonged medication.

Methods

Four hundred adults having allergic rhinitis and/or bronchial asthma, fulfilling the criteria as per Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, underwent skin prick test (SPT). Those having rhinitis due to nonallergic causes were excluded. SPT was carried out using a customized panel of 21 aeroallergens. The result was compared with the reaction of histamine, which was taken as a positive control.

Results

Majority of 228 (58.02%) of the patients showed a positive reaction to the tested panel of allergens. However, 165 (41.98%) showed no reaction to the tested panel of allergens can be due to various factors like reduced skin sensitivity, antihistaminic medications, etc.

Conclusion

Skin prick test accurate test for determining offending allergens in allergic conditions. House dust mites (41%) were the most common offending aeroallergen among patients with allergic rhinitis and/or bronchial asthma residing in Bangalore. The identification of offending aeroallergens have helped patients in avoiding unnecessary medications, take appropriate preventive measures or plan appropriate immunotherapy.

Introduction

Allergic rhinitis (AR) is an IgE-mediated inflammation affecting the mucous lining of the nose and is characterized by rhinorrhea, nasal congestion, recurrent sneezing episodes, itching, and/or postnasal drip.¹ AR is associated with other allergic disorders such as bronchial asthma, sinusitis, otitis media, eustachian tube dysfunction, etc., due to the “United airway concept.” It is also reported to be associated with other conditions like urticaria and eczema. Globally, AR is the commonest form of allergic disease, and it has a significant impairment of the quality of life of the affected population.² AR remains underdiagnosed or misdiagnosed and is often undertreated in many countries resulting in overuse of medications.³

According to Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, (2016), AR is defined when two or more of the following symptoms of rhinorrhea, nasal itching, nasal blockade, or sneezing are present. The symptoms are considered relevant when they last for at least 1 h/day for 4 or more days a week and also for 4 or more weeks a year.⁴ Based on duration, symptoms are categorized as intermittent, having symptoms <4 days/week or <4 weeks/year, whereas persistent symptoms are symptoms of 4 or more days a week or >4 weeks a year. Furthermore, the grading of severity is either mild or moderate-severe based on the absence or presence of sleep disturbance and impairment in daily activities, school, and work, respectively.¹

AR affects about 10% to 30% of the adults and even a higher proportion of children. It affects nearly 500 million people across the world, with approximately 100 million of the affected population living in the Indian subcontinent. AR is known to have a high deterioration in work functioning as compared to other comorbidities like DM and hypertension. Although not a severe disease, AR and medication used for symptomatic improvement has been reported to have a great impact on the quality of life (QoL), impairments in social life, productivity at school or work, and implies elevated social costs and a burden on the socioeconomic system.⁵

The treatment of allergic rhinitis involves avoidance of the allergen, pharmacotherapy, immunotherapy, and patient education, based on the severity of symptoms. Correct identification of offending allergens has significantly aided in avoidance of allergens, planning targeted immunotherapy, and educating the patient.⁶

Skin prick test (SPT) is the gold standard, used widely in the diagnosis of IgE-mediated allergic conditions.³ It also carries the benefit of being visually appreciable to the patient, thus making patient counseling easy. The ease of administration and its reliability of the test has helped in the formulation of targeted allergen immunotherapy for effective treatment of allergic disorders.⁷

There are very limited studies in India that have observed the aeroallergens sensitization among patients with allergic rhinitis and/or bronchial asthma. The aim of this study was to determine the offending aeroallergen among the allergic rhinitis and bronchial asthma patients residing in Bangalore in order to improve the quality of life by adopting appropriate avoidance measures and plan targeted immunotherapy in pharmacotherapy resistant cases.

Materials and methods

This study was conducted at an Allergy Clinic of a tertiary care center, Bangalore, from May 2017 to Apr 2019. A total of 400 patients were included in this study.

Inclusion criteria:

• 1.Age 18–65 yrs
• 2.Case of Allergic rhinitis and/or bronchial asthma, based on the Allergic Rhinitis and its Impact on Asthma “ARIA” guidelines - 2016

• 3.Residing in Bangalore for a minimum of last 12 months duration

Exclusion criteria:

• 1.Pregnant/lactating women
• 2.Those having rhinitis due to nonallergic cause
• 3.Dermatographism over upper limb skin
• 4.On oral/intranasal antihistaminics and/or steroids in the last 7 days

A detailed history, clinical examination, and investigations, such as absolute eosinophil count and total serum IgE were evaluated. The patients were asked to discontinue oral antihistaminics, steroids, and intranasal drugs 7 days and 3 days, respectively, prior to the test. Informed consent was obtained, which was approved by the institutional ethics committee.

The test was performed with 21 aeroallergen extracts, which included nine species of pollen, seven species of fungi, and three species of house dust mite.

Skin prick testing (SPT) was performed on the flexor aspect of the arm and forearm. The allergen drops were instilled over the flexor aspect of forearm, and then superficial intradermal pricks were given to expose the allergen to superficial layers of the dermis. The reaction was measured after a duration of 20 min. The interpretation of results was carried out in accordance with the SPT (Australasian Society of Clinical Immunology and Allergy) for the diagnosis of allergic diseases.

Interpretation

During the test, histamine was used as a positive control. The test was considered valid if the histamine wheal was 03 mm or greater. Those having histamine wheal reaction lesser than 03 mm were considered invalid and were excluded from the study.

Further, a wheal of 03 mm or greater than that of histamine wheal was taken to indicate the presence of specific IgE to the allergen tested. As shown in Image 1, reactions that had a wheal diameter of 03 mm or more than that of histamine wheal were considered positive, and those with a diameter lesser than 03 mm were negative reactions. The sensitization patterns were then noted and analyzed.

Image 1.

Skin prick test.

Results

Age and gender

The study was carried out among the adult (18–65 yrs) population only. A total of 220 (55%) males and 180 (45%) females were included.

Pattern of sensitization

Aeroallergen sensitization, as shown in Fig. 1 was seen in 58.02% of patients. The remaining patients (41.98%) did not show sensitization to any of the allergens tested. This finding was consistent with Rasool et al.⁸ wherein offending aeroallergens were identified in 68.5% of allergic rhinitis patients by SPT alone.

Fig. 1.

Pie chart of the total number of allergens a person was sensitized in the study population (N = 393).

Among the sensitized population, most of the individuals were found sensitized to a single allergen (monosensitized), and lesser found sensitized to two or more allergens (polysensitized). As depicted in Fig. 2, 203 (51.65%) were positive for one allergen, 24 (6.11%) were positive for two allergens, and 1 (0.25%) was positive for three allergens.

Fig. 2.

Pie chart of summary of the total number of allergens a person was sensitized in the study population (N = 393).

In our study, HDM was the most common sensitization noted (41%). The predominant allergens (Dermatophagoides pteronyssinus – 36.9%, Dermatophagoides farinae – 22.4% and Acarus siro - 15.8%). As shown in Fig. 3, HDM sensitivity was commonest in the allergic rhinitis, asthma, and rhinitis + asthma groups. This result is consistent with several other studies from India and Asia that have established HDM sensitization as most commonly associated with allergic airway diseases.⁹

Fig. 3.

Bar chart of house dust mites sensitization in the study population (N = 393).

To a lesser extent, sensitization was noted to pollens (17.8%) and least to fungi (5.9%).

In the sensitization pattern, as shown in Fig. 4, most of the patients were sensitized with house dust mites,88 (22.4%) people sensitized to D. farinae, 145 (36.9%) sensitized to D. pteronyssinus, and 62 (15.8%) to Acarus siro. Among the pollens, 24 (6.1%) were sensitive to Mugwort, 18 (4.6%) to Lamb quarter, 12 (3.1%) to England plantain, 11 (2.8%) to Short ragweed, 11 (2.8%) to corn, 16 (4.1%) to Bermuda grain, 11 (2.8%) to Timothy grass, 4 (1.0%) to Rye glass and 15 (3.8%) to Timothy Kentucky bluegrass.

Fig. 4.

Bar chart of pollens sensitization in the study population (N = 393).

Among the fungus, as shown in Fig. 5, 3 (0.8%) were sensitive to Botrytis cinerea, 6 (1.5%) to Alternaria tenuis, 9 (2.3%) to Aspergillus fumigatus, 7 (1.8%) to Cladosporium herbarum, 5 (1.3%) to Heliminthosporium, 1 (0.3%) to Penicillium notatum and 5 (1.3%) to Rhizopus nigricans.

Fig. 5.

Bar chart of fungus sensitization in the study population (N = 393).

As collectively shown in Fig. 6, 161 (41.0%) were sensitive to house dust mites, 70 (17.8%) were sensitive to pollens, 23 (5.9%) were sensitive to fungus, 3 (0.8%) were sensitive to house dust mites + Fungus, 20 (5.1%) were sensitive to house dust mites + pollens, 1 (0.3%) was sensitive to house dust mites + pollens + fungus and 4 (1.0%) were sensitive to pollens + fungus.

Fig. 6.

Pie chart for the total number of patients sensitized (N = 393).

As shown in Table 1, a comparison with other Indian studies revealed a variation in the commonest offending aeroallergen in different parts of the country. However, the observations of our study were similar to Gowda et al¹⁰ carried out in the Bangalore region.

Table 1.

Comparison of aeroallergen sensitization with other studies based on geographic location.

	Patients studied (n)	Region	Dust mite	Pollen (%)	Insects (%)	Animal dander (%)	Fungi (%)
Gowda et al10	486	Bangalore	44.65	6.15	2.11	1.23	1.72
Prasad et al16	48	Lucknow	12	7.8	21.2	3.1	1.3
Kumar et al17	918	Delhi	12.42	14.88	43.9	Not done	11.98
Shyna KP et al14	60	North Kerala	33	10	25	13.35	16.6
Chogtu et al 15	2219	Udupi	24.21	20.57	22.45	Not done	13.92
Present study	400	Bangalore	41	17.8	Not done	Not done	5.9

Discussion

There are very limited studies carried out in India that comment on the aeroallergen sensitization patterns. The offending allergens vary with the difference in geographical location, altitudes, and climate. Therefore, it is impractical to use similar avoidance measures all over the country. Lack of knowledge of the offending allergen results in unnecessary medication, deterioration in QoL, and adds to the burden on the health care system.

The present study was designed to determine the allergen sensitivity patterns in Bangalore. It was a cross-sectional descriptive study among patients undergoing SPT among patients of allergic rhinitis and/or bronchial asthma.

The patients were selected on a clinical basis, as per the criteria of ARIA guidelines. The pattern of sensitization to aeroallergens was carried out using a customized panel of aeroallergens keeping into consideration the commonly offending aeroallergens of the Bangalore region.

Reliability of the test

Among the study population of 400 patients, 393 patients (98.25%) were positive with the histamine, which was taken as a positive control. The remaining 7 (1.75%) were negative with histamine as therefore were excluded out of the study for analysis of the results. In the current study, 58.02% were noted to have a sensitized with the selected panel of allergens.

A meta-analysis on the diagnostic accuracy of SPT has shown that the pooled estimate of sensitivity and specificity for SPT was 85 % and 77%, respectively.¹¹ SPT, therefore, is fairly accurate for detecting offending allergen in allergic disorders.

The pattern of aeroallergen sensitization varies depending upon the geographical location. The variation in the prevalence of aeroallergen reactivities in a different region is due to different geo-climatic conditions and adaptation of specific microbiological flora and fauna in a specific climate.

In our study, the population was not selected from any particular state, geographic, or topographic region. The study population comprised of the population of variable ethnicity who were residing in Bangalore for at least the last 12 months. The subjects varied in their native origin, age, genetic predisposition, dietary habits, hygiene habits, different allergen exposure, and sensitization. The chances of exposure and sensitization to the allergens present in the Bangalore region were similar to all individuals. The selection bias is, therefore, eliminated, assuming that all the subjects were at an equal risk of aeroallergen exposure. It also implies that the subjects belonging to different ethnicity had variable genetic predisposition, variable dietary patterns, different immunogenic susceptibility. It could thus be considered that the study population represented a subset of the Indian population.

House dust mites sensitization was commonest among the offending aeroallergens found in our study, which is consistent with other studies, as well involving individuals with airway allergies (Mumbai - western part of India - 77.13%, Allahabad - Northern part of India - 60% and North Kerala – Southern part of India −70%).^12,13,14

SPT carries the advantage of easy to perform, quick, and reproducible results that can be visually perceived by the patient. SPT is, therefore, recommended for identification of the offending aeroallergens. It is the gold standard for allergic conditions and bears a good accuracy due to clinically visible reaction as a result of an antigen–antibody interaction, unlike RAST that is a quantitative assessment of the bound IgE in serum. However, the variability in the accuracy of these tests across studies can be explained by lack of standardization, stability, and composition of allergens, the testing device, the patient population, the quality of study design, the color of skin, or skin reactivity. Despite these limitations, the skin prick test remains to be fairly accurate.

In our study of aeroallergen sensitization in an adult population residing in the Bangalore region and suffering from allergic rhinitis ± bronchial asthma, the commonest aeroallergen was found to be house dust mites (41%) - D. pteronyssinus (36.9%) and D. farinae (22.4%). Pollen (17.8%) aeroallergen sensitization was the second commonest, followed by Fungi (5.9%) aeroallergen sensitization. Avoidance for the dust mites, pollens, and fungi may result in improvement of symptoms in allergic patients. This study has helped in detecting the aeroallergen that will also help in streamlining the treatment for immunotherapy in this area.

Conclusion

Allergic rhinitis is the most common form of allergy encountered worldwide and is a leading chronic condition affecting pediatric and adult population leading to the deterioration of the quality of life. The condition is on the rise. The selected population in our study was phenotypically the same, was residing in Bangalore but was pooled in differentially from various states and origins of India. This implies there was no selection bias, and the chances of exposure and sensitization to the exposed allergens were similar to all individuals.

In our study, we showed the importance of house dust mites, pollens, and fungi, sensitizing aeroallergens in patients with allergic rhinitis and/or bronchial asthma in the Bangalore region. Correct identification of offending aeroallergen reduces the overuse of antihistaminics and streamlines the management to individualized treatment, avoidance of allergens, and appropriate immunotherapy. Avoidance for the dust mites, pollens, and fungi may result in improvement of symptoms in allergic patients. This study has helped in detecting the aeroallergen that will also help in streamlining the treatment for targeted immunotherapy in this area.

We recommend SPT in diagnosis of AR owing to its ease of administration, producing quick results that can be visually perceived by the patient and make it simple to counsel the patient. It has high sensitivity and specificity and is the gold standard. It carries a more meaningful assessment since it gives a reaction due to allergen combining with the free IgE in the serum, unlike RAST that is a quantitative value of the bound serum IgE.

In this study of 400 patients of allergic rhinitis and/or bronchial asthma, the prevalent aeroallergens in the Bangalore region were determined using the SPT. The commonest aeroallergen sensitization was found to be house dust mites (41%) – D. pteronyssinus (36.9%), and D. farinae (22.4%). Pollen aeroallergen sensitization (17.8%) was the second commonest, followed by Fungi aeroallergen sensitization (5.9%).

Limitations

Our study was a descriptive study, and hence all patients were tested with the same predetermined allergen panel. Allergen extracts selected were on the basis of sensitization patterns noted to be offending in the Bangalore region, as reported in previous studies.

Hence it is assumed that it may not have been able to capture any new emergent allergen sensitizations. Also, the sensitization patterns have been noted cumulatively among the patients attending allergy clinic, and segregation of allergic rhinitis, bronchial asthma, and allergic rhinitis with bronchial asthma groups has not been done.

Disclosure of competing interest

The authors have none to declare.