The present study was of cross-sectional nature conducted in out-patients attending the Department of Pulmonary Medicine with a diagnosis of asthma as per GINA guidelines. The study was approved by institution ethics committee, NO: RAJH 18006. Patients above seven years with features of asthma were included in the study. The Asthma severity was assessed using the ACT questionnaire [Annexure 1] and lung function studies. Any patient with an ACT score less than 20 and FEV1 value less than 80 were defined as poorly controlled asthma [7-9]. All the patients were residents of central part of Kerala. The study was conducted from January 2018-May 2018. Any patient less than seven years of age, patients with inability to perform an acceptable pulmonary function test, and subjects with active upper limb dermatitis or truncal dermatitis precluding a SPT were excluded from the study. Informed consent was obtained from all the subjects.

After detailed clinical examination, complete blood count, S. IgE levels, chest radiograph and pulmonary function test were performed. From this group, all subjects with a diagnosis of asthma as per study definition, in whom SPT was done were included in the study. SPT was done using 38 allergens in aero and food allergen panels. The antigens were obtained from Merck AllergoPharma, Germany which included two types of dust mite, five varieties of grass and pollen each, fungal antigens, dander.

After thorough cleaning both upper limbs the test sites were marked and numbered from 1 to 38. About 0.1 mL of each allergens were dropped to the concerned sites using dropper. Then using a skin prick lancet the allergens were pricked through the skin. The area was kept undisturbed for 20 to 30 minutes. The results were read after this period. First to see the histamine and normal saline induration which were used as positive and negative controls. Then the induration corresponding to each allergen is measured and recorded. Any induration more than 3 mm was taken as significant.

All the statistical analysis were done with SPSS software version 25. A Chi-square test was used to compare the data. A Spearman’s rank correlation was run to determine the relationship between FEV1 and ACT values. A p-value of less than 0.05 was considered as significant.

A total of 187 patients meeting the inclusion criteria were included in the study. A total of 7106 SPT were done in them. Average age of the study group was 29 years. The [Table/Fig-1] shows number of patients in each age group. Almost equal number of males and females were enrolled into the study (93 male patients and 94 female patients). Average IgE level in the study population was 1099. Most of the patients showed positive reactions to multiple allergens. Allergens that had a high occurrence of sensitisation in the study subjects include house dust mite (72%), Aspergillus fumigatus (45%), mugwort (37% etc.,). [Table/Fig-2,3] summarises the prevalence of allergen sensitivity in the study group. Most of the patients showed erythema and induration, but formation of pseudopodia and indurations more than 15 mm were observed in 6 patients. Patients with features of inadequately controlled asthma (ACT score less than 20 and FEV1 less than 80 % predicted) showed a higher occurrence of positive reaction in the SPT as compared with those having good ACT score and FEV1 >80%. When we compared the allergen sensitivity among patients with FEV1 <80 and FEV1 >80, we found that all patients (100%, N=107) with low FEV1 having sensitivity to one or another aeroallergen as compared to 33.75% (N=27) in good FEV1 group. The allergen sensitivity among patients with good and poor ACT score also showed a significant difference. It was noticed that all 116 patients with low ACT score showed an allergen sensitivity as compared to 25.3 % (N=18) patient with good ACT score. A Chi square test was used to compare the data. All these differences were statistically significant with a p-value of less than 0.0001. A Spearman’s rank correlation was run to determine the relationship between 187 patient’s FEV 1 and ACT values. There was a weak, positive correlation between FEV 1 and ACT values, which was statistically not significant (r=0.065, p=0.375).

The test was extremely safe in all subjects and no serious adverse events were reported. None of the patients tested reported any adverse reaction except local itching. No systemic allergic features or anaphylactic reactions occurred and no subjects required any injectable medications in the 12 hour post-test period.

Atopy refers to an inherited tendency to mount IgE antibodies mediated allergic response to small amounts of common environmental protein. Common sites of manifestation of allergic disorders include upper and lower respiratory tract, skin, eyes etc., among other. Skin prick test offers the most convenient method of identifying the culprit antigen. All patients who were subjected to SPT in the present study had reaction to at least one aeroallergen tested. This is in agreement with previously published studies. Giridhar BH et al., reported 87.5%1 and Rao P et al., described 80% sensitivity to at least one antigen [10,11].

A previous study conducted in Lucknow [12] in patients with nasobronchial allergy revealed that the common offending allergens were insects (21.2%), followed by dusts (12.0%), pollens (7.8%), animal dander (3.1%), and fungi (1.3%). Another study conducted in the same geographic territory (Central Kerala) had similar results [13]. Housefly, rice grain dust and insect allergen were the common aeroallergen observed. Prawn was the most common food allergen identified. Regional variation do exists with regard to the allergens as well as pattern of clinical presentation.

Previous research has found that cockroach exposure and sensitivity are more prevalent in the inner-cities of the Northeast United States, and its effect on asthma morbidity can be greater than other household allergens, such as dust mite or pet dander [14,15]. Haselkorn T et al., recognized predictors of severe exacerbations in children and found that patients with 3 to 4 allergic triggers (from pollen, dust, pets and mould) were at 2 fold greater risk of future asthma exacerbation in comparison to those with no allergic triggers [16].

Our study revealed significant number of patients with inadequately controlled asthma have sensitization to grass pollens like mugwort (Artemisia vulgaris) and ragweed (Ambrosia). But previous many studies have shown that pollen such as Artemisia vulgaris and Ambrosia artemisifoliais are commonly associated with upper airway allergies. These two plants got a larger sized allergen compared with other aeroallergens including house dust mites. Due to its size and aerodynamic properties, they are mainly deposited in the upper airway and induces local inflammatory or pathological changes [17,18]. An inadequately controlled upper airway allergy could be led to a lower airway changes would be a possible explanation. The enzymatic activity of Dermatophagoides pteronyssinus mites seems to be important in the pathogenicity of lower airway and systemic inflammations [19].

We identified in addition to HDM and grass pollens fungal group of allergens also poses an important role in causing allergy and it affects the therapy also. Fungal agents according to their spore sizes cause either upper airway or lower airway allergy or sometimes both [20]. The major fungal agents detected in our study were Aspergillus, Cladosporum, Alternaria and Rhizopus.

Almost all patients were having one or another form of allergen sensitivity. As per GINA guidelines for asthma control allergen immune therapy against house dust mite has been recommended along with pharmacotherapy. Apart from conventional management strategies a small subset of these patients may benefit from immunotherapy to fungal agents and grass pollens too, apart from house dust mite. So efforts must be taken to identify allergen sensitivity in those patients with inadequately controlled asthma actively and an individualised allergen desensitisation protocol must be considered in each patient along with pharmacotherapy. Proper weed and environmental control and inclusion of these agents too in the immuno therapy should be practised routinely.

Considering the importance of aeroallergens in the pathogenesis of asthma, the present study used a limited number of aeroallergen panel than previously conducted similar studies. The allergen panel did not have insect allergens which might have implications in the geographic location of the study. The study did not encounter even a single case of systemic allergic reaction. This probably due to the fact that the allergens used in current study has substantially more purified allergens. Further, SPT results were not correlated with specific IgE allergens by RAST.

House dust mite, fungal allergens and grass pollens were the common allergen sensitisation identified in subjects with poorly controlled asthma in the present study. A correlation was seen between inadequately controlled asthma and sensitisation to multiple aeroallergens. So vigorous allergen screening, weed control and allergen immunotherapy must be included in the management protocol of asthma.