European Journal of Cardiovascular Medicine

Clemens Vonpirquet introduced the term "allergy" in 1906, deriving it from the Greek words "allos," meaning "others," and "ergon," meaning "reaction," to describe hypersensitivity reactions. Allergic rhinitis (AR), an IgE-mediated hypersensitivity disease affecting the mucous membranes of the nasal airway, is characterized by symptoms such as sneezing, itching, watery nasal discharge, and a sensation of nasal obstruction. Allergic respiratory diseases are prevalent among pediatric patients, with allergic rhinitis and asthma being common afflictions of the respiratory tract [1].

Despite its high prevalence, allergic rhinitis, which is a heterogeneous disorder, often goes undiagnosed. Research indicates that allergic rhinitis is the most common chronic disorder among pediatric populations, affecting up to 40% of children. It represents one of the most prevalent chronic conditions in developing countries, significantly impacting quality of life. Allergic rhinitis disrupts sleep patterns in children, leading to daytime fatigue and sleepiness, and it is also considered a risk factor for sleep-disordered breathing. The condition contributes to increased school absenteeism and interferes with concentration during class hours. Allergic rhinitis involves inflammation of the mucous membranes of various respiratory structures, including the nose, eyes, eustachian tubes, middle ear, sinuses, and pharynx. Eosinophilia, observed either in blood or tissue, is associated with allergic rhinitis [2].

A combination of history-taking, clinical examination, skin prick testing, radioallergosorbent assay for specific IgE levels, and nasal smear for eosinophils can aid in diagnosing most cases of allergic rhinitis. There is growing evidence implicating eosinophils in the pathophysiology of allergic respiratory diseases. Airborne allergens and irritants directly stimulate mast cells to produce IgE and cytokines, which further enhance eosinophilic infiltration in allergic diseases. The presence of eosinophil leukocytes within nasal and bronchial mucosa, along with eosinophilia in nasal secretions, sputum, and blood, is commonly observed in atopic populations [3].

In settings where IgE estimation and allergy tests are unavailable, confirming allergens as the etiological agents can be challenging. Normal nasal eosinophil percentages typically range from 0 to 6% (<10), while the normal absolute eosinophil count is considered to be <450 cells/microliter [4-6]. This study aimed to assess the value of nasal smear eosinophil counts as a simple, noninvasive, and cost-effective method for diagnosing allergic rhinitis.

This study was conducted prospectively in a hospital setting and included 123 pediatric patients diagnosed with allergic rhinitis. Participants were recruited from the pediatric outpatient department of a tertiary level care medical institute.

All children aged 2 to 18 years displaying signs and symptoms of allergic rhinitis, as documented in a specifically designed proforma for this study, were included in the study. Children with tuberculosis, recurrent or chronic pneumonia, malignancies, collagen vascular disorders, or those receiving oral/nasal steroid therapy were excluded from participation.

Nasal secretions were obtained by instructing the child to blow their nose onto a plastic wrap, which was then transferred onto a glass slide. In cases where this method was not feasible or sufficient secretion was not obtained, a cotton-tipped swab was inserted into a nostril for 60 seconds. The collected nasal secretion was transferred to a glass slide, spread out, and allowed to air dry. The normal nasal eosinophil percentage was defined as 0-6% (<10).

Blood samples were collected with strict aseptic measures through venepuncture, with 3 ml of blood collected in Ethylene Diamine Tetra Acetic Acid (EDTA) anticoagulant tubes. Absolute eosinophil count (AEC) was determined from the blood sample, with a normal absolute eosinophil count considered to be <450 cells/microliter.

Table 1 illustrates that the most prevalent age group in the study was 6 to 10 years, closely followed by the 11 to 15 years age bracket. The mean age of the patients was calculated to be 10.5 ± 2.88 years. The male-to-female ratio was observed to be 1.12:1. Notably, the highest incidence of allergic rhinitis was observed in children aged 6 to 10 years, accounting for 54.10% of cases.

In Table 2, the common risk factors among the subjects were assessed, revealing seasonal changes, pollen allergy, positive family history, and animal allergens as the predominant factors.

Table 3 highlights the most common presenting complaints among the subjects, with running nose and nasal obstruction being the predominant symptoms, followed by itching/sneezing, epistaxis, and cough. Additionally, bronchial asthma emerged as the most prevalent comorbidity among the subjects.

Table 4 sets a cutoff of 10 eosinophils per high-power field for eosinophil count analysis. It was found that 76.42% of the subjects exhibited eosinophil counts exceeding 10 cells/hpf [p = <0.05]. Furthermore, a positive albeit weak correlation coefficient was observed between nasal eosinophil and blood eosinophil levels [r=0.22, p = <0.05]..

Table 1: Age and gender wise distribution of cases of AR

Table 2: Risk factors among cases of AR

Table 3: Presenting symptoms among cases of AR

Table 4: Nasal Smear Eosinophils and blood AEC in study population

Allergic rhinitis represents a prevalent condition among pediatric patients attending outpatient departments in clinical settings. Diagnosis primarily relies on a thorough history-taking and clinical examination, with routine investigations often providing limited diagnostic value. Confirming the allergic etiology of the disease may necessitate complex tests such as skin hypersensitivity testing, Radio Allergo Sorbent Test (RAST), enzyme-linked immunosorbent assay (ELISA), and IgE assay, which are not always feasible for all patients. Therefore, this study aimed to assess the practicality of nasal eosinophil counts compared to blood eosinophil counts in children with allergic rhinitis.

The study revealed a nearly equal distribution of allergic rhinitis among genders, consistent with findings by Venkateswarlu V et al [7]. Seasonal variation emerged as the most common risk factor, followed by pollen allergens. Notably, food allergy did not exhibit statistical significance, consistent with findings from Pokharel PK et al [8].

Running nose was the predominant symptom, observed in 80% of cases, followed by nasal obstruction, aligning with results from studies by Shetty SS et al and Kumar N et al [9,10]. Nasal eosinophil counts exceeding 10 cells/hpf, as per recommendations by the Indian Academy of Pediatrics (IAP), were considered positive in this study. Similar cutoff values have been adopted by other researchers, such as Crobach M et al [11]. Additionally, a blood eosinophil count exceeding 440 cell/mm3 was deemed significant in the present study, consistent with findings by Chowdary VS et al [12].

Various studies have reported varying rates of nasal smear eosinophilia, ranging from 18.0% to 80.0%. Similar findings were observed in studies conducted by Sanil A et al and Kumar N et al, where nasal smear eosinophilia was reported at 57% [13-16].

Children who present with symptoms such as nasal discharge, nasal obstruction, or itching/sneezing should undergo evaluation for allergic rhinitis. Nasal eosinophil count can serve as a predictor, albeit weak, of blood eosinophil count, and a robust predictor of allergic rhinitis.

1. Skoner DP. Allergic rhinitis: Definition, epidemiology, pathophysiology, detection and diagnosis. J Allergy Clin Immunol. 2001 Jul;108(1 Suppl):S2-S8.
2. Bousquet J, Khaltaev N, Cruz AA, Denburg J, Fokkens WJ, Togias A, et al. Allergic Rhinitis and its Impact on Asthma (ARIA) 2008 update (in collaboration with the World Health Organization, GA2LEN and AllerGen). Allergy. 2008;63(Suppl 86):8-160.
3. Sandhya V, Ranganath KR, Madhusudan SR, Prabhavathi R. Comparative Study Between Nasal Smear Eosinophilia And Absolute Eosinophilic Count In Children With Allergic Rhinitis. Eur J Mol Clin Med. 2022;9(4):1617-1621.
4. Sonawanel R, Ahire N, Patil S, Korde A. Study of Eosinophil Count in Nasal and Blood Smear in Allergic Respiratory Diseases. J Med Sci. 2016;3(1):44-51.
5. Kumar N, Bylappa MS, Ramesh AC, Reddy A. A study of eosinophil count in nasal and blood smear in allergic respiratory diseases in a rural setup. J Med Update. 2012 Jan;7(1):40-6.
6. Jáuregui I, Mullol J, Dávila I, Ferrer M, Bartra J, del Cuvillo A, Montoro J, Sastre J, Valero A. Allergic rhinitis and school performance. J Investig Allergol Clin Immunol. 2009;19(Suppl 1):32-9.
7. Venkateswarlu V, Mohan M KV. A comparative study of nasal smear eosinophilia v/s absolute eosinophilic count in patients with allergic rhinitis. MRIMS J Health Sci. 2015; 3(1):36-8.
8. Pokharel PK, Pokharel P, Bhatia NK, Pandey RM, Erkki K. Asthma symptomatic school children of Sonapur. Kathmandu Univ Med J. 2007; 5(4):484-7.
9. Kumar N, Bylappa K, Ramesh AC, Swetha R. A study of eosinophil count in the nasal and blood smear in allergic respiratory diseases in a rural setup. Internet J Med Update. 2012; 7(1):40-6.
10. Shetty SS, Rai S, Somayaji GKS, Ali. Nasal smear eosinophil count vs AEC of patients diagnosed with allergic rhinitis attending a tertiary care hospital and the effect of treatment with a topical steroid nasal spray. J Dent Med Sci. 2014; 13(1):7-2