|Year : 2022 | Volume
| Issue : 3 | Page : 398-402
Skin prick test in chronic idiopathic urticaria: A retrospective analysis
Sandeep Arora, Satish Chand, Anuj Bhatnagar, Rajeshwari Dabas, Devinder Kumar Suhag, Reetika Pal, Sunmeet Sandhu, Chetan C Patil, Debatraya Paul, Aradhana Rout
Department of Dermatology, Command Hospital Air Force, Bengaluru, Karnataka, India
|Date of Submission||28-Oct-2020|
|Date of Decision||02-Jan-2021|
|Date of Acceptance||02-Jan-2021|
|Date of Web Publication||29-Dec-2021|
Department of Dermatology, Command Hospital Air Force, Bengaluru - 560 007, Karnataka
Source of Support: None, Conflict of Interest: None
Context: Chronic idiopathic urticaria (CIU) is a common clinical condition with a significant impact on the quality of life of its sufferies. Skin prick test (SPT) is a reliable method to detect the allergens and thereby contributing to diagnose of this Type I hypersensitivity. Aims: The aim of this study is to retrospectively analyze the incidence of positive SPT to various allergens in patients with CIU. Subjects and Methods: The data of patients of CIU who had undergone SPT in the dermatology department of a tertiary hospital during the period from July 1, 2018 to December 31, 2019 were reviewed. Evaluation of their history was done with respect to the possible causes and investigations excluding those with a documented history of anaphylaxis, asthma, atopic dermatitis, and dermographism. The results of SPT performed with a battery of 40 allergens (22 aeroallergens and 18 food allergens) obtained from Allergo SPT (Merck specialty Pvt. Ltd., Allergopharma, Darmstadt, Germany), were retrieved and analyzed. Statistical Analysis Used: The data of the 38 patients with CIU who had undergone SPT was entered in Microsoft Excel (MS Office 2016) and then analyzed with descriptive statistics. Results: Overall SPT positivity of these 38 patients was 73.68% and that to food allergens (10.53%), aeroallergens (26.31%), and both aero and food allergens (36.84%). Conclusions: Our study unlike earlier reports in literature ruled out those with clinical as well as laboratory evidence of a topic, disorders which secondarily cause urticaria, thus emphasizing SPT to be an important add-on diagnostic tool even in those cases of CIU which have no obvious exacerbating factors. A significant number of CIU patients of our study showed sensitivity to house dust mite, molds, pollen, food items, and animal epithelia on SPT.
Keywords: Allergen, chronic idiopathic urticaria, sensitization, skin prick test
|How to cite this article:|
Arora S, Chand S, Bhatnagar A, Dabas R, Suhag DK, Pal R, Sandhu S, Patil CC, Paul D, Rout A. Skin prick test in chronic idiopathic urticaria: A retrospective analysis. Med J DY Patil Vidyapeeth 2022;15:398-402
|How to cite this URL:|
Arora S, Chand S, Bhatnagar A, Dabas R, Suhag DK, Pal R, Sandhu S, Patil CC, Paul D, Rout A. Skin prick test in chronic idiopathic urticaria: A retrospective analysis. Med J DY Patil Vidyapeeth [serial online] 2022 [cited 2022 May 21];15:398-402. Available from: https://www.mjdrdypv.org/text.asp?2022/15/3/398/334171
| Introduction|| |
Chronic urticaria (CU) is a common skin disorder which can be quite disabling, significantly impacting on the quality of life of patients by interfering with their day-to-day activities. The reported lifetime prevalence of CU is 1.8%. Its worldwide incidence is 0.1%–3% of the population with women affected twice than men. Chronic idiopathic urticaria (CIU) is diagnosed when an etiological factor accounting for the majority of episodes cannot be elicited on history, physical examination including testing for inducible urticarial, and laboratory evaluation including autoimmune parameters. The occurrence of this is often multifactorial disease even may be determined by exogenous aggravating factors. Patient perception of an allergen as an exacerbating factor needs objective correlation. Skin prick test (SPT) is a reliable and safe tool for detecting the sensitivity to various allergens, which may precipitate or worsen CIU. It is that when the allergen or antigen interacts with specific immunoglobulin E (IgE) fixed to mast cells, histamine, and other chemical mediators are released from them, resulting in the development of a wheal and flare response. There is immune sensitization to food-derived allergens as well as aeroallergens. In some countries, the prevalence of food allergy causing skin wheals is reported to be 6%–8% in children and 2%–3% in adults.
In this study, we retrospectively analyzed the incidence of positive SPT to various allergens in patients with CIU.
| Subjects and Methods|| |
This study is of a retrospective analytical type study; ethical clearance was taken on November 23, 2019, in Command Hospital Air Force Bangalore Ethical Committee (Letter attached). Patients of CSU, who had attended dermatology outpatient department of our institution, were evaluated as per the evaluation protocol for CU. History of anaphylaxis, asthma, atopic dermatitis, and dermatographism was noted. Thereafter, they were investigated to rule out possible systemic or autoimmune causes of CU: Complete hemogram, erythrocyte sedimentation rate, absolute eosinophil count, urine routine and microscopic examination, stool routine and microscopic examination, liver function test, renal function test, hepatitis B surface antigen levels, antihepatitis C virus antibody levels, thyroid profile including thyroid autoantibodies, antinuclear antibody, serum IgE and autologous serum skin test, and clinical tests to exclude physical/spontaneous urticarias were done.
A total of 158 patients of chronic spontaneous urticaria were evaluated as above. Of these, 38 had a noncontributory evaluation profile and underwent SPT. Before SPT, they were advised to stop antihistamines for 3 days and oral corticosteroids, tricyclic antidepressants, and mast cell stabilizers for 1 week. SPT was performed on the volar aspect of both forearms using buffered saline in glycerol base and histamine phosphate 10 mg/ml (provided as a part of the kit) as negative and positive controls, respectively.
The patients were subjected to testing with a battery of 40 allergens: 22 aeroallergens and 18 food allergens (Allergo SPT Kit, Merck specialty Pvt. Ltd., Allergopharma, Darmstadt, Germany) [Table 1]. Resuscitative equipment for anaphylaxis was kept on standby.
SPT was carried out after marking the volar aspect of forearm with a grid as shown in [Figure 1]. Each purified allergen extract was placed on the volar aspect of the forearm after cleansing as a droplet at 2 cm–3 cm intervals and then the sterile lancet was pierced through the droplet perpendicular to the skin so that no blood was drawn out. The results were interpreted after an interval of 20 min. The wheal was measured with a standard ruler if calculating the mean of longitudinal and transverse diameters of the nonconcentric wheals.
To consider the test results as true positive, a positive result of the positive control (histamine) and a negative reaction to the negative control (buffered saline) was taken into account. Reaction of allergen extracts with a wheal diameter of 3 mm or more as compared to the negative control was considered to be positive. The data of the 38 patients with CIU who had undergone SPT were entered in Microsoft Excel (MS Office 2016) and then analyzed with descriptive statistics.
| Results|| |
The mean age of the evaluated 38 patients of CIU was 41.68 years with a range of 20–71 years, and their gender was predominantly female (2.4:1) (27 females and 11 males). The majority of 23 (60.52%) belonged to the age group of 16–45 years. Out of the total number, 24 (63.15%) patients were housewives; nine (23.68%) were general duty soldiers; four (10.52%) were students; and one was a radiographer. The duration of illness in these patients varied from 4 months to 5 years.
The total positive results occurred in 73.68% to both aero and food allergens (36.84%), aeroallergens (26.31%), and food allergens (10.53%), respectively. The most common aeroallergens were mites and pollen (36.84% each), and the major food allergens were milk/eggs and meat (19.44% each) [Table 2].
| Discussion|| |
SPT is a convenient and reliable method of allergy testing with the availability of results in a short duration. Earlier studies have reported positivity of SPT to aeroallergens and food allergens ranging from 27.4% to 82.5% in patients with CU [Table 3], the same 73.68% was in our study [Table 2].
|Table 3: Various studies concerning the incidence of positive skin prick test results in patients with chronic urticaria|
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Different study has reported SPT positivity of CIU ranging from 0.8% to 50%. In our study, SPT positivity to house dust mite (HDM) allergen was 36.84%, most common seven (18.42%) sensitizing allergens being Dermatophagoides pteronyssinus. In a study by Caliskaner et al., SPT positivity to HDMs, D. pteronysinnus, and Dermatophagoides farinae was 24.7% (64/259) and 20.5% (53/259), respectively. In another study, 53% of patients with CU and 79% of them with CU and atopic dermatitis had mite sensitization with 64% (78/122) overall SPT positivity, which suggested that patients with both CU and atopic dermatitis were more likely to be sensitive to HDMs. Oncham et al. reported SPT positivity to HDM in 42.9% (60/140) of patients of CU with highest sensitivity to D. pteronyssinus (50.1%) and D. farinae (32%), whereas SPT positivity in patients of CU with other allergic diseases, namely, asthma and allergic rhinitis was 54.2%.
In CU, the incidence of SPT positivity to pollens has been reported to be between 0.8% and 26.83%. In a study by Krupa Shankar et al. and Sonia Rebello et al. in Karnataka (India), the most common pollens showing SPT positivity were Parthenium, Bermuda grass, Amaranthus, and Cassica., In Thailand, pollen sensitization to Bermuda grass (21.1%) and Timothy grass (13.6%) has been reported. However, in our study, SPT positivity to pollens was reported in 36.84% of patients, and the pollens showing maximum SPT positivity were Plantago lanceolata (13.16%), Artemisia vulgaris (13.16%), Chenopodium album (13.16%), Timothy grass (10.53%), Kentucky bluegrass (10.53%), and Robinia pseudoacacia (7.86%).
Positive SPT to molds in CU has been reported to vary from 0.4% to 12.20%. A study of North Indian population revealed that reaction to fungus was positive in 12.20% of patients, the most common ones being Fusarium solani (7.32%) and Rhizopus nigricans (4.88%), whereas, in a South Indian study, reaction to fungus was positive in 5.2% of patients, and the common allergens were Aspergillus and Rhizopus (2.6% each). In this study, SPT positivity to molds was 21.02%, the major ones being R. nigricans (15.78%) and Helminthosporium halodes (10.52%). Molds are an important source of allergens, in the form of ingested allergens and inhaled spores of aspergillus, Cladosporium, Alternaria, and Penicillium. Sensitivity to these allergens is a common factor in allergic rhinitis and asthma. Earlier studies have implicated the role of fungal allergens in the etiology of CU, but evaluation of sensitivity to molds is difficult because of diversity, uncertain regional distribution, and prolonged period of exposure.
In various Indian studies, the occurrence of animal dander sensitization to dog epithelia (1.3%–12%) and cat epithelia (0%–2%) has been described.,, Whereas, in Thailand population, animal dander sensitization was reported mainly to cat epithelia (12.9%) followed by dog epithelia (10%). In our study, animal dander sensitization was noted with cat epithelia (7.89%). Animal-derived allergens are commonly encountered at home as well as the workplace and allergy to cats, dogs, horses, rabbits, guinea pigs, and mice are frequent in domestic situations and due to occupational exposure.
Studies have variably reported SPT positivity to food allergens ranging from 20.8% to 54.66% in CU. In Indian studies, sensitization has been described with prawn (3.9%–29%), chicken (3.9%–24%), wheat (3.9%-18%), crab (16%), black pepper (13%), masoor dal, almond, ginger, brinjal, rice, chili, milk, banana, and yeast.,,, However, in our study, the most common food allergens were hen's egg (13.16%), wheat flour (10.53%), and chicken (5.26%).
Over the years, various studies done on CU point out toward a definite role of food items in causation or aggravation of CIU. In a study by Moneret-Vautrin, SPT positivity to food allergen in chronic spontaneous urticaria patients was 30% (30/100), also favors the role of a systematic search for food allergens in CSU.
The dissimilarities of positive SPT and the most common sensitizing allergens in this study compared to other studies might be due to diversity of the population (patients are from different parts of the country being an armed forces hospital), their habits, and environmental variation. Moreover, several allergens mentioned in other studies were not part of the Allergo SPT kit used in this study.
| Conclusions|| |
Elimination therapy might play a role in the management of patients with CU, thereby improving their quality of life. More number of studies with a larger cohort and a longer duration are required to assess the clinical relevance of SPT in response to avoidance of suspected allergens.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]