Prevalence of Allergic and Non-allergic Asthma in Kumaun Region of Uttarakhand, India: A Cross-sectional Study

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Introduction: Asthma is a heterogenic disease, commonly divided into allergic and nonallergic asthma. It affects people of all age group and is associated with impaired lung function. Previously, it was thought that asthma is a disease of developed countries but at present, world scenario has changed and its prevalence in developing countries is rapidly increasing. Asthma shows large geographical variations in terms of prevalence, severity and mortality. Aim: To establish the prevalence of allergic and nonallergic asthma in adults of Kumaun region of Uttarakhand (India) and to evaluate whether the peripheral blood cell count is associated with the severity of lung impairment in both the subtypes (allergic and nonallergic) of asthma. Materials and Methods: This cross-sectional study was carried out jointly in Department of Physiology and Department of Respiratory Medicine, Government Medical College, Haldwani, Uttarakhand (India), during the period from October 2015 to January 2017. A total of 125 patients of both sexes age above 18 years, who attended the OPD of Respiratory Medicine and diagnosed asthma by the physician were enrolled in the study. The patients associated with tuberculosis, worm infestations, other allergic diseases and systemic diseases were excluded. History of Allergic Rhino-Conjunctivitis (ARC) was used for allergic sensitisation and to define allergic asthma. Classification of severity of airflow limitation was done according to Global Initiative for Asthma (GINA) guidelines. Absolute Leukocyte Counts was determined by using the formula: Absolute leukocyte count=Differential leukocyte count/100×Total leukocyte count. One-way ANOVA followed by Tukey HSD post-hoc analysis and Chi-square was done. Level of statistical significance was set at p-value <0.05. Results: The prevalence of allergic asthma was more in 79 patients (63.2%), in comparison to nonallergic asthma in 46 (36.8%) and it (allergic asthma) was more common in males than females (54:25). Mean age of allergic and nonallergic group asthma patients were 51.00±14.31 and 56.11±13.14 years, respectively. In allergic asthma patients, blood eosinophil count increased significantly (p=0.001) the severity of lung impairment increased and no significant changes were observed in other blood cell counts while in nonallergic asthma over-all neutrophil count was significantly high (p=0.044) with increase in severity. Nonallergic asthma also showed increasing trend of eosinophil count as the severity of airway obstruction increased but there were no significant changes in other counts. Conclusion: The prevalence of allergic asthma is high in comparison to nonallergic asthma among adults of Kumaun region of Uttarakhand, India and it is more prevalent among males in both the groups. Peripheral blood leukocyte count might be used as biological marker to differentiate allergic asthma from nonallergic asthma.