Proportion of Allergic Bronchopulmonary Aspergillosis Presenting as Difficult-to-control Asthma in Patients Attending a Tertiary Care Centre using the Modified ISHAM Criteria: A Cross-sectional Study

Introduction: Difficult-to-control asthmatics, as defined by the Global Initiative for Management of Asthma (GINA), belong to a subset of patients whose symptoms remain uncontrolled despite adhering to maximal optimised therapy. Complex hypersensitivity reactions in response to airway colonization with Aspergillus fumigatus, which occurs in patients with asthma or cystic fibrosis, are established factors for a poor response to treatment and frequent exacerbations. Only limited data related to Allergic Bronchopulmonary Aspergillosis (ABPA) is available from India, particularly from Kerala. Aim: To assess the occurrence of ABPA in patients with difficult to-control asthma using the modified ISHAM criteria. Materials and Methods: This cross-sectional analysis was conducted in the Department of Pulmonary Medicine, Institute of Chest Diseases, Government Medical College, Kozhikode, Kerala, India from February 2019 to July 2020. The study population comprised asthmatics attending the Pulmonary Medicine Outpatient Services who were on regular medications, including optimal doses of inhaled corticosteroid and long acting beta-agonist combinations. Patients with two or more exacerbations per year requiring systemic steroids for symptom control and a positive skin test for Aspergillus fumigatus antigen were further analysed using the modified International Society for Human and Animal Mycology (IHAM) criteria to determine the proportion of difficult-to-control asthmatics with ABPA. A total of 185 subjects were enrolled. Twelve patients opted out of the study, and the remaining 173 patients were screened using the modified ISHAM criteria. Statistical analysis was performed using Stastistical Packages of Social Sciences (SPSS) software version 21.0. Continuous parameters were expressed as mean and median, while categorical parameters were measured as frequency and percentages. Results: It was observed that 104 (60.1%) patients belonged to the age group between 41-60 years, while approximately 60 patients (34.7%) were below 40 years of age. Among the 173 patients, 86 (49.7%) tested positive for Aspergillus fumigatus antigen. Applying the ISHAM criteria, it was found that only 17 (9.8%) of these patients satisfied the criteria for co-existent ABPA. A total of 101 patients (58.4%) required at least one hospital admission, while 4 (2.3%) patients required more than three hospital admissions per year. Total 21 (12.1%) patients had IgE specific to Aspergillus fumigatus, while total IgE levels were elevated in 46 (26.6%) cases. Thirty-six cases (20.8%) had a high peripheral eosinophil count Conclusion: This study suggests the possibility of the treating physician overlooking 10% of asthmatics in this region who are being managed as difficult-to-control asthma, but who have co-existent ABPA. This subset should be identified early in the course and managed separately for better treatment response.