Identification of Frequent Exacerbator Phenotype in Local COPD Patients: Development of Predictive Models for Frequent Exacerbations
Identification of Frequent Exacerbator Phenotype in Local COPD Patients: Development of Predictive Models for Frequent Exacerbations
Tania Ahmed Shakoori1,*, Muhammad Saqib Saeed2, Asif Hanif2, Saima Mukhtar3 and Ayesha Ghauri4
ABSTRACT
Acute exacerbations are important events in the natural history of chronic obstructive pulmonary disease (COPD). Their frequency is directly related to the prognosis of the disease. The objective of this study was to identify the ‘frequent exacerbator’ phenotype and determine the risk factors for increased frequency of acute exacerbations in local chronic obstructive pulmonary disease (COPD) patients in a cross sectional analytical study design. For this purpose 137 patients were included in the study after obtaining necessary permissions from the ethical board of the hospital. COPD was diagnosed on the basis of clinical symptoms and a post bronchodilator values of FEV1/FVC<0.70 on spirometry. Frequent exacerbator’s were defined as patients experiencing 2 or more exacerbation episodes per year, which merited visited to the hospital. Average number of hospital visits for exacerbations per year, smoking history, family history of smoking related chronic lung disease in first degree relatives and presence of comorbidities were recorded from patient history and medical records. Body mass index was calculated and complete pulmonary function tests were recorded using electronic spirometer. Three multiple linear regression models were created with mid maximal expiratory flow, FEV1, and FVC as surrogate markers for lung function in different models. We found that 28 (20.4%) of our COPD patients were frequent exacerbators. All three multiple linear regression models for identifying risk factors for frequent exacerbations were significant (p< 0.001). The model in which mid maximal expiratory flow was used as a surrogate marker for lung function, accounted for the change in the dependent variable to the greatest degree (Adjusted R2= 0.38, p< 0.001). Overall the three models consistently showed that positive family history, high body mass index, heavy smoking, poor lung function (mid maximal expiratory flow/FEF2575, FEV1 and FVC), older age and requirement of steroid therapy predicted increased frequency of exacerbations. To concludelung function (FEF2575%, FEV1 % predicted and FVC% predicted), longer smoking history, higher body mass index, succumbing to COPD at a younger age, and a positive family history of chronic lung disease in first degree relatives are important risk factors for frequent exacerbations of COPD.
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