Background: The aim of the study was to analyze the characteristics and survival of a group of patients with COPD according to their clinical phenotype.
Patients and methods: The study population was selected from patients undergoing scheduled spirometry between January 1, 2011 and June 30, 2011 at the respiratory function laboratory of a teaching hospital and comprised those with a previous and confirmed diagnosis of COPD and forced expiratory volume in the first second (FEV1) of <70%. The patients selected were classified into 4 groups: positive bronchodilator response, non-exacerbator, exacerbator with emphysema, and exacerbator with chronic bronchitis. Patients were followed up until April 2017.
Results: We recruited 273 patients, of whom 89% were men. The distribution by phenotype was as follows: non-exacerbator, 47.2%; positive bronchodilator response, 25.8%; exacerbator with chronic bronchitis, 13.8%; and exacerbator with emphysema, 13.0%. A total of 90 patients died during follow-up (32.9%). Taking patients with a positive bronchodilator response as the reference category, the risk factors that were independently associated with death were older age (HR, 1.06; 95% CI, 1.03-1.09), lower FEV1 (HR, 0.98; 95% CI, 0.96-0.99), and exacerbator with chronic bronchitis phenotype (HR, 3.28; 95% CI, 1.53-7.03).
Conclusion: Classification of COPD patients by phenotype makes it possible to identify subgroups with different prognoses. Thus, mortality was greater in exacerbators with chronic bronchitis and lower in those with a positive bronchodilator response.
Keywords: COPD; chronic bronchitis; emphysema; exacerbator; mortality; phenotypes; positive bronchodilator response.