INDACO project: COPD and link between comorbidities, lung function and inhalation therapy

Chronic Obstructive Pulmonary Disease (COPD) is characterized by respiratory and extrarespiratory components referring both to systemic complications of COPD, like skeletal muscle myopathy, weight loss and others, and frequently associated comorbidities, interesting various organs and systems (cardiovascular diseases, malignancies, osteoporosis, diabetes, etc.). These comorbidities may increase the rate of hospitalization of COPD patients and have a huge effect on the outcomes of the respiratory disease. Inhalation therapy of COPD with bronchodilators and steroid is primary driven by airflow obstruction, symptoms like dyspnoea, and acute exacerbations. INDACO project has been developed in 2013 to assess the prevalence and type of comorbidities in COPD patients referred to the outpatient wards of some hospitals in Central and South Italy and a preliminary report has recently been published. In the present study, after widening that database, we evaluate the prevalence of comorbidities and the relationships between comorbidities and sex, age, symptoms, lung function and inhalation therapy in COPD patients.

In each enrolled patient, anthropometric and anamnestic data, smoking habits, respiratory function, GOLD (Global initiative for Chronic Obstructive Lung Disease) severity stage, Body Mass Index (BMI), number of acute COPD exacerbations in previous years, presence and type of comorbidities, and the Charlson Comorbidity Index (CCI) were recorded.

We collected data of 569 patients (395 males and 174 females, mean age 73 ± 8.5 yrs). The prevalence of patients with comorbidities was 81.2%. Overall number of comorbidities was not related to airflow obstruction and age, but to acute exacerbation of COPD, dyspnoea measured with MRC scale, and male gender. A subgroup analysis revealed that ischaemic heart disease was predominant in males, whereas mood disorders in females. The use of a more complex (multi-drug) inhalation therapy was related with bronchial obstruction measured by FEV₁/FVC (p for trend = 0.003) and number of comorbidities (p for trend = 0.001). In multivariate analysis, only airflow obstruction and number of comorbidities were determinant of complexity of therapy, but not MRC and acute exacerbation of COPD. However, the statistical model reached an extreme low degree of significance (r^2 = 0.07).

Our study showed a high prevalence of comorbidities in COPD, with some differences related to gender. Number of comorbidities and airflow obstruction represent the determinant of inhalation therapy prescription. Dyspnoea and acute exacerbation of COPD, unlikely suggested by guidelines, are not significant drivers of therapy in the real life setting of our study.