Background:
Several parameters have been proposed as risk factors for hospitalization of patients with chronic obstructive pulmonary disease (COPD).

Objectives:
The aim of this study was to investigate the association between changes in parameters expressing various different aspects of disease severity and the frequency of hospitalization of patients with severe COPD without co-morbidities.

Population and Methods:
Of 117 patients with severe COPD recruited for prospective study, 74 completed 2-year monitoring and were classified into 2 groups according to their frequency of hospitalization: Group A (n=39) ≤2 hospitalizations/year, Group B >2 hospitalizations/year (n=35). Parameters measured at baseline and 2 years included: FEV₁ % pred, FEV₁/FVC ratio, ratio of inspiratory capacity (IC) to total lung capacity (TLC)(IC/TLC), body mass index (BMI), fat free mass index (FFMI), 6 minute walk distance (6MWD), the Borg dyspnoea scale before and after 6MWD, dyspnoea according to the Medical Research Council (MRC) scale, pH and 8-isoprostane in exhaled breath condensate (EBC), serum levels of C-reactive protein (CRP) and fibrinogen, arterial blood gases, the BMI, airflow obstruction, dyspnoea, and exercise capacity (BODE) index and quality of life.

Results:
The patients with more frequent hospitalizations showed greater change in the baseline study variables after 2 years. The specific differences were loss of muscle mass, deterioration of airway obstruction, decrease in exercise capacity, increase in airways and systemic inflammation and impairment in quality of life. The most significant changes found to be associated with hospitalization frequency using a regression model were in CRP, 6MWD, fibrinogen, 8-isoprostane and BODE.

Conclusions:
In this selected cohort of patients with severe COPD, increased hospitalization frequency was associated with changes in parameters expressing deterioration in exercise capacity and in systemic and airways inflammation.