The associations between comorbidity and exacerbation risk in patients with chronic obstructive pulmonary disease

Objective: To study the association between comorbidity and acute exacerbation risk in patients with chronic obstructive pulmonary disease (COPD). Methods: This was a prospective cohort study with 64 stable COPD patients included. There were 64 males and 18 females with an average age of (68±9) years. Clinical characteristics, the number and type of comorbidities were recorded, and Charlson comorbidity index (CCI) was calculated. The patients were interviewed by phone calls every 3 months since baseline in which the number of acute exacerbations was recorded until 12 months. The impact of CCI, the number of comorbidities and certain comorbidities in the prediction of COPD exacerbation risk were analyzed. Results: Compared to patients with a lower CCI score, patients with a higher CCI score were older (75±6 vs 62±8), and had more severe lung function impairment [FEV(1)%pred: (40±18)% vs (52±18)% ], higher number of comorbidities [4(3, 7) vs 1(1, 3)] and higher frequency of hospital admission due to acute exacerbation [1(0, 2) vs 0(0, 0.25)]. In comparison with patients with lower number of comorbidities, patients with higher number of comorbidities were older (72±7 vs 64±10), and had higher mMRC score [2(1, 3) vs 2(1, 2)] and more severe lung function impairment [FEV(1)%pred: (42±15)% vs (53±19)% ], higher age adjusted CCI score [5(3, 5) vs 3(2, 3) ] and more courses of systemic corticosteroids [2(0, 3) vs 0(0, 0.75)] and/or antibiotics use [3(2, 4) vs 1.5(1, 2.75)]. The number of hospitalizations and total number of exacerbations were higher in COPD patients with bronchiectasis than those without (P<0.005). Conclusion: The inclusion of clinically meaningful comorbidities into the combined assessment of COPD for the prediction of disease prognosis deserves further study.