Abstract: Objective To analyze the epidemiological characteristics of comorbidities in chronic obstructive pulmonary disease (COPD) and to investigate their association with exercise tolerance and symptom burden. Methods This study included patients diagnosed with COPD at the Xinhua Hospital of the Huainan Xinhua Medical Group between January 2022 and December 2024. A self-administered questionnaire was used to collect data on patient demographics, lifestyle, and behavioral habits. Comorbidities were defined according to the International Classification of Diseases, Tenth Revision (ICD-10). Exercise tolerance was assessed using the 6-Minute Walk Test (6MWT), and symptom burden was evaluated with the COPD Assessment Test (CAT) and the modified Medical Research Council (mMRC) dyspnea scale. A point-biserial correlation analysis was performed to determine the relationship between comorbidities and measures of exercise tolerance and symptom burden. Results Of the 506 COPD patients included, 415 (82.02%) presented with at least one comorbidity. The prevalence of comorbidities was significantly higher in males (88.82%) compared to females (71.78%) (P<0.01). The three most prevalent comorbidities were hypertension (n=289, 57.11%), ischemic heart disease (n=165, 32.61%), and bronchiectasis (n=117, 23.12%). The comorbid group had a mean age of 61.25±7.73 years, a longer disease duration, and included 40 patients (9.64%) classified as GOLD stage 4. In the comorbid group, 240 patients (57.83%) had a 6MWT distance of less than 150 meters, 203 patients (48.92%) had a CAT score between 21 and 30, and 212 patients (51.08%) were at mMRC grade 3. In contrast, within the non-comorbid group, 84 patients (92.31%) achieved a 6MWT distance between 150 and 450 meters, 43 patients (47.25%) had CAT scores in the 21-30 range, and 35 patients (38.46%) were at mMRC grade 2. The 6MWT was negatively correlated with the presence of comorbidities (r=-0.327, P<0.01), while CAT and mMRC scores were positively correlated with comorbidities (r=0.210 and r=0.223, respectively; both P<0.01). Conclusions Comorbidity is highly prevalent among patients with COPD and exhibits a gender-based disparity. The presence of comorbidities adversely affects patients' exercise tolerance and increases their symptom burden. These findings underscore the necessity for chronic disease management strategies to prioritize the management of comorbidities to improve patient quality of life.

Key words: Chronic obstructive pulmonary disease, Comorbidity, Symptom burden, COPD assessment test (CAT), Modified medical research council scale (mMRC)