Sex differences in comorbidities and mortality risk among patients with chronic obstructive pulmonary disease: a study based on NHANES data

Background Patients with chronic obstructive pulmonary disease (COPD) commonly have coexisting comorbidities that contribute to higher exacerbation frequency, poorer health status, and increased all-cause mortality; however, there are only a few studies available on the sex discrepancy in the comorbidity distribution and outcomes among COPD patients, and there is limited information about the discrepancy in all-cause mortality between men and women. Methods Based on data from the U.S. National Health and Nutrition Examination Survey conducted between 2007 and 2012, we compared participants aged 40–79 years with spirometry-defined COPD to compare the prevalence of comorbidities between men and women. The survival of the subjects was documented, and the sex discrepancy was determined using Kaplan–Meier analysis. Comorbidities and all-cause mortality were analyzed by using a Cox proportional hazards model to determine their strength of association in different sex groups. Results Compared to men, women had a significantly higher prevalence of asthma (OR 1.93, 95% CI 1.46 to 2.57, p < 0.001) and arthritis (OR 1.77, 95% CI 1.39 to 2.24, p < 0.001). Women had a significantly lower prevalence of coronary heart disease (OR 0.48, 95% CI 0.27 to 0.87, p = 0.015) and gout (OR 0.42, 95% CI 0.25 to 0.67, p = 0.001). Kaplan–Meier analysis revealed that compared with that of the female group, the survival rate of the male group was significantly lower (p < 0.001). Among men, the presence of anemia (HR 2.38, [95% CI 1.52–3.73], p < 0.001), gout (HR 1.55, [95% CI 1.04–2.30], p = 0.029) and congestive heart failure comorbidities (HR 1.85, [95% CI 1.12–3.04] p = 0.016) was associated with a higher risk of mortality; among women, the presence of anemia (HR 2.21, [95% CI 1.17–4.20], p = 0.015) and stroke (HR 2.04, [95% CI 1.07–3.88], p = 0.031) comorbidities was associated with a higher risk of mortality after adjusting for age, race/Hispanic status, BMI, smoking status, FEV1% predicted and prevalent comorbidities. Conclusions COPD-related comorbidities and all-cause mortality were discrepant between men and women, and men had poorer survival than women in the nationally representative data that were analyzed.