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.