An Examination of Sex Differences and Cigarette Smoking as Predictors of COPD Prevalence and Incidence in Older US Adults.

Introduction: This study examined the main and interactive effects of sex, cigarette smoking status, cigarette pack-years, and second-hand smoke exposure on COPD prevalence and incidence.

Methods: COPD prevalence was estimated for US adults aged 40+ years from Wave 1 of the Population Assessment of Tobacco and Health Study (n = 12 296). Incidence analyses included adults from the initial sample without a COPD diagnosis (n = 6611). Multivariable Poisson regressions assessed prevalence and incidence based on self-reported sex and cigarette smoking, adjusted for covariates.

Results: COPD prevalence was 7.4% and 9.4% and incident COPD was 5.0% and 8.7% for males and females, respectively. The adjusted prevalence ratio (aPR) for COPD for females was 1.26 [95% CI = 1.11, 1.44], and the adjusted risk ratio (aRR) for incident COPD was 1.73 [1.41, 2.12]. Stratified by smoking status, female (vs. male) sex was associated with aPRs of 1.26 [1.10, 1.44] and 1.35 [0.98, 1.84] and aRRs of 1.32 [1.00, 1.75] and 2.58 [1.79, 3.72] for adults who ever or never smoked, respectively. Smoking status (p = .003) and pack-years (p = .006) increased risk of COPD incidence for both males and females, but to a greater extent for males.

Conclusions: Female sex was associated with significantly higher COPD incidence, which was not explained by cigarette smoking, second-hand smoke exposure, e-cigarette use, or other covariates. Cigarette-related COPD risk factors increased risk of COPD incidence for both males and females but to a greater extent for males. Future research can include examining alternative risk factors or diagnostic biases contributing to higher incident COPD among females.

Implications: Prior studies show that COPD prevalence has been increasing for women in the United States, but the basis for this change remains unclear. This study shows how female (vs. male) sex is associated with significantly increased risk for COPD prevalence and incidence among a nationally representative sample of older (aged ≥40 years) US adults using data from 2013 to 2019, which was not accounted for by cigarette smoking, second-hand smoke exposure, e-cigarette use, or other covariates. Work is needed on alternative COPD risk factors or diagnostic biases contributing to higher incident COPD among females.