Reproductive Lifespan and Adult-Onset Bronchiectasis in U.S. Postmenopausal Women: An Investigation of the Women's Health Initiative Cohort

BACKGROUND: While bronchiectasis disproportionately affects postmenopausal women, the role of reproductive factors in its pathogenesis is not well characterized. We hypothesized that a shorter reproductive lifespan is associated with higher risk of bronchiectasis. METHODS: We studied postmenopausal women in the Women’s Health Initiative study. The exposures included ages at menarche and menopause, and time between the 2 (reproductive lifespan). The outcome was the first incidence of bronchiectasis after Medicare enrollment, as reflected in the Medicare claims data. Incidence rates were calculated and a series of Cox proportional hazards models controlling for demographics, body mass index, smoking, oophorectomy, hormone therapy (HT), oral contraceptives, and comorbid conditions were created. RESULTS: Cumulative incidence of bronchiectasis in the cohort of 96,996 women was 2.7%. Shorter reproductive lifespan was associated with higher bronchiectasis risk (trend p=0.01). Women with the longest reproductive lifespan (≥40 years) were at 12% lower risk than those with the shortest reproductive lifespan (<30 years; adjusted approximate hazard ratio [aHR]=0.88 [95% confidence interval (CI): 0.77, 0.99]). HT modified this relationship (interaction p=0.04): shorter reproductive lifespan was associated with bronchiectasis risk only in the absence of HT (trend p=0.01). Without HT, women with the reproductive lifespans ≥40 years were at 22% lower risk of bronchiectasis than those with the reproductive lifespans <30 years (aHR=0.78 [95% CI: 0.62, 0.94]). The use of HT was associated with a 19% greater risk of bronchiectasis (p<0.01). CONCLUSION: Longer reproductive lifespan is associated with reduced risk of bronchiectasis in postmenopausal women – but only in those without a history of HT use.