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.