progression of cystic fibrosis and long-term survival is significantly worse for females than males, especially among individuals diagnosed in childhood [64] . Females with COPD report worse symptoms, lower exercise capacity, more airway hyper-responsiveness and worse health-related quality of life than males [65, 66] . Although morbidity from these conditions may be worse in females, mortality -both from all causes and from respiratory-related disease alone -is still higher in males with COPD [65] , illustrating the complexities involved in assessing the significance of sex and gender for a particular co-morbidity.