Kaplan-Meier plot of age of death for subjects with sickle cell anemia and asthma (n = 138) and those without asthma (n = 25), conditional on survival beyond age 5 years.
 Reprinted with permission from Boyd JH et al. Asthma is associated with increased mortality in individuals with sickle cell anemia. Haematologica. 2007;92:1115–1118.¹⁰