Fig. 2
From: A systematic literature review of frequency of vaso-occlusive crises in sickle cell disease
Reported frequency of VOCs by study design, patient age group, and sample size. The vertical axis represents the reported frequency of VOCs in the real world. The horizontal axis represents the study design type. The color of the circular data point represents the age group of the patient population. The size of the circular data point represents the patient population size. Median age is reported where indicated (a), otherwise mean age is reported