Complex sentence: Incidence/Prevalence is said to be 1/5,000 in the United States, however, many cases of eczema are diagnosed as garden-variety atopic eczema without further investigation, so it is possible this figure is misleading.
Split into simpler sentences: Incidence/prevalence is said to be 1/5,000 in the United States. However, many cases of eczema are diagnosed as garden-variety atopic eczema without further investigation, so it is possible that this figure is misleading.