Inclusion and exclusion criteria applied to identify the study population. This figure displays how inclusion and exclusion criteria were applied to identify the study population. Prior to obtaining data from PHIS, 11 hospitals that do not submit gestational age information were excluded. From the initial study population of infants 30 to 34 weeks gestation admitted in the first 48 hours of life, exclusion criteria were applied sequentially.
Kaplan et al. BMC Health Services Research 2011 11:22 doi:10.1186/1472-6963-11-22