[1] Univ Texas, Sch Nursing, Houston, TX USA
[2] Univ Texas, Sch Publ Hlth, Houston, TX USA
[3] Case Western Reserve Univ, Frances Payne Bolton Sch Nursing, Cleveland, OH 44106 USA
[4] Childrens Hosp Philadelphia, Div Biostat & Epidemiol, Philadelphia, PA 19104 USA