[1] Erasmus Univ, Med Ctr Rotterdam, NL-3000 DR Rotterdam, Netherlands
[2] Emma Childrens Hosp AMC, Amsterdam, Netherlands
[3] Sophia Childrens Univ Hosp, Erasmus MC, Rotterdam, Netherlands
[4] Univ Med Ctr Utrecht, Van Creveldklin & Hematol, Utrecht, Netherlands
[5] Leiden Univ, Med Ctr, Dept Clin Epidemiol, NL-2300 RA Leiden, Netherlands