[1] Univ Michigan, Med Sch, Internal Med & Pediat, Ann Arbor, MI 48109 USA
[2] Texas Childrens Hosp, Dept Pediat, Houston, TX 77030 USA
[3] Baylor Coll Med, Houston, TX 77030 USA
[4] Univ Calif San Diego, Sch Med, Family Med & Publ Hlth, La Jolla, CA 92093 USA
[5] RCSI Univ Med & Hlth Sci, Dublin, Ireland
[6] Univ Texas Hlth Sci Ctr Houston, McGovern Med Sch, Houston, TX 77030 USA
[7] Univ Leicester, Sch Med, Leicester, Leics, England
[8] Blackpool Victoria Hosp, Blackpool, England
[9] Univ Cent Lancashire, Sch Med, Preston, Lancs, England