[1] Karolinska Inst, Div Clin Epidemiol, Dept Med Solna, Stockholm, Sweden
[2] Karolinska Univ Hosp, Pediat Oncol Unit, Stockholm, Sweden
[3] Karolinska Inst, Karolinska Univ Hosp, Div Rheumatol, Dept Med Solna, Solna, Sweden
[4] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden