[1] Vrije Univ Amsterdam, Med Ctr, Dept Publ & Occupat Hlth, EMGO Inst Hlth & Care Res,Expertise Ctr Palliat C, NL-1081 BT Amsterdam, Netherlands
[2] Vrije Univ Amsterdam, Med Ctr, Dept Epidemiol & Biostat, EMGO Inst Hlth & Care Res, NL-1081 BT Amsterdam, Netherlands