[1] Finnish Inst Hlth & Welf, POB 30, FI-00271 Helsinki, Finland
[2] Univ Helsinki, Fac Social Sci, POB 54, Helsinki 00014, Finland
[3] Aalto Univ, Dept Comp Sci, POB 15400, FI-00076 Helsinki, Finland
[4] Aalto Univ, Dept Ind Engn & Management, POB 11000, FI-00076 Helsinki, Finland
[5] Queens Univ Belfast, Royal Victoria Hosp, Ctr Publ Hlth, Inst Clin Sci, Belfast BT12 6BA, Antrim, North Ireland