[1] Univ Copenhagen, Dept Publ Hlth, Res Unit Gen Practice, Copenhagen, Denmark
[2] Univ Copenhagen, Dept Publ Hlth, Sect Gen Practice, Copenhagen, Denmark
[3] Univ Copenhagen, Dept Publ Hlth, Biostat Sect, Copenhagen, Denmark
[4] Arhus Univ Hosp, Arhus Kommunehosp, Med Dept M, Aarhus, Denmark