[1] Univ Oxford, Nuffield Dept Primary Care Hlth Sci, Oxford, England
[2] Univ Oxford, Nuffield Dept Primary Care Hlth Sci, Primary Care, Oxford, England
[3] Univ Oxford, Nuffield Dept Primary Care Hlth Sci, Med Stat, Oxford, England
[4] Aarhus Univ, Res Unit Gen Practice, Aarhus, Denmark
[5] Aarhus Univ, Res Unit Gen Practice, Primary Care, Aarhus, Denmark
[6] Lund Univ, Dept Clin Sci, Family Med, Vaxjo, Sweden