[1] Univ Auckland, Fac Med & Hlth Sci, Dept Gen Practice & Primary Hlth Care, Ageing Well, Auckland, New Zealand
[2] Leiden Univ, Med Ctr, Dept Publ Hlth & Primary Care, Leiden, Netherlands
[3] Univ Auckland, Fac Med & Hlth Sci, Hlth Serv Res, Auckland, New Zealand
[4] Univ Auckland, Fac Sci, Dept Stat, Biostat, Auckland, New Zealand
[5] Univ Auckland, Private Bag 92019, Auckland, New Zealand