[1] Univ Auckland, Dept Gen Practice & Primary Hlth Care, Sch Populat Hlth, Auckland, New Zealand
[2] Univ Auckland, Goodfellow Unit, Dept Gen Practice & Primary Hlth Care, Sch Populat Hlth, Auckland, New Zealand
[3] Univ Auckland, Sch Nursing, Auckland, New Zealand
[4] Univ Otago, Dept Primary Hlth Care & Gen Practice, Wellington Sch Med & Hlth Sci, Wellington, New Zealand