[1] Univ Otago, Dept Publ Hlth, 23a Mein St, Wellington, New Zealand
[2] Univ Otago, Fac Dent, Sir John Walsh Res Inst, POB 56, Dunedin, New Zealand
[3] Univ Auckland, Fac Med & Hlth Sci, Sch Populat Hlth, Private Bag 92019, Auckland 1142, New Zealand
[4] Univ Auckland, Fac Med & Hlth Sci, Sch Nursing, Private Bag 92019, Auckland 1142, New Zealand
[5] CBG Hlth Res Ltd, POB 45173, Auckland 0651, New Zealand