1. Department of Preventive and Social Medicine, University of Otago Dunedin School of Medicine, Dunedin, New Zealand.
2. Te Omanga Hospice, Lower Hutt, New Zealand.
3. Biostatistics Group, University of Otago, Wellington, New Zealand.
4. Department of General Practice and Primary Care, The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand.
5. Tu Kotahi Māori Asthma and Research Trust, Lower Hutt, New Zealand.
6. Wellington Regional Hospital, Wellington, New Zealand.