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Research team

Principal Investigator

  • Professor Peter Davis, Christchurch School of Medicine and Health Sciences


  • Dr Sue Crengle [Māori and Pacific Health, Auckland]
  • Dr Peter Crampton [Public Health, Wellington School of Medicine and Health Sciences]
  • Dr Phil Hider [Christchurch School of Medicine and Health Sciences]

Supported by the Health Research Council


The primary aim of the research is to expand knowledge of the nature and frequency of activities occurring in primary care. A critical component of this will be to compare parameters of care across organisational settings. Secondary aims are to investigate changes across time, to validate electronic methods of data collection recently introduced and to establish a method of data collection for the ongoing monitoring of primary care.


Only limited descriptive information on primary care in New Zealand is available. Data from subsidy claims is incomplete and not readily accessible.

Primary care is delivered in various settings and under various contractual arrangements. Distinct incentives apply in each situation and it is likely that practice patterns differ in unintended, as well intended, ways. Variations to traditional general practice include: practice within independent practitioner associations; capitation schemes and budget holding arrangements; not-for-profit community-focused (third sector) organisations including Maori, community and union health providers; accident and medical centres; and primary care delivered within hospital emergency departments.

Some practice organisations have begun to collect more complete data using electronic methods. The validity of this data collection has not been examined.
A similar research project (WaiMedCa) was undertaken in the Waikato between from 1991 and 1992. The resulting data have been widely used by health planners, as one of the few reliable sources of detailed information on general practice in New Zealand. Such data are collected on an on-going basis in the UK, the US and Australia.


A selection of organisations delivering primary care across New Zealand have agreed to support the research. From these, a complete list of individual medical practitioners will be developed and from this a random sample will be drawn. About 50 practitioners from each organisational setting will participate. The selected doctors will be approached and asked to report patient visits information. At each practice data will be collected for each of two one week periods separated by six months.

A brief record will be kept of all patients seen and more detailed information provided on every fourth patient. Data recorded will include: demographic information on the patient; the reason for the visit; diagnoses made; tests ordered; and treatment recommended. Information on the nature of the practice setting will also be gathered during the preparation phase.
For each of the data elements a distribution will be calculated and these will be compared across organisational types. Analytical steps appropriate to the clustered observations will be used and significant differences identified.


New organisational arrangements have been initiated by the HFA, by private providers of health care and by Maori and other community groups. It is essential that the parameters of primary care be monitored and compared to identify whether the intended benefits have been achieved and whether unintended effects have occurred. It is also desirable that new collection methods for routine data be validated and that an ongoing monitoring system be put in place.

Key questions include the: effect of budget holding on test use and drug prescription; effect of capitation payment on visit numbers or type; level of pathology and socioeconomic deprivation among patients seen at Maori and third sector clinics; proportion of new patients at A&M centres; degree of overlap between emergency department and general practice.


Ministry of Health website reports

Hider P, Lay-Yee R, Davis P. The Work of Doctors in Accident and Medical Clinics: The National Primary Medical Care Survey (NatMedCa): 2001/02. Report 5. Wellington: Ministry of Health. 2005.

Hider P, Lay-Yee R, Davis P. A Comparison of Primary Health Care Provided by Rural and Non-Rural General Practices: The National Primary Medical Care Survey (NatMedCa): 2001/02 Report 4. Wellington: Ministry of Health. 2004

Davis P, Gribben B, Scott A, Lay-Yee R. Do physician practice styles persist over time? Continuities in patterns of clinical decision-making among general practitioners Journal of Health Services Research and Policy 5(4): 1-8, 2000.

Davis P, Gribben B, Scott A, Lay-Yee R. The "supply hypothesis" and medical practice variation in primary care: testing economic and clinical models of inter-practitioner variation. Social Science and Medicine 50: 407-18, 2000.

Davis P, Lightfoot R, Finn E, Lay-Yee R, Gribben B, McAvoy B. Practice nurses in the Waikato, 1991-1992: What was their patient mix and pattern of care? New Zealand Family Physician 26: 50-54, 1999.

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