University of Otago health policy Associate Prof Robin Gauld spent a year in the United States as a Harkness Fellow at Boston University during 2008 and 2009.
His research has been accepted for the American Journal of Medical Quality.
Prof Gauld studied unwarranted clinical variation at five US hospitals, and surveyed a further 304 hospitals.
Unwarranted clinical variations is when clinicians prescribe treatments and medications that cannot be explained by the individual nature of the case.
The research focused on whether unwarranted clinical variation was an issue, what strategies were in place and how successful they were.
Potentially, patients received different care depending on their hospital and individual clinician, Prof Gauld said.
Many factors influenced unwarranted variations, including when and where clinicians trained, whether they had set guidelines to follow and communication systems.
A concern in the US was "defensive medicine", a result of the litigious nature of US medicine, where clinicians tended to overprescribe treatment and medicine in a bid to head off potential legal action from patients.
Compared with the US, where millions missed out on health care, New Zealand had a good system given its budget, with well-trained doctors and nurses.
Prof Gauld could not comment directly on unwarranted variation in New Zealand, but reducing it could have big benefits for a tiny country with a relatively small health budget.
Prof Gauld advocates a "production-line" approach to both primary and secondary care, with hospitals working like "machines" to eliminate variations and anomalies.
If New Zealand's health-care system was to embrace the production-line ethos, it could save money, improve patient care and reduce clinician turnover.
The Southern District Health Board presented exciting opportunities, and he was heartened by some of the work being done to streamline practices and create efficiencies in the new board.
Prof Gauld emphasised that while the production-line approach sounded prescriptive, it allowed for patient-centred care.
Prof Gauld said while the New Zealand model of health care was superior to that in the US, he was concerned the district health board structure, though laudable in spirit in promoting local decision-making, effectively outsourced the government's "dirty work".
Politicians could take the heat out of unpleasant cost-cutting decisions, but take credit for the system's success stories.
Harkness Fellowships were awarded by the Commonwealth Fund, which sought to promote better access to health care in the US, more emphasis on primary care and greater consistency between states, Prof Gauld said.
