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Screening in NZ history challenges & opportunities

Screening in New Zealand – history, challenges and opportunities

Speech notes for plenary presentation to ‘Screening Symposium 2005’
Te Papa, Wellington
9.45am, 3 October 2005

Professor Alistair Woodward
Head, School of Population Health
University of Auckland
Chair, National Screening Advisory Committee

Screening is one of the most powerful tools in the health systems workshop. Examples from the past such as mass x-rays for TB and Pap smears show the potential for screening to improve population health and reduce inequalities. Developments in genetics, diagnostic testing and medical imaging will make screening even more important in the future.

But screening is not straightforward. It is complex, it is expensive, and some aspects of screening are counter-intuitive. (For example, common sense says it must be better to detect disease early, but it is not always so.)

Screening involves trade-offs, such as how to balance a large benefit to a relatively small number of people, with a relatively small amount of harm caused to a large number. Most conditions of interest are uncommon, which means the overwhelming majority of individuals screened are disease-free but they experience discomfort, economic costs, and possibly health risks as a result of investigation.

Screening crosses significant borders in health care. It is population-based, but delivered through clinical services. This means screening programmes involve many disciplines, skill sets, and different world-views on how information is framed, and how we should judge success.

Because screening is not straightforward, it can be difficult to explain. Because there are many valid interests and points of view, it is natural that there is often disagreement about the best course of action.

To explore public expectations, understandings and values concerning screening, I reviewed stories about screening that appeared in the New Zealand print media in a six month period in 2005.

A high level of interest and concern for screening is evident in the large number of stories, and the range of subjects. Four themes emerged. First is the frequent reference to “a fair go” in screening, although just what this means is seldom spelt out. Policy makers commonly define equity in terms of access in proportion to need, where need implies the potential to benefit from health care. But the media references to fairness and justice in screening imply equal provision, regardless of demonstrable capacity to benefit.

Screening stories are mostly built around case studies of individuals, and these tend to be unrepresentative in several important respects. In statistical terms, the media sample over-emphasises younger adults, under-represents Maori, Pacific and Asian ethnic groups, and has a strong bias towards survivors. There is no requirement on the media to be representative – newspapers are not epidemiological journals, and it is a misunderstanding on the part of health researchers to equate what is common with what is newsworthy. But representations in the media undoubtedly affect public perceptions of risk and benefit, and therefore may contribute to differences between the expectations of users and those of the providers of screening services.

Screening, as it appears in the media, frequently lacks a population perspective. To fully understand screening, it is necessary to see both the experience of individuals and the big picture view. Some important features of screening are visible only on a larger scale. For example, a small risk of complications following biopsy may be reassuring for the individual patient, but if a screening programme results in a very large number of people requiring investigation, then the negative impact will be substantial, overall. In a similar vein, we know that the performance of screening tests depends on the context: the benefit-cost ratio varies with disease prevalence, for example. Media representations of screening seldom capture these population-level phenomena.

Who are the authorities on screening? A count of the named “experts” quoted in stories on screening shows a wide spread, clinical specialists being most numerous, followed by diagnostic specialists, service providers (including the Ministry of Health) and consumer advocates. Primary care clinicians appear seldom. The spread is a faithful reflection of the complexity of screening and the variety of perspectives, but this sample suggests equal emphasis is not given in the media to every point of view.

Screening has been, and will remain, a fundamental element in the New Zealand health care system. Screening has been, and in the future will very likely continue to be contentious. A brief review of the public face of screening, as reported in the print media, shows there is a high level of interest in and support for screening. It is plain that expectations of screening vary (such as what is fair provision). Some common misunderstandings of screening recur (confusing population screening with disease diagnosis for example). The personal experiences of screening that are reported are asymmetrical – some experiences are much more likely to be reported than others. The media tends to characterize screening services as a series of personal encounters rather than systems interventions.

Herein lie significant challenges, and opportunities, for all of us working in the field. Providing accurate information is one element of communication about screening; equally important is exploring and understanding values which determine the ways in which information is framed and interpreted, and the trade-offs and balances that must be struck when deciding upon the screening policies of the future.

For further information, contact:
Professor Alistair Woodward
0274 905 954

For media assistance, contact:
Graham Bethune
National Screening Unit
027 471 4255

Bio details – Professor Alistair Woodward
Professor Alistair Woodward is the Chair of the first National Screening Advisory Committee for the Ministry of Health. Professor Woodward graduated in medicine from the University of Adelaide and undertook Public Health Medicine training in the United Kingdom. Professor Woodward was a member of the National Health Committee for six years and is currently on the Board of the Health Research Council. Professor Woodward's main interests are in epidemiology, cancer control and environmental health. For three years he chaired the Evaluation Group for the Australian National Breast Cancer Screening Program. He has also participated in planning and evaluation of screening programmes for colorectal cancer and prostate cancer.


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