The cost-effectiveness of mammography screening: evidence from a microsimulation model for New Zealand

Mammography screening currently represents the only means by which the mortality rate from breast cancer can be modified substantially. A national mammography screening programme is being considered for New Zealand, and pilot programmes were established in two regions (Otago/Southland and Waikato) in 1991 to determine the potential costs and benefits of mammography for New Zealand women. The aim of this paper is to explore the cost-effectiveness of mammography screening in New Zealand relative to no screening, and to examine the marginal change in costs and benefits of altering programme characteristics such as the age of women invited and screening frequency. Cost-effectiveness is measured by the net cost (the costs of screening minus the treatment savings averted by the early detection of cancers) per year of life gained, from the perspective of the public health care sector. A microsimulation computer model, MICROLIFE, was developed to facilitate the estimation of mortality reduction and cost-effectiveness. The results show that, while mammography screening does not 'save money' overall, the cost per year of life saved for a range of policies compares favourably with other New Zealand health services, and is comparable to the results from economic evaluations of mammography screening overseas. Of those regimes considered, screening women 50-64 years of age at 3-yearly intervals appears to be most cost-effective.