New Zealand guidelines for the management of dyslipidaemia: Implications for treatment in an urban New Zealand population

Aims. The paper uses coronary heart disease risk factor prevalence data from a defined urban population to assess the potential impact of implementing the New Zealand National Heart Foundation ''Guidelines for detection and management of dyslipidaemia'' on the treatment of dyslipidaemia in New Zealand. Methods. Coronary heart disease risk factor data was collected on an age stratified random sample of Auckland residents aged 35-74 years. The 10 year absolute risk of coronary heart disease was calculated for each participant aged between 35-64 years and management options determined from the National Heart Foundation guidelines. The Framingham equation used in these guidelines was used to extrapolate the 10 year risk of a coronary event in the 65-74 year age group. The proportions of participants potentially requiring treatment with lipid modifying medication were identified and extrapolated to the New Zealand European population. A sensitivity analysis was undertaken to assess the impact of 5% and 10% reductions in total cholesterol following dietary intervention on numbers meeting the drug treatment criteria. Results. The proportion of participants potentially requiring lipid modifying treatment based on the guidelines was considerably higher than estimates of current treatment rates in each age group. The number meeting the treatment criteria increased dramatically with age. By the age of 65-74 years one in five participants met the drug treatment criteria. A 5% and 10% reduction in total cholesterol following dietary intervention reduced the proportion of participants potentially requiring drugs by almost one quarter and one half respectively. Conclusion. The approach taken by the New Zealand National Heart Foundation guidelines appropriately gives highest priority to patients at highest risk of a coronary event. If this high risk approach is extrapolated to older age groups, it will lead to more drug treatment among the elderly. Further evidence from randomised controlled trials on benefits of using cholesterol modifying medication in older age groups is required. Future guidelines need to address specifically criteria for use of Lipid modifying medications in older age groups. Reductions in the numbers meeting drug treatment criteria following 5% and 10% reductions in total cholesterol reinforces the importance of dietary management.