Modelling future mortality in Ontario: Extension of the PREVENT model and development of an Ontario database.

Abstract

PREVENT is a user-friendly, interactive computer program developed in the Netherlands which integrates the effects of demographic structure, risk factor prevalence, relative risks and mortality rates to estimate the impact of changes in risk factor prevalence on mortality. A new database for PREVENT has been developed with the following Ontario data: population structure, all-cause and disease-specific mortality, life expectancy, and birth projections. The current prevalence of smoking, obesity, alcohol and seat belt use is estimated from the Ontario Health Survey; the prevalence of hypertension and hypercholesterolemia from provincial heart health surveys. Future changes in risk factor prevalences for the simulation period are extrapolated from past trends. Sensitivity testing shows that the mortality varies directly with both the prevalence and relative risks. The shape of the mortality prevention curve is affected by two factors. In the first twenty years the latency and lag times and the spread in implementation of the intervention dictate the pattern. In later years mortality is affected by the changing demographic structure, age-specific mortality rates and future trends in risk factor prevalence that are in the model. Historical testing of the risk factor smoking, using a 1966 Ontario database, shows good agreement between PREVENT estimates and observed total mortality. The agreement between predicted and observed mortality is not as close for lung cancer, IHD and COLD.