Time trends of smoking cessation: a micro-population computer simulation model

The Micro-population model of Risk-group Dynamics (MRD) approaches smoking behavior at the level of the individual and integrates physiological and social factors to describe the evolution of behavior change in the population. MRD is innovative in several ways: (1) the model describes mathematically the interactions among these behavioral factors; (2) the model accounts for both the variability of these factors among different persons and the universality of basic rules describing these factors in all individuals; and (3) the model can be applied to various types of populations and a wide range of intervention strategies. MRD combines the physiological, psychological and social determinants into a hazard function for relapse to smoking. This hazard function is then organized into a three term expression incorporating: a baseline hazard characteristic to each individual, a decreasing term for the diminishing aspect of the initial hazard and an effect of external interventions. The model gives promising results when applied to the Multiple Risk Factors Intervention Trial (MRFIT) data using the assumptions of a Weibull distribution for the baseline hazard, a negative exponential for the decrease in the initial hazard and a constant intensity for the external intervention.