Epidemiological Model and Physiological Model Explained
In general, mathematical models and simulations in healthcare can be classified as follows:
- Psychological Model
- Operational Models
- integrated healthcare models
In this article, we discuss epidemiological models and physiological models.
Epidemiological models are used to evaluate disease mortality and morbidity caused by specific risk factors.
For instance, they can be used to evaluate the effects of obesity on cancer incidence and mortality in a population. We then can use these models to understand the effects of a particular intervention (e.g. weight reduction) on the health outcomes of interest (in this case, cancer). They are often used to help policy makers to make decisions.
Veerman et al. (2005) used an epidemiological model to estimate the potential effects of individual nutrition advice via computer-tailored nutrition education on Dutch population (16 million people). They concluded that if the computer-tailored nutrition education reached the entire adult population, it could result in a mortality decrease of 0.4 to 0.7% and save 72 to 115 life-years per 100 000 persons aged 25 years or older. Healthy life expectancy is estimated to increase by 32.7 days for men and 25.3 days for women.
Physiological models are sometimes referred to as "diseased models". They describe the actual physiology of a disease or in some cases of a healthy person.
Often a physiological model focuses on a single organ, e.g. heart model, or a single disease, e.g. diabetes model. The mathematical frameworks underlying these models range from complex partial differential equations to simple state-based Markov models.
Other notable applications of physiological models include:
- pharmacokinetic models, which study the distribution of drug in the body following drug administration
- pharmacodynamic models, which study the biochemical and physiological effects of drugs on the body
These models (mostly based on ordinary differential equations) are widely used in the pharmaceutical industry.
One of the most ambitious attempts to bring together different physiological models is the Physiome Project. The Physiome Project, supported by the the National Simulation Resource at the University of Washington Department of Bioengineering, is more than just a database of all quantitative models relevant to human physiology. First, it collects information at multiple scales, ranging from the smallest scale (i.e. genome, proteome, cell) to the scale of organs . Then, it integrates information, by supplying quantitative descriptions of relationships and interactions within and between different components, together with parameters for different cells , tissues and organs. It is believed such approach will take advantage of international scientific collaboration and change how we think about physiology.
Veerman et al., Using epidemiological models to estimate the health effects of diet behavior change: the example of tailored fruit and vegetable promotion, Public Health Nutrition: 9(4), 415-420
P. J. Hunter, E. J. Crampin, and P. M. F. Nielsen Bioinformatics, multi-scale modeling and the IUPS Physiome Project Brief Bioinform, July 1, 2008; 9(4): 333 – 343.