Clinical models are mental or computer representations of physiological and pathological phenomena that are used for predicting patient evolution.

This term is being used in the literature in ways which might appear different from the above definition at the first glance, but in fact they are just the same concept used in some narrower sense.

1. A specific disease is named a `clinical model' as a prototype of a number of similar diseases; for example, pneumococcal pneumonia is called a `clinical model' of most bacterial pneumonias, primarily for didactic purposes: most pneumonias share similar features which are shown for the pneumococcal variety together with peculiarities of each variety.

   This use can also be read using our definition, as follows: an abstract general mental representation of many bacterial pneumonias is built, which is based on the prototype variety. Lacking a better model, this general one is of some predictive usefulness, but can be improved by augmenting it with specifics for nonpneumococcal infections.

2. A disease which is the effect of a simple pathological process is called a `clinical model' of the process. This is like saying `we don't need to make an experimental model of the process in an animal as it happens for these patients to exhibit that process in a pure form and we could study it by investigating them'.

   The purpose of this kind of clinical models is to provide a prototypical description of a pathological process to be used in clinical models of cases that exhibit either a part of that process or include a variety of the process together with other processes.

3. Clinical cases as an experimental model to test some hypothesis are also sometimes called clinical models. The title of this paper says it all: `Asthma stability after oral prednisone: a clinical model for comparing inhaled steroid potency.' (Lux & al, Am J Respir Crit Care Med 2001;164:1138-45).

   Cases with typical, pure pathological processes are used as prototypes of therapeutical interventions. The term `clinical model' also refers to an abstraction of similar cases, in this case under a variety of treatments with some experimental intention, rather than for illustration (as in form 1) or observational study (as in form 2).

4. The term is used as in our definition but in narrower sense, of a predictive model in which the independent variables are clinical features of a case, that is symptoms and clinical signs of a patient---and the dependent variable is of course some measure of outcome, such as survival, response to treatment, remision, etc.
5. The term is used frequently in clinical psychology and in psychiatry, but the purposes of this site and of the definition we use here are restricted to organic diseases and their organic manifestations.