EFFECT MODELS IN METAANALYSIS

The effect models are defined as the simple or complex relation that t he risk in the treatment group follows when the risk in the control gr oup varies. The standard statistical methods of meta-analysis are base d on simple effect models. The use of these methods could induce inacc urate or erroneous results in more complex situations. in this case, i t is necessary to adopt a more appropriate effect model, such as the l inear effect model. The properties of this kind of model allow the pos sibility that a treatment can be beneficial and harmful at the same ti me, in function of the risk without treatment. From this observation, it is advisable to be careful with the use of simple effect models in meta-analysis which can submerge interesting information in the synthe sis.