[Steps to transform a necessity into a validated and useful screening tool for early detection of developmental...

A screening test is an instrument whose primary function is to identify individuals with a probable disease among an apparently healthy population, establishing risk or suspicion of a disease. Caution must be taken when using a screening tool in order to avoid unrealistic measurements, delaying an intervention for those who may benefit from it. Before introducing a screening test into clinical practice, it is necessary to certify the presence of some characteristics making its worth useful. This "certification" process is called validation. The main objective of this paper is to describe the different steps that must be taken, from the identification of a need for early detection through the generation of a validated and reliable screening tool using, as an example, the process for the modified version of the Child Development Evaluation Test (CDE or Prueba EDI) in Mexico.