Evián  Fernández García

Marcos L. Escobar Añel

Centro Nacional Coordinador de Ensayos Clínicos (CENCEC).

Dirección: 200 y 21. Atabey. Playa. Código Postal: 11 600.

carmen@cencec.sld.cu. Teléfonos: 21-7397, 21-7380, 21-7308. Fax: 33-3391, 33-3509

The clinical trials constitute one of the phases in the development of new therapeutic products. The actual demand of this product by patients, health professionals and productive companies has determined that the clinical trials should be done in an efficient and accelerated way. Due to its economic and ethic repercussion, one important part in the design of a clinical investigation is the determination of the number of patients to be included, because this determinates the cost of the investigation. This requires a correct valuation of the scientific, economic and practical interest to achieve the proposed objectives with the major saving time, humans and economic resource. Another important part is the elaboration of the statistical analysis plan such as its realisation at the moment that the statistical procedure of the information is done. In our work the consequence and the repercussion of an inadequate calculus of the sample size are exposed, such as the low power of the statistical test that is obtained in the execution of interim analyses not forecasted in the investigation design. To resolve this difficulty, our centre is developing a research project about the sample size in the clinical trials joined to the implementation of software that facilitates calculus in a faster way.