From the point of view of the knowledge that the doctor and the patient they have about the medication that is receiving the patient distinguish the open studies and the blind studies. In the open studies as much the investigator as the patient knows the treatment that receives the patient. Usually they are opened to the studies of prolonged acceptability and tolerance, the studies made in rare or incurables diseases, the studies badly designed and the farmacocinéticas studies. Blind person means ignorance of the identity of the treatment that is received. The blindness is used to eliminate all those subjective factors, as much on the part of the investigator as of the patient, that can bring confusion at the time of interpreting the results of a treatment in study. The blind studies are classified as well in: , 1) Simple blind person, the doctor knows the treatment that receives the patient but the patient does not know it 2) Double blind person neither the investigator nor the patient know the treatment that receives the patient , 3) Triple blind person neither the patient, nor the investigator nor the patrocinante know the assigned treatment the patients In order to establish causality, that is to say, to be able to affirm that a drug produces a certain effect or is superior to another drug, it is necessary to carry out controlled, randomized and blind studies. This type of design as much provides protection against the slant in the allocation on the part of the investigator and the slant in the evaluation of results by the investigator as by the patient. According to the number of measurements that are made of the variable in study the design can be cross-sectional or longitudinal. In the cross-sectional studies the variables in study are moderate a single time, that is to say, that register diverse characteristics of the population in study in a while determined, as if it was a photography of that population. Soon it is examined if some association between the observed characteristics exists. For example, in a certain population data can be gathered on weight, height, numbers of cholesterol and habit to smoke. Through this design it is possible to be determined if there is association between the different variables, but as the temporary sequence is not known the events, cause cannot be established/effect that is causality. In general, the cross-sectional designs are used for studies of biological processes that are carried out within the laboratories, for diagnosis and stratification (normal ranks), for description of diseases and studies of dose (phase I and 11). In the longitudinal design the evolution in the time of the variables in study is evaluated. Most of the studies in which there is an external intervention and are wanted to establish causality are longitudinal. Although frequently a cross-sectional design is more expeditious, the longitudinal design offers better information generally.Thank you for contributing your translation suggestion to Google Translate.
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Thursday, August 9th, 2007 at 7:06 am
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