[Variations in clinical practice. Current status and challenges for nursing].

The clinical practice can vary in every step of the process. The following article provides an overview of the most important concepts in the study of variations in clinical practice and the status of nursing regarding these variations. The variability can be seen both from a population and an individual point of view. These variations in practice have problems with quality of care and show that the practice is poorly based in research. The uncertainty hypothesis is the most cited as a primary cause of variations and leads to a style of practice by health professionals to use procedures which have ambiguous incomplete evidence. The main actions to address variations should focus on unwarranted variations and should be developed at institutional level. Most variability studies have been performed from the physician perspective and much less has been done from a nursing one. Paradoxically, few studies have described the level of variability in nursing, however, there are more studies on clinical practice guidelines, clinical pathways and protocols that attempt to standardise practice. Variability is therefore a phenomenon that is presumed to exist, but in many cases is unknown.