When is the evidence too old?

A few weeks ago, when submitting an abstract to a nursing conference, I was suddenly faced with a dilemma about age. Not my own age, but the age of evidence I was using to support my work. One key element of the submission criteria was to provide five research citations to support the abstract, and all citations were to be less than ten years old.  This requirement left me stumped for a while. The research I wanted to cite was more than ten years old, yet it was excellent research within a very small body of work on the topic. Suddenly I struggled to meet the criteria and almost gave up on the submission, thinking my abstract would not tick all of the boxes if I used research now deemed to be ‘out of date’. I suddenly thought about all of the work I had published more than ten years ago – all that hard work past its use-by date.

Way back in the mid 1990s, a colleague and I started to have conversations with Australian nurses about the importance of evidence based practice (EBP) for the future of Australian nursing.  The movement away from the comfort of ‘ritual and routine’ to the uncertainty of EBP was challenging. At the time we described EBP according to the principle that “all interventions should be based on the best currently available scientific evidence” 1. We had embraced the ideas of authors such as Ian Chalmers2 and were keen to educate nurses and nursing students about “practices that had been clearly shown to work and question practices for which no evidence exists and discard those which have been shown to do harm” 1 It was very much about the importance of using the most ‘robust’ and ‘reliable’ evidence that we had available to guide us in clinical decision making, taking into account individual patients at the centre of care. It was also about teaching nurses and nursing students about how to ask the right questions, where to look for answers and how to recognize when you have found the right answer to support individualized patient care.

Definitions of evidence-based practice are quite varied and I have heard nurses talk about using “current best evidence” while others use the “most current evidence”. These are quite different approaches, with the latter statement suggesting that more recent is best. This is sometimes reinforced in nursing education, where students are graded according to the use of recent research, with limitations placed on the age of resources used to support their work. However, I wonder if we are losing something in this translation about the meaning of ‘best evidence’ to support care. When does the published evidence get too old and where do we draw the line and stop reading research from our past?

Personally I have always expected my students to use up to date research when supporting their recommendations for care. However, I have also encouraged them to look back to see where the new research has come from and to acknowledge the foundation it has been built on.  I am always keen to hear about the latest developments in healthcare and work to support the readers of EBN who need and want to know about what is new and important in the health care literature. Keeping up to date with new evidence is critically important for change. But I wonder how we strike a balance between absorbing recent research and taking into account robust research that preceded its publication by more than a decade?

So, let’s think about these ideas for a minute. If we put our blinkers on and ignore important research from the recently ‘outdated’ literature from the 1990s (when I first became interested in doing research), we could miss some important foundational work that still influences practice today. The two references I have used below, both from the 1990s, would not be included in the discussion at all. If we only consider literature that is recent, and value that more highly than if it is robust, then we will be missing important evidence to inform practice. Researchers could start asking the same research questions over and over (I have seen some of this already in nursing literature) and even feel pressured to repeat previous studies all over again to check if the findings still hold true in the contemporary world. Perhaps that is something to watch for in the future.

It is important to keep up to date with current research findings, new innovations in care, recent trends in patient problems, trends in patient outcomes and changes in the social, political and system context of the care we provide. But it is also important to look back as we move forward, thinking about the strength of the evidence as well as its age.


Allison Shorten RN RM PhD

Yale University School of Nursing



  1. Shorten A. & Wallace MC. ‘Evidence-based practice – The future is clear’. Australian Nurses Journal, 1996, Vol. 4, No. 6, pp. 22-24.
  1. Chalmers I. The Cochrane collaboration: Preparing, maintaining, and disseminating systematic reviews of the effects of health care, Annals New York Academy of Science, 1993, Vol. 703, pp. 156-165.

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