Evidence-based medicine in retina

What is evidence-based medicine, or EBM? EBM is when we apply the shared knowledge of the medical community to a specific patient and that patient’s specific situation. That shared knowledge is “located” in the medical literature–the collection of scholarly publications that define the scientific knowledge within a field.

Within ophthalmology, there are major journals that have been published monthly for many years. The four major journals that pertain to retinal diseases are Ophthalmology, the American Journal of Ophthalmology, Archives of Ophthalmology, and Retina. There are other journals as well. The “Catalog” of all the articles in these journals is kept by the National Library of Medicine, which is physically located on the campus of the National Institutes of Health (where Dr. Dahr trained in Washington, D.C.) but is located on the Internet at www.Pubmed.com.

Over the years, the National Insitutes of Health has conducted major clinical trials that have defined how we approach many retinal diseases. The results of these large clinical trials (for example, the AREDS or Age Related Eye Disease study) represent the “best” evidence-based medicine because these trials enrolled hundreds or thousands of patients and were conducted in a scientific manner. These clinical trials results have been published over the years in the major journals (see links below).

Large scale clinical trials run by the NIH constitute the “best evidence” but we do not always have a large clinical trial for every disease. So in the medical literature we have “case series” publications that are published. There may be a disease for which there has not been a large clinical trial, either because the disease does not affect enough people to justify the tens of millions of dollars a large trial costs, or because the results of a large trial have not yet come out. A case series is a collection of five, ten, twenty, maybe even a hundred or two hundred patients, where the experiences of those patients has been analyzed, often in a retrospective or “looking back” fashion. Case series provide us important information and often influence medical practice in a significant way. Case series also often “pave the way” for a large scale, prospective or “looking forward” clinical trial.

Lastly we may even have “Case reports” where the scientific article simply discusses one or two patients. This level of evidence is considered the “weakest” but, for rare diseases or new treatments, it’s often all we have!

Even we have high level clinical trials evidence, that clinical trial may not apply in an exact fashion to your–the patient–situation in an exact fashion. Your eyes may be a little different than the eyes that were studied in the clinical trial.

This scenario is where the “art” of medicine comes in–we as physicians take the results of clinical trials, combine that with our experience and with a patient’s individual characteristics and preferences, and make a decision together–the physician and the patient.

One increasing problematic issue in the medical literature: the influence of drug companies on scholarly (or what are supposed to be scholarly) publications is growing. Drug companies do tremendous amounts of excellent research, produce good medicines, and often run their own clinical trials. However, there is a “line” and sometimes this line is crossed as drug companies seek to promote their drugs. Recent articles in the New York Times and in JAMA detail how drug companies seek to influence the medical literature in ways that are often not disclosed, to patients or to doctors. Dr. Dahr does not have any financial relationships with any companies (see Disclosure).

We are lucky in the retina community in that most of the large clinical trials that have established how we practice Retina were funded by the National Institutes of Health. See the links below for evidence based medicine as applied to major retinal diseases.