Case history: more than a beauty case!

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Case histories form a substantial element of the medical literature. However, due to their inherent anecdotal and observational nature, the description of an individual patient report is hardly considered to contribute to evidence-based medicine. For these reasons, some journals even exclude case histories from publication. Is this a good policy? In my opinion, on the contrary! Case histories can be the true background for systematic or hypothesis-based research. The accurate observation and description of a single patient case may form the basis for further exploration of the observed phenomenon, thus opening new fields of interest. The role of case histories is therefore to expand our knowledge based on incidental experiences. The first clues about tobacco smoking and lung cancer came from surgical patient series in the 1920s and 1930s; formal case-control and cohort studies came only decades later.1 Needless to say, case histories should provide novel information such as progress in diagnostic techniques or advances in treatment modalities. Consequently, interesting case histories should definitely be published with the aim of spreading the information among scientists who may have had similar experiences. When consistent patterns are recognised in multiple cases, these patterns may result in useful integration of information and in the definition of a new hypothesis, a new disease, and applications of new techniques and treatments. For instance, recognition of side effects of drugs is usually based on the identification of multiple identical observations by individual physicians. Unexpected adverse effects are by definition due to unknown mechanisms, and many established adverse effects still escape elucidation after years; further accumulation of anecdotal reports can provide sufficient evidence.2 A ten-year score of 22 drugs that were withdrawn from the market showed that 18 drugs were prompted by case reports and only four by a controlled study; for at least 13 drugs the case reports proved sufficient reason for withdrawal.3 As a consequence, published case reports remain a valid and efficient source for signal generation and are of great value for drug safety.4 Eventually, the summation of sufficient identical cases might result in designing new multicentre clinical trials with potential implication for changing existing guidelines or even the creation of new guidelines. Along those lines the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement has been launched which is a network of methodologists, researchers and journal editors to develop recommendations for reporting observational research.5 Randomised trials cannot answer all the important questions about a given intervention. Observational studies are more suitable for detecting rare or late adverse effects of treatments, and are more likely to provide an indication of what is achieved in daily medical practice. The aims and use of the STROBE statement are to create a checklist of items that should be addressed in articles reporting on the three main study designs of analytical epidemiology: cohort, casecontrol, and cross-sectional studies. The STROBE checklist should be used in conjunction with the explanatory article, which is available freely on the websites of PLoS Medicine (www.​plosmedicine.​org), Annals of Internal Medicine (www.​annals.​org), and Epidemiology (www.​epidem.​com). …