Enduring support for the case report
Authors: J.E. Mellerio
Journal: British Journal of Dermatology (2019)

Although there has been a significant decline in the number of case reports published in a great many medical journals in recent years, largely because of their negative effect on the increasingly crucial impact factor1 and the acknowledgement that they carry little weight in the hierarchy of evidence-based medicine,2 this should not be equated with a reduction in their popularity nor their ongoing relevance. Indeed, with the launch of many titles solely for case reports and series, the number of peer-review journals publishing these has blossomed to over 160 titles in recent years, many of which offer open access.3 Furthermore, paperless journals profit from fewer challenges from lack of space and also benefit from the ability to undertake online searches for their digital content. For example, in 2017 the Journal of Medical Case Reports had an impact factor of just 0·68 yet had over 1·5 million downloads of its articles,4 attesting to the prevailing popularity of this form of medical writing. So, what is it about the modest case report that has enduring appeal and stimulates the reader's interest? To some extent it may be because of its familiar format; the summation of a history and examination, investigations, management plan and the course of the patient or patients throughout. After all, this reflects day-to-day clinical practice, the interaction and pathways customarily followed in all fields of medicine. The ability to assimilate, condense and relay this material is a key skill learnt as a medical student, carried on and honed throughout one's career; the blueprint remains largely the same, as it does for the case report, too. Presenting cases in a very concise and photographic manner, as with the BJD image gallery case reports, plays out particularly well in dermatology where pattern recognition and visual perception are fundamental competencies. In the same way that the practice of clinical medicine looks likely to maintain its model and process, so will the format of the case report continue to reflect this. However, the comforting familiarity of this structure is in no way a substitute for the fundamental message conveyed in a high-quality case report or series.5 A good case report should formulate a hypothesis and prick one's curiosity.6, 7 It might serve as a reminder of a known finding, offer a more complete description of a rare disorder or its associations, or occasionally present an entirely new entity. Some might uncover a hitherto unrecognized adverse effect of a treatment, or describe the efficacy of a new therapy, highlighting the need for further study in larger cohorts. It may detail new diagnostic techniques or uncover underlying disease mechanisms that point the way to hypotheses concerning future management. So long as medicine develops, these observations and discoveries will keep coming; so long as this prevails, the rationale for the case report as a mechanism for little steps of paradigm shifting will endure, helping us to ‘slowly move from ignorance to insight’.8 What they should not be is novelty for novelty's sake or an account of minor relevance that does not enhance one's learning or have potential for changing practice.9 For this reason, peer review of case reports is essential for making sure that they stand up to scrutiny in delivering a meaningful message and warrant the precious reading time afforded them by the journal's readership. Similarly, adhering to structures for case reporting, such as the CAse REport (CARE) guidelines,5, 10 will ensure that there is as much concordance between reports and series as possible, enabling better amalgamation of information and the potential for systematic reviews of case reports. Case reports that highlight potential new treatments through serendipitous observations can be tremendously enlightening. Consider the impact of minoxidil on the management of alopecia, triggered by a case report of its use in hypertension.11 More recently, the dramatic resolution of a large infantile haemangioma resulting from propranolol administered for cardiomyopathy has led to the most exciting and widely adopted therapeutic innovation in paediatric dermatology for decades.12 The case report or series can serve as the prompt for cohort studies or case meta-analyses, perhaps even clinical trials. While chance discovery can reveal novel treatment options, unravelling of disease mechanisms can likewise prompt therapeutic trials in individual cases or small series, particularly in this era of rapid drug discovery and application. For example, biologics potentially provide rich pickings for repurposing as the field of proteomics uncovers new disease processes. The recent report of secukinumab used for the first time in severe hidradenitis suppurativa based on the role of interleukin-17A in the disease is such an example.13 Similarly, the first report of liraglutide, a glucagon-like peptide-1 agonist with anti-inflammatory and weight reducing properties, used in severe hidradenitis is another.14 Both highlight the need for future case series and clinical trials in larger cohorts. Another area of strength for the case report is in the description of novel adverse drug events that may be lost in translation in large studies where reporting may not have sufficient granularity to highlight unusual or unanticipated issues. Although at the bottom of the evidence pyramid, the humble case report can feed into what makes up the layers above it. As Kidd and Saltman put it, ‘in this era of evidence-based practice, we need practice-based evidence’.15 On a smaller, more local level, a published case report, even with n = 1, can carry some weight when applying for off-licence use of a medication, or for funding applications without a body of supporting clinical trial data. For uncommon or rare diseases, or where the potential financial returns for big pharma are limited, the practicality, funding or impetus for randomized controlled trials is frequently lacking; in this scenario, having at least some rationale derived from case reports and series may be sufficient to put the case for gaining more clinical experience. It is likely that the future impact of the case report will be felt nowhere more than in the field of rare disease and genomic medicine. With around 5000–8000 individual rare diseases and an estimated 3 million of the U.K. population affected by one of these conditions, the collective impact of disease burden is substantial.16 Ambitious initiatives such as the 100 000-genome project will lead to better and faster diagnosis, earlier intervention and the hope for personalized medicine for individuals with genetic disease and cancer. Articles describing disease-causing or disease-modifying genes, specific genotypes and phenotypic correlation, as well as potential pharmacological or gene-related therapies, have increased considerably over the past decade or so. While at one end of the spectrum sit substantial genome-wide association studies in the more common polygenic disorders, at the opposite end, the case report describing an unusual patient can also hold its own. For example, recently Khamaysi et al. identified an activating smoothened gene mutation in segmental basal cell naevus syndrome, with treatment implications for this condition as well as sporadic basal cell carcinomas.17 In another case report, imatinib is used to treat cutaneous vasculopathy in neurofibromatosis.18 Both reports highlight the potential applicability to other individuals with rare genetic disorders. The vast number of genes and related diseases as well as the rarity of these conditions suggest that good-quality, robust clinical trials are fraught with logistical difficulties. However, the role of the case report in making initial steps to highlight potential treatments cannot be underestimated and is unlikely to lose this relevance for many years to come. As the repository of medical knowledge expands at an ever-increasing rate, we need to have robust ways to filter what there is and to retrieve what we need. Google, PubMed and a plethora of other search engines are invaluable, and sites such as UpToDate distil and summarize pertinent and contemporaneous information on many varied topics. However, the influence of individual case reports or small series on such tools is small. The potential for using artificial intelligence in medical practice, across many specialties including dermatology, is becoming increasingly accepted.19 However, given that case reports often communicate unexpected or novel observations, it seems unlikely that the application of artificial intelligence technologies will negate their importance in the short to medium term. With competing pressures on our time and a seemingly exponential growth in the medical knowledge that we need to keep abreast of, can we really be expected to make time for the case report? Arguably, this concise, familiar and entertaining format, easily digested in a short sitting makes it ideal for busy schedules. Couple this with increased availability of material though online access on phones and tablets, options for podcasts or vodcasts while on the go, mean that the case report will surely be here for the foreseeable future. None declared.