A case series is an uncontrolled study of a group of patients with a particular disease or condition who undergo a particular treatment with subsequent outcome(s). Case series are commonly a retrospective review of a string of interesting cases, often with a unifying feature - be that exposure, intervention, treatment or outcome. They are frequent within the medical literature but are also present within social sciences and the humanities. In a 2005 report, Dalziel et al outlined that case series are used in 30 per cent of Health Technology Assessments (HTA) - assessments used in the provision and suitability of care (Dalziel et al, 2005). In the summer of 1999, the use of a case series in the recognition of a new disease was exemplified by the epidemic of West Nile encephalitis in New York City (Lancet editorial, 1999). Historically case series were important in identifying the dangers of Thalidomide for pregnant women and the role of vitamin C in preventing scurvy. More recently a study by Albrecht of case series, published in the Lancet, found that a high proportion went on to have follow-up trials and that they were useful in establishing treatments for rare diseases in which trials would not be feasible (Albrecht et al, 2005). For some specialities, establishing control groups may be difficult, e.g. accident and emergency medicine. In the social sciences, many social psychology studies have been case series, e.g. Yale psychologist Stanley Milgram’s seminal work on obedience to authority figures.
Currently, no standardised reporting criteria developed within a robust methodological framework exist for case series. In the on-going drive to improve the evidence base for clinical practice, a number of tools have been developed to improve the quality of reporting research. For example, publication of CONSORT (Consolidated Reporting Standards of Randomised controlled Trials) has seen the quality of articles in some fields improve significantly (Moher et al, 2001; Plint et al, 2006). A wide variety of reporting guidelines are now available across different research study types, except for case series. Problems in the reporting of case series have been highlighted from recent experience of conducting a systematic review of autologous fat grafting for breast reconstruction. In this study, 25 of the 31 included studies were case series, yet 20 per cent did not mention the age of the participants and 48 per cent did not mention whether the participants had had radiotherapy an important prognostic factor. Readers need complete, clear and transparent information and failure to provide this short-circuits critical appraisal and any assessment of external validity and whether, for instance, a surgeon should change their practice. This project aims to close this gap and help produce a reporting guideline for case series that is methodologically robust, easy to use, and accepted internationally across a broad range of specialities and disciplines.
The final paper has now been accepted for publication and can be found here.
Riaz Agha, Department of Continuing Education and Balliol College, University of Oxford
Professor Dennis Orgill, Harvard Medical School, Harvard University
Contact details for enquiries
Please email the lead investigator, Riaz Agha, for any queries regarding this project.