What's in a Name? The Incorrect Use of Case Series as a Study Design Label in Studies Involving Dogs and Cats

Abstract

BackgroundStudy design labels are used to identify relevant literature to address specific clinical and research questions and to aid in evaluating the evidentiary value of research. Evidence from the human healthcare literature indicates that the label “case series” may be used inconsistently and inappropriately.ObjectiveOur primary objective was to determine the proportion of studies in the canine and feline veterinary literature labeled as case series that actually corresponded to descriptive cohort studies, population‐based cohort studies, or other study designs. Our secondary objective was to identify the proportion of case series in which potentially inappropriate inferential statements were made.DesignDescriptive evaluation of published literature.ParticipantsOne‐hundred published studies (from 19 journals) labeled as case series.MethodsStudies were identified by a structured literature search, with random selection of 100 studies from the relevant citations. Two reviewers independently characterized each study, with disagreements resolved by consensus.ResultsOf the 100 studies, 16 were case series. The remaining studies were descriptive cohort studies (35), population‐based cohort studies (36), or other observational or experimental study designs (13). Almost half (48.8%) of the case series or descriptive cohort studies, with no control group and no formal statistical analysis, included inferential statements about the efficacy of treatment or statistical significance of potential risk factors.ConclusionsAuthors, peer‐reviewers, and editors should carefully consider the design elements of a study to accurately identify and label the study design. Doing so will facilitate an understanding of the evidentiary value of the results.

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“…A study was included if the full text could be obtained from any of the University of Nottingham libraries or e-libraries, through University of Nottingham journal subscriptions, during one of three visits to the British Library, or from free online Open Access. In order to determine study design, published definitions were used [20–22]…”

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“…Classification of observational and descriptive studies is currently an area of considerable debate [ 20 , 21 ]. Descriptive studies reporting outcomes from a single intervention were considered to be surgical case series [ 21 , 22 , 23 ].…”

“…Descriptive studies reporting outcomes from a single intervention were considered to be surgical case series [ 21 , 22 , 23 ]. Observational studies that compared the treatment effects of two or more interventions were considered to have features of a cohort study [ 20 , 21 , 22 , 24 ].…”

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