Emergence of 'retropro' studies in the surgical literature.
BACKGROUND
The surgical published work now contains several studies that involve retrospective evaluations of prospectively collected data. These types of studies - that are referred to as 'RetroPro' studies - have the potential to be a valuable source of information about the care of surgical patients. The aim of this study was to evaluate the role of RetroPro studies in the surgical published work.


METHODS
Original articles from 21 surgical journals were selected for study. Rejected from study were case reports, short communications, editorials, and surgical narratives (history, opinions and orations). Each original article was evaluated to determine the source of the study, the topic under evaluation, the sample size, the study design and the use of statistics.


RESULTS
Retrospective studies accounted for 34% of the 1386 original articles. The other main components were single-group prospective studies (20%), non-clinical experimental studies (13%), RetroPro studies (10%), review articles (9%) and clinical trials (5%). Almost one-third of the RetroPro studies evaluated more than 1000 patients and 58% of them included some form of multivariable regression or an analysis of survival; that is, they attempted to model the outcome of surgical patients.


CONCLUSIONS
RetroPro studies are now an important source of information about the outcome of surgical patients. They should be recognized as a specific form of clinical investigation.
Hall
John C
JC
University Department of Surgery, University of Western Australia, Royal Perth Hospital, Perth, Western Australia, Australia. jchall@cyllene.uwa.edu.au
Hall
Jane L
JL
D013502:General Surgery; D006801:Humans; D011446:Prospective Studies; D012106:Research; D012189:Retrospective Studies