Statistical methods in the surgical literature

BACKGROUND: It is important that clinicians understand statistical methods to incorporate statistics into their own research and to correctly translate published literature into improved patient care. The purpose of this study was to identify frequency and appropriate use of statistical methods in clinical surgical publications during the past 18 years. STUDY DESIGN: The study included randomly selected issues from odd-numbered years of Annals of Surgery (Annals) and Archives of Surgery (Archives) between 1985 and 2003, and issues in 2003 from Journal of the American College of Surgeons (JACS), Journal of Surgical Research (JSR), and Surgery. We identified all statistical procedures reported in each article, examined correctness of methods, and reported trends in publication of statistical methods over time. RESULTS: The proportion of publications incorporating statistics has increased over time. Declining trends were seen in the proportion of articles with no statistics (p < 0.0001). Approximately 35% of articles in 1985 did not use statistics compared with < 10% in 2003. Nonparametric tests increased (p < 0.0001) during the study period. In Archives of Surgery, nonparametric tests increased from 0% in 1985 to 33% in 2003, and in Annals of Surgery, from 12% in 1985 to 49% in 2003. Twenty-seven percent of studies included incorrect selection or reporting of statistical methods. CONCLUSIONS: Overall, the statistical complexity of research in clinical surgery journals is increasing. It is important that clinicians reading this literature have sufficient knowledge of statistical methods to facilitate interpretation of increasingly sophisticated statistical analyses.