title: Statistical Use in Clinical Studies: Is There Evidence of a Methodological Shift?
abstract: BACKGROUND
  Several studies indicate that the statistical education model and level in medical training fails to meet the demands of clinicians, especially when they want to understand published clinical research. We investigated how study designs and statistical methods in clinical studies have changed in the last twenty years, and we identified the current trends in study designs and statistical methods in clinical studies.
  
  
  METHODS
  We reviewed 838 eligible clinical study articles that were published in 1990, 2000, and 2010 in four journals New England Journal of Medicine, Lancet, Journal of the American Medical Association and Nature Medicine. The study types, study designs, sample designs, data quality controls, statistical methods and statistical software were examined.
  
  
  RESULTS
  Substantial changes occurred in the past twenty years. The majority of the studies focused on drug trials (61.6%, n = 516). In 1990, 2000, and 2010, there was an incremental increase in RCT studies (74.4%, 82.8%, and 84.0%, respectively, p = 0.013). Over time, there was increased attention on the details of selecting a sample and controlling bias, and there was a higher frequency of utilizing complex statistical methods. In 2010, the most common statistical methods were confidence interval for superiority and non-inferiority comparison (41.6%), survival analysis (28.5%), correction analysis for covariates (18.8%) and Logistic regression (15.3%).
  
  
  CONCLUSIONS
  These findings indicate that statistical measures in clinical studies are continuously developing and that the credibility of clinical study results is increasing. These findings provide information for future changes in statistical training in medical education.
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Dali
authors.initials: D
authors.lastname: Yi
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Dihui
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Gaoming
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Xiao
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Yanqi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Hongru
authors.initials: H
authors.lastname: Chen
authors.affiliation: University of Washington, School of Arts and Sciences, Department of Biological Sciences, Seattle, Washington, United States of America; University of Washington, School of Arts and Sciences, Department of Asian Language and Literature, Seattle, Washington, United States of America.
authors.forename: Julia Christine
authors.initials: JC
authors.lastname: Pettigrew
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Yi
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Health Statistics, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Yazhou
authors.initials: Y
authors.lastname: Wu
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design; D012984:Software