title: Statistical testing against baseline was common in dental research.
abstract: OBJECTIVE
  To assess the presence of within-group comparisons with baseline in a subset of leading dental journals and to explore possible associations with a range of study characteristics including journal and study design.
  
  
  METHODS
  Thirty consecutive issues of five leading dental journals were electronically searched. The conduct and reporting of statistical analysis in respect of comparisons against baseline or otherwise along with the manner of interpretation of the results were assessed. Descriptive statistics were obtained, and chi-square test and Fisher's exact were undertaken to test the association between trial characteristics and overall study interpretation.
  
  
  RESULTS
  A total of 184 studies were included with the highest proportion published in Journal of Endodontics (n = 84, 46%) and most involving a single center (n = 157, 85%). Overall, 43 studies (23%) presented interpretation of their outcomes based solely on comparisons against baseline. Inappropriate use of baseline testing was found to be less likely in interventional studies (P < 0.001).
  
  
  CONCLUSIONS
  Use of comparisons with baseline appears to be common among both observational and interventional research studies in dentistry. Enhanced conduct and reporting of statistical tests are required to ensure that inferences from research studies are appropriate and informative.
authors: Department of Orthodontics, School of Dentistry, University of Athens, 2 Thivon St, 11527 Goudi, Athens, Greece. Electronic address: d.koletsi@gmail.com.
authors: Despina
authors: D
authors: Koletsi
authors: Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, Turner St., London E1 2 AD, UK.
authors: Arun
authors: A
authors: Madahar
authors: Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, Turner St., London E1 2 AD, UK.
authors: Padhraig S
authors: PS
authors: Fleming
authors: Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Freiburgstrasse 7 CH-3010, Bern, Switzerland.
authors: Nikolaos
authors: N
authors: Pandis
mesh_terms: D000818:Animals; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D018865:Dental Research / Q000379:methods* / Q000706:statistics & numerical data*; D004708:Endodontics; D006801:Humans; D016247:Information Storage and Retrieval; D055811:Journal Impact Factor; D011642:Publications / Q000145:classification; D012107:Research Design
keywords: Analysis; Baseline testing; Dental; Reporting; Statistics; Within group comparison