title: How confidence intervals become confusion intervals.
abstract: BACKGROUND
  Controversies are common in medicine. Some arise when the conclusions of research publications directly contradict each other, creating uncertainty for frontline clinicians.
  
  
  CONCLUSIONS
  In this paper, we review how researchers can look at very similar data yet have completely different conclusions based purely on an over-reliance of statistical significance and an unclear understanding of confidence intervals. The dogmatic adherence to statistical significant thresholds can lead authors to write dichotomized absolute conclusions while ignoring the broader interpretations of very consistent findings. We describe three examples of controversy around the potential benefit of a medication, a comparison between new medications, and a medication with a potential harm. The examples include the highest levels of evidence, both meta-analyses and randomized controlled trials. We will show how in each case the confidence intervals and point estimates were very similar. The only identifiable differences to account for the contrasting conclusions arise from the serendipitous finding of confidence intervals that either marginally cross or just fail to cross the line of statistical significance.
  
  
  CONCLUSIONS
  These opposing conclusions are false disagreements that create unnecessary clinical uncertainty. We provide helpful recommendations in approaching conflicting conclusions when they are associated with remarkably similar results.
authors.forename: James
authors.initials: J
authors.lastname: McCormack
authors.forename: Ben
authors.initials: B
authors.lastname: Vandermeer
authors.affiliation: Evidence-Based Medicine, Department of Family Medicine, University of Alberta, Room 1706 College Plaza, 8215 - 112 Street NW, Edmonton AB, Canada. michael.allan@ualberta.ca.
authors.forename: G Michael
authors.initials: GM
authors.lastname: Allan
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use; D001552:Benzazepines / Q000009:adverse effects / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000209:etiology / Q000401:mortality; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D019317:Evidence-Based Medicine; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use; D011810:Quinoxalines / Q000009:adverse effects / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D016896:Treatment Outcome; D035501:Uncertainty; D000068580:Varenicline
chemical_list: D000925:Anticoagulants; D001552:Benzazepines; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011810:Quinoxalines; D000068580:Varenicline