PURPOSE: To investigate the prevalence of underpowered randomized controlled trials (RCTs) presented at American Society of Clinical Oncology (ASCO) annual meetings. METHODS: We surveyed all two-arm phase III RCTs presented at ASCO annual meetings from 1995 to 2003 for which negative results were obtained. Post hoc calculations were performed using a power of 80% and an alpha level of .05 (two sided) to determine sample sizes required to detect small, medium, and large effect sizes. For studies reporting a proportion or time-to-event as primary end point, effect size was expressed as an odds ratio (OR) or hazard ratio (HR), respectively, with a small effect size defined as OR/HR >or= 1.3, medium effect size defined as OR/HR >or= 1.5, and large effect size defined as OR/HR >or= 2.0. Logistic regression was used to identify factors associated with lack of statistical power. RESULTS: Of 423 negative RCTs for which post hoc sample size calculations could be performed, 45 (10.6%), 138 (32.6%), and 233 (55.1%) had adequate sample size to detect small, medium, and large effect sizes, respectively. Only 35 negative RCTs (7.1%) reported a reason for inadequate sample size. In a multivariable model, studies that were presented at oral sessions (P = .0038), multicenter studies supported by a cooperative group (P < .0001), and studies with time to event as primary outcome (P < .0001) were more likely to have adequate sample size. CONCLUSION: More than half of negative RCTs presented at ASCO annual meetings do not have an adequate sample to detect a medium-size treatment effect.
PURPOSE: To investigate the prevalence of underpowered randomized controlled trials (RCTs) presented at American Society of Clinical Oncology (ASCO) annual meetings. METHODS: We surveyed all two-arm phase III RCTs presented at ASCO annual meetings from 1995 to 2003 for which negative results were obtained. Post hoc calculations were performed using a power of 80% and an alpha level of .05 (two sided) to determine sample sizes required to detect small, medium, and large effect sizes. For studies reporting a proportion or time-to-event as primary end point, effect size was expressed as an odds ratio (OR) or hazard ratio (HR), respectively, with a small effect size defined as OR/HR >or= 1.3, medium effect size defined as OR/HR >or= 1.5, and large effect size defined as OR/HR >or= 2.0. Logistic regression was used to identify factors associated with lack of statistical power. RESULTS: Of 423 negative RCTs for which post hoc sample size calculations could be performed, 45 (10.6%), 138 (32.6%), and 233 (55.1%) had adequate sample size to detect small, medium, and large effect sizes, respectively. Only 35 negative RCTs (7.1%) reported a reason for inadequate sample size. In a multivariable model, studies that were presented at oral sessions (P = .0038), multicenter studies supported by a cooperative group (P < .0001), and studies with time to event as primary outcome (P < .0001) were more likely to have adequate sample size. CONCLUSION: More than half of negative RCTs presented at ASCO annual meetings do not have an adequate sample to detect a medium-size treatment effect.
Authors: Kanwal Pratap Singh Raghav; Sminil Mahajan; James C Yao; Brian P Hobbs; Donald A Berry; Rebecca D Pentz; Alda Tam; Waun K Hong; Lee M Ellis; James Abbruzzese; Michael J Overman Journal: J Clin Oncol Date: 2015-08-24 Impact factor: 44.544
Authors: Bryan R Garner; Susan H Godley; Michael L Dennis; Brooke D Hunter; Christin M L Bair; Mark D Godley Journal: Arch Pediatr Adolesc Med Date: 2012-10
Authors: Baruch A Brody; Carol M Ashton; Dandan Liu; Youxin Xiong; Xuan Yao; Nelda P Wray Journal: J Am Coll Surg Date: 2012-11-22 Impact factor: 6.113
Authors: Heather Thompson-Brenner; Debra L Franko; Douglas R Thompson; Carlos M Grilo; Christina L Boisseau; James P Roehrig; Lauren K Richards; Susan W Bryson; Cynthia M Bulik; Scott J Crow; Michael J Devlin; Amy A Gorin; Jean L Kristeller; Robin Masheb; James E Mitchell; Carol B Peterson; Debra L Safer; Ruth H Striegel; Denise E Wilfley; G Terence Wilson Journal: J Consult Clin Psychol Date: 2013-05-06