Absence of a Positive Outcome Bias in Randomized Controlled Trials of Minimally Invasive Surgical Techniques.

To determine whether a positive primary outcome in randomized controlled trials of minimally invasive surgical techniques predicted publication in higher impact factor journals.

A systematic review of EMBASE (OvidSP®), MEDLINE (OvidSP®), and Cochrane (Wiley®) databases from inception to December 22, 2017 was performed to identify all randomized controlled trials comparing minimally invasive and classical surgical techniques. Our primary study outcome was journal "corrected impact factor", accounting for journal impact factor inflation over more recent publication years. Sensitivity analyses with impact factor operationalized in five additional ways was performed. Univariable and multivariable gamma regression analyses were used to evaluate the association of a positive primary outcome and journal "corrected impact factor".

410 studies were identified. On multivariable gamma regression analysis, a positive primary outcome was not associated with a higher likelihood of publication in a higher impact factor journal (coefficient 1.05, 95% Confidence Interval 0.82-1.35, p= 0.66), with similar negative results consistently demonstrated in all sensitivity analyses performed.

In a systematic review of randomized controlled trials of minimally invasive surgical approaches over the last 20 years, we failed to find evidence that the minimally invasive surgical literature is subject to a positive outcome bias.

Journal of clinical epidemiology. 2020 Dec 03 [Epub ahead of print]

Rashid K Sayyid, Soum D Lokeshwar, David Tella, Caitlin E Jones, Zachary Klaassen, Christopher J D Wallis

Section of Urology, Department of Surgery, Medical College of Georgia-Augusta University, Augusta, GA., Department of Urology, Yale New Haven Hospital, New Haven, CT., Department of Urology, University of Virginia, Charlottesville, VA., Department of Surgery, Medical College of Georgia-Augusta University, Augusta, GA., Section of Urology, Department of Surgery, Medical College of Georgia-Augusta University, Augusta, GA; Georgia Cancer Center, Augusta, GA., Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, TN.