"Spin" in Observational Studies in Deep Inferior Epigastric Perforator Flap Breast Reconstruction: A Systematic Review.

[UNLABELLED] The deep inferior epigastric artery perforator (DIEP) flap is widely used in autologous breast reconstruction. However, the technique relies heavily on nonrandomized observational research, which has been found to have high risk of bias. "Spin" can be used to inappropriately present study findings to exaggerate benefits or minimize harms. The primary objective was to assess the prevalence of spin in nonrandomized observational studies on DIEP reconstruction. The secondary objectives were to determine the prevalence of each spin category and strategy.

[METHODS] MEDLINE and Embase databases were searched from January 1, 2015, to November 15, 2022. Spin was assessed in abstracts and full-texts of included studies according to criteria proposed by Lazarus et al.

[RESULTS] There were 77 studies included for review. The overall prevalence of spin was 87.0%. Studies used a median of two spin strategies (interquartile range: 1-3). The most common strategies identified were causal language or claims (n = 41/77, 53.2%), inadequate extrapolation to larger population, intervention, or outcome (n = 27/77, 35.1%), inadequate implication for clinical practice (n = 25/77, 32.5%), use of linguistic spin (n = 22/77, 28.6%), and no consideration of the limitations (n = 21/77, 27.3%). There were no significant associations between selected study characteristics and the presence of spin.

[CONCLUSIONS] The prevalence of spin is high in nonrandomized observational studies on DIEP reconstruction. Causal language or claims are the most common strategy. Investigators, reviewers, and readers should familiarize themselves with spin strategies to avoid misinterpretation of research in DIEP reconstruction.