Evaluation of Spin in Systematic Reviews and Meta-Analyses of Minimally Invasive Surgical Techniques and Standard Microdiscectomies for Treating Lumbar Disc Herniation.

Study Design: Systematic review.

Objectives: Spin in scientific literature is defined as bias that overstates efficacy and/or underestimates harms of procedures undergoing review. While lumbar microdiscectomies (MD) are considered the gold standard for treating lumbar disc herniations (LDH), outcomes of novel procedures are being weighed against open MD. This study identifies the quantity and type of spin in systematic reviews and meta-analyses of LDH interventions.

Methods: A search was conducted on the PubMed, Scopus, and SPORTDiscus databases for systematic reviews and meta-analyses evaluating the outcomes of MD against other LDH interventions. Each included study's abstract was assessed for the presence of the 15 most common types of spin, with full texts reviewed during cases of disagreement or for clarification. Full texts were used in the assessment of study quality per AMSTAR 2.

Results: All 34 included studies were observed to have at least 1 form of spin, in either the abstract or full text. The most common type of spin identified was type 5 ("The conclusion claims the beneficial effect of the experimental treatment despite a high risk of bias in primary studies"), which was observed in ten studies (10/34, 29.4%). There was a statistically significant association between studies not registered with PROSPERO and the failure to satisfy AMSTAR type 2 ( < .0001).

Conclusion: Misleading reporting is the most common category of spin in literature related to LDH. Spin overwhelmingly tends to go in the positive direction, with results inappropriately favoring the efficacy or safety of an experimental intervention.