Reporting bias is prevalent in systematic reviews and meta-analyses related to endoscopic vs. microscopic...

Endoscopic decompression (ED) and microscopic decompression (MD) are newer minimally invasive approaches for surgical treatment of lumbar spinal stenosis (LSS). However, the absence of large, high-quality randomized controlled trials raises concerns for the potential of bias, or spin, in studies evaluating these techniques. This study aims to analyze the prevalence of spin in abstracts of systematic reviews and meta-analyses comparing ED and MD as treatments for LSS.

Studies were identified using the Preferred Reporting Items for Systematic Reviews and Meta Analysis guidelines searching PubMed, Web of Science (WOS), and Scopus. Articles included were: (I) a systematic review with or without a meta-analysis; (II) degenerative etiology; (III) human subjects; (IV) available in English. Abstracts were graded for incidence of the 15 most common types of spin, and full texts were reviewed using AMSTAR 2 classification. General demographics were identified, including study title, author, journal of publication, year of publication, level of evidence (LOE), study design, and funding. Fisher's exact test was used to compare study metrics.

Ten studies were included, all of which contained at least one type of spin. Spin type 12 ("Conclusion claims equivalence or comparable effectiveness for non-statistically significant results with a wide confidence interval") and type 3 (Selective reporting of or overemphasis on efficacy outcomes or analysis favoring the beneficial effect of the experimental intervention) were the most common forms of spin, found in 5/10 (50%) of the included studies. All 10 studies received a confidence rating of "critically low" according to the AMSTAR 2 domain. There were no significant associations between incidence of spin type and year of publication, journal of publication, number of citations, LOE, funding, Clarivate impact factor, or ScopusCiteScore.

Spin is highly prevalent in abstracts of systematic reviews and meta-analyses investigating ED versus MD. All ten manuscripts evaluated received a low quality rating according to the AMSTAR 2 domain.