To the Editor,
We read with great interest the article by Liawrungrueang et al. [1], “Endoscopic spine surgery for obesity-related surgical challenges: a systematic review and meta-analysis of current evidence.” The author addressed an important and timely topic; however, we wish to raise a methodological concern regarding the definition of obesity applied in the included studies. In the eligibility criteria, the review restricted inclusion to studies enrolling patients with a body mass index (BMI) ≥30 kg/m2. This threshold follows the World Health Organization (WHO) global standard, where obesity is defined as BMI ≥30 kg/m2 and overweight as BMI ≥25 kg/m2 [2]. However, closer examination of the included literature reveals that not all primary studies adhered to this definition. Specifically, Wu et al. [3] classified obesity as BMI >28 kg/m2, while Yao et al. [4] used BMI >25 kg/m2 as the obesity threshold. These criteria reflect alternative population-specific definitions, particularly those used in Asian cohorts, where metabolic and cardiovascular risks are elevated at comparatively lower BMI values. The WHO Expert Consultation [5] recommended lower BMI cutoffs for Asian populations: overweight defined as BMI ≥23 kg/m2 and obesity as BMI ≥25 kg/m2. Likewise, the Japan Society for the Study of Obesity defines obesity as BMI ≥25 kg/m2 [6]. This discrepancy in operational definitions of obesity is not trivial. Meta-analytic conclusions may be influenced by heterogeneity in exposure classification, potentially conflating overweight and obese categories across populations. For spine surgery research, where body habitus significantly impacts perioperative risk, surgical difficulty, and recovery, clarity in the applied obesity definition is essential to ensure accurate pooling of data and valid interpretation of results. We commend the author for this valuable contribution and respectfully suggest that future systematic reviews in this domain explicitly address regional variations in obesity criteria. Doing so will enhance the methodological rigor and global applicability of conclusions regarding endoscopic spine surgery in patients with elevated BMI.
Footnotes
Conflict of Interest
No potential conflict of interest relevant to this article was reported.
Author Contributions
All the work for the preparation of this letter was done by all authors.
References
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