To the Editor:
In a recent study, Nouri et al. [1] have reported the demographics, presentation, and symptoms of patients with Klippel Feil Syndrome (KFS), and the authors showed that associated comorbidities including Sprengel deformity may be more common in KFS patients with multilevel cervical fusions. We highly appreciate their work on this important topic. However, we found a flaw in the statistical analysis that calls the results into question.
According to the article, the missing ribs rate between the single-level fusion group and multiple-level fusion group was analyzed by the Chi-squared test, and the P value was 0.046. However, from Table 4 of the article, we found that there were more than 20% of cells with an expected value of less than 5 for the “missing ribs rate.” In this case, we should use Fisher’ s exact test instead of Chi-square test [2]. We calculated using Fisher’ s exact test, and the P value was 0.054, which means the missing ribs rate between the two groups was not statistically significant. Thus, we suggest the authors check and analyze the data again in order to present the appropriate conclusion.
References
Nouri A, Patel K, Evans H et al (2019) Demographics, presentation and symptoms of patients with Klippel-Feil syndrome: analysis of a global patient-reported registry. Eur Spine J 28(10):2257–2265
Armitage P, Berry G, Matthews JN (2002) Statistical methods in medical research, 4th edn. Blackwell Publishing, Malden, pp 134–137
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Hu, B., Zhou, H. & Zou, X. Letter to the editor concerning “Demographics, presentation and symptoms of patients with Klippel-Feil syndrome: analysis of a global patient-reported registry” by Nouri et al. [Eur Spine J; (2019) 28(10): 2257–2265]. Eur Spine J 29, 384 (2020). https://doi.org/10.1007/s00586-019-06228-2
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DOI: https://doi.org/10.1007/s00586-019-06228-2