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Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-analysis: methodological issues

International Journal of Impotence Research volume 29, page 262 (2017)Cite this article

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We read with interest the systematic review and meta-analysis, which was published in International Journal of Impotence Research by Liu et al.1 They assessed the association between chronic periodontitis (CP) and the risk of erectile dysfunction (ED). They used the meta-analysis to obtain a summary measure of association between CP and ED. However, there are some methodological concerns regarding this meta-analysis. First, in the systematic review, they searched only three databases including PubMed, Embase and Cochrane library. Other databases such as Web of sciences and Scopus were not searched. So, some interesting studies for this systematic review may be missed, that may lead to the risk of selection bias.

Second, they included five studies in the meta-analysis with different study design (one cohort, two case–control, one randomized controlled trial (RCT) and one cross-sectional study), and estimated a pooled summary measure for the association of CP and ED (odds ratio=2.28, 95% confidence interval: 1.50–3.48). The designs of the included studies are different, and different bias can affect the results of each study designs.2 Therefore, combination of the various effect measures of case–control, cohort, cross-sectional and RCT can lead to biased results and should not be pooled in a meta-analysis.3 Therefore, they should be conducted in the subgroup analysis by the design of included studies. Third, the range of sample size of included studies is from 88 participants in a cross-sectional study by Matsumoto et al.4 to 197 136 participants in a case–control study by Keller et al.,5 so the small study effect bias can affect the results.6 In overall, because of the mentioned methodological concerns, the results of this meta-analysis should be interpreted as more cautious.

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References

  1. Liu LH, Li EM, Zhong SL, Li YQ, Yang ZY, Kang R et al. Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-analysis. Int J Impot Res 2016; 29: 43–48.

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  2. Rothman KJ, Greenland S . Validity in epidemiologic studies. In: Rothman KJ, Greenland S, Lash TL (eds). Modern Epidemiology, 3rd edn. Lippincott Williams & Wilkins: Philadelphia, PA, USA, 2008, pp 128–147.

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  3. Higgins JPT, Green S (eds) Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. The Cochrane Collaboration. Wiley Blackwell: Hoboken, NJ, 2011 Available at: http://handbook.cochrane.org.

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  4. Matsumoto S, Matsuda M, Takekawa M, Okada M, Hashizume K, Wada N et al. Association of ED with chronic periodontal disease. Int J Impot Res 2014; 26: 13–15.

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  5. Keller JJ, Chung SD, Lin HC . A nationwide population-based study on the association between chronic periodontitis and erectile dysfunction. J Clin Periodontol 2012; 39: 507–512.

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  6. Zhang Z, Xu X, Ni H . Small studies may overestimate the effect sizes in critical care meta-analyses: a meta-epidemiological study. Crit Care 2013; 17: R2.

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Acknowledgements

We thank from Department of Epidemiology and Biostatistics of School of Public Health in Tehran University of Medical Sciences.

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  1. Department of Epidemiology, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran

    Z Cheraghi & A Doosti-Irani

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  1. Z Cheraghi
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  2. A Doosti-Irani
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Correspondence to A Doosti-Irani.

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Cheraghi, Z., Doosti-Irani, A. Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-analysis: methodological issues. Int J Impot Res 29, 262 (2017). https://doi.org/10.1038/ijir.2017.33

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