Strengths and limitations of this study
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This meta-analysis included 56,325 patients with varicocele and 1,334,694 patients without varicocele
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The sample size was large enough to draw a reliable conclusion.
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Stratified analyses by study design and ethnicity were also performed in this meta-analysis
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We also investigated the effect of age and BMI on the severity of varicocele.
Introduction
Materials and methods
Search strategy
Inclusion and exclusion criteria
Study selection
Data extraction
Quality assessment of the included studies
Statistical analysis
Results
Study selection
Study characteristics and quality
Study | Year | Study design | Ethnicity | Country | Sample size | Age (years) | Included varicocele patients | Quality score | |
---|---|---|---|---|---|---|---|---|---|
Varicocele | Non-varicocele | ||||||||
Handel et al. [16] | 2006 | Case-control | Caucasian | USA | 1093 | 2120 | NA | Left. right and bilateral | 8 |
Kilic et al. [13] | 2007 | Case-control | Caucasian | Turkey | 52 | 100 | 14–50 | Left. right and bilateral | 7 |
Tsao et al. [19] | 2009 | Cross-sectional | Asian | China | 490 | 560 | 18–27 | Left. right and bilateral | 8 |
Chen et al. [18] | 2010 | Case-control | Asian | China | 102 | 95 | 18–50 | NA | 7 |
Farhan et al. [27] | 2010 | Case-control | Asian | Iraq | 206 | 206 | NA | Left. right and bilateral | 7 |
Chancwalters et al. [28] | 2012 | Case-control | Caucasian | USA | 330 | 749 | 18–40 | Left. right and bilateral | 7 |
Soylemez et al. [21] | 2012 | Cross-sectional | Caucasian | Turkey | 498 | 1563 | 19–34 | Left. right and bilateral | 7 |
Yigitler et al. [29] | 2012 | Cross-sectional | Caucasian | Turkey | 750 | 11,831 | 16–23 | NA | 9 |
Özçelik et al. [30] | 2013 | Case-control | Caucasian | Turkey | 75 | 100 | 20–30 | NA | 7 |
Rais et al. [31] | 2013 | Cross-sectional | Caucasian | Israel | 47,398 | 1,275,663 | 17–18 | NA | 9 |
Gokce et al. [8] | 2013 | Cross-sectional | Caucasian | Turkey | 587 | 1255 | 18–50 | Right and bilateral | 8 |
Doğantekin et al. [32] | 2014 | Cross-sectional | Caucasian | T urkey | 210 | 390 | 21–38 | Left. right and bilateral | 7 |
Bae et al. [33] | 2014 | Case-control | Asian | Korea | 211 | 102 | NA | NA | 7 |
Gorur et al. [34] | 2015 | Case-control | Caucasian | Turkey | 138 | 117 | 18–45 | NA | 7 |
Liu et al. [35] | 2015 | Case-control | Asian | China | 73 | 104 | 18–50 | NA | 7 |
Shafi et al. [36] | 2015 | Case-control | Asian | Iran | 153 | 250 | 18–40 | Left. right and bilateral | 7 |
Liu et al. [7] | 2017 | Cross-sectional | Asian | China | 1911 | 37,648 | 21–49 | Left. right and bilateral | 8 |
Pallotti et al. [3] | 2018 | Case-control | Caucasian | Italy | 2085 | 2080 | NA | Left. right and bilateral | 7 |
Age of varicocele and nonvaricocele patients
Outcomes | N | Model used | Heterogeneity | Pooled WMD | Begg’s test P | ||
---|---|---|---|---|---|---|---|
I2 (%) | P value | WMD (95 CI) | P value | ||||
Age | |||||||
Case –control study | 9 | Random-effects | 98.1 | 0.000 | −1.27 (−4.55 to 2.01) | 0.448 | |
Cross-sectional study | 3 | Random-effects | 50.4 | 0.133 | −0.01 (−0.17 to 0.15) | 0.902 | |
Caucasian | 6 | Random-effects | 99.5 | 0.000 | −1.22 (−3.65 to 1.21) | 0.325 | |
Asian | 6 | Random-effects | 0.0 | 0.691 | −0.07 (− 0.30 to 0.16) | 0.542 | |
Overall | 12 | Fixed-effects | 98.9 | 0.000 | −0.93 (−2.19 to 0.33) | 0.149 | 0.446 |
height | |||||||
Case –control study | 5 | Random-effects | 54.4 | 0.067 | 2.19 (0.91 to 3.47) | 0.001 | |
Cross-sectional study | 5 | Random-effects | 82.7 | 0.000 | 1.30 (0.96 to 1.63) | 0.000 | |
Caucasian | 6 | Random-effects | 67.6 | 0.009 | 1.37 (0.94 to 1.79) | 0.000 | |
Asian | 4 | Random-effects | 79.2 | 0.002 | 1.79 (0.75 to 2.82) | 0.001 | |
Overall | 10 | Random-effects | 73.5 | 0.000 | 1.41 (1.07 to 1.74) | 0.000 | 0.681 |
weight | |||||||
Case –control study | 5 | Random-effects | 86.6 | 0.000 | −0.63 (−4.19 to 2.93) | 0.729 | |
Cross-sectional study | 2 | Random-effects | 97.8 | 0.000 | 2.08 (−2.91 to 7.08) | 0.414 | |
Caucasian | 4 | Random-effects | 89.7 | 0.000 | −0.05 (−3.31 to 3.20) | 0.975 | |
Asian | 3 | Random-effects | 91.7 | 0.000 | 0.51 (−4.36 to 5.39) | 0.837 | |
Overall | 7 | Random-effects | 92.2 | 0.000 | 0.24 (−2.24 to 2.72) | 0.850 | 0.746 |
BMI | |||||||
Case –control study | 11 | Random-effects | 94.3 | 0.000 | −.1.38 (−2.06 to −0.70) | 0.000 | |
Cross-sectional study | 6 | Random-effects | 97.3 | 0.000 | −1.29 (−1.69 to −0.89) | 0.000 | |
Caucasian | 10 | Random-effects | 97.3 | 0.000 | −1.07 (−1.49 to −0.65) | 0.000 | |
Asian | 7 | Random-effects | 94.9 | 0.000 | −1.96 (−2.91 to − 1.01) | 0.000 | |
Overall | 17 | Random-effects | 96.5 | 0.000 | −1.35 (− 1.67 to − 1.03) | 0.000 | 0.097 |