Table 2

Summary of meta-analyses

Risk factorBlood transfusionTumourObesityDiabetesTobacco use
Case numberRF+SSI+39226720229340
RF+SSI−998392428 717533013 645
RF− SSI+10757695311314938
RF− SSI−62 83044 73336 39862 89354 500
Meta-analysisLogOR0.940.80.580.530.36
OR2.552.231.791.71.43
SE0.170.090.120.150.07
z5.578.85.073.55.54
P value<0.001<0.001<0.001<0.001<0.001
Heterogeneity testI20.00%0.00%67.56%64.07%0.00%
Q (df)0.17 (3)1.34 (4)11.58 (4)21.13 (7)5.78 (5)
P value0.9830.850.02<0.0010.33
Leave-one-out sensitivitylowest LogOR0.880.70.540.440.32
Highest LogOR0.960.860.660.640.43
Egger’s publication biasβ0.090.051.79−1.210.76
SE1.080.817.60.890.73
z0.080.061.12−1.350.91
P value0.9340.950.2630.1780.363
  • The presenting data of the tumour were after exclusions of outliers.

  • I² refers, Heterogeneity index; RF+, exposure to the risk factor; RF−, no exposure to the risk factor; SSI, surgical site infections; SSI+, SSI positive; SSI−, SSI negative.