PRIMARY: Overall SSI
  k=13 events 112/4428 vs 225/5216 (N=9644)
  FE  OR 0.55 (0.44-0.70) Z=5.00 p=<0.001
  RE  OR 0.58 (0.41-0.84) Z=2.94 p=0.003 tau2=0.151
  Q=20.62 df=12 p=0.06 I2=42%
SECONDARY: Deep SSI (Qadir removed)
  k=11 events 60/4158 vs 139/4851 (N=9009)
  FE  OR 0.50 (0.37-0.68) Z=4.47 p=<0.001
  RE  OR 0.54 (0.32-0.91) Z=2.32 p=0.020 tau2=0.283
  Q=18.56 df=10 p=0.05 I2=46%
SECONDARY: Superficial SSI
  k=7 events 20/1668 vs 41/1883 (N=3551)
  FE  OR 0.55 (0.32-0.93) Z=2.22 p=0.027
  RE  OR 0.58 (0.34-1.00) Z=1.95 p=0.051 tau2=0.000
  Q=1.98 df=6 p=0.92 I2=0%

--- SENSITIVITY (overall SSI) ---
S1 RCTs only
  k=4 events 31/939 vs 44/1058 (N=1997)
  FE  OR 0.73 (0.45-1.18) Z=1.28 p=0.199
  RE  OR 0.79 (0.37-1.66) Z=0.62 p=0.533 tau2=0.260
  Q=5.60 df=3 p=0.13 I2=46%
S2 Non-randomised only
  k=9 events 81/3489 vs 181/4158 (N=7647)
  FE  OR 0.51 (0.39-0.66) Z=4.96 p=<0.001
  RE  OR 0.52 (0.34-0.79) Z=3.06 p=0.002 tau2=0.144
  Q=13.80 df=8 p=0.09 I2=42%
S3 Excluding zero-event studies
  k=12 events 112/4372 vs 218/5162 (N=9534)
  FE  OR 0.57 (0.45-0.72) Z=4.67 p=<0.001
  RE  OR 0.60 (0.43-0.85) Z=2.86 p=0.004 tau2=0.125
  Q=17.99 df=11 p=0.08 I2=39%
S4 Excluding serious RoB (Hey 2017)
  k=12 events 111/4311 vs 208/4944 (N=9255)
  FE  OR 0.58 (0.45-0.73) Z=4.61 p=<0.001
  RE  OR 0.61 (0.43-0.87) Z=2.75 p=0.006 tau2=0.134
  Q=18.39 df=11 p=0.07 I2=40%
S5 Excluding reviewer-flagged (Hill 2014, Chotai 2017)
  k=11 events 87/3063 vs 174/3479 (N=6542)
  FE  OR 0.54 (0.41-0.70) Z=4.56 p=<0.001
  RE  OR 0.58 (0.36-0.92) Z=2.31 p=0.021 tau2=0.251
  Q=20.22 df=10 p=0.03 I2=51%
S6 Excluding non-CDC definitions (Mirzashahi, Salimi, Khalid)
  k=10 events 88/4009 vs 190/4802 (N=8811)
  FE  OR 0.53 (0.41-0.69) Z=4.80 p=<0.001
  RE  OR 0.56 (0.38-0.82) Z=2.98 p=0.003 tau2=0.120
  Q=14.36 df=9 p=0.11 I2=37%
S7 Leave-one-out largest (Chotai 2017)
  k=12 events 92/3213 vs 185/3629 (N=6842)
  FE  OR 0.53 (0.41-0.69) Z=4.79 p=<0.001
  RE  OR 0.57 (0.37-0.87) Z=2.63 p=0.009 tau2=0.212
  Q=20.43 df=11 p=0.04 I2=46%

--- EGGER (overall SSI) ---
intercept=-0.62 (SE 0.78) t=-0.79 df=11 p=0.44

--- leave-one-out (overall, FE) ---
  omit O'Neill, 2011      OR 0.57 (0.45-0.72)
  omit Tubaki, 2013       OR 0.54 (0.42-0.68)
  omit Hill, 2014         OR 0.56 (0.44-0.71)
  omit Chotai, 2017       OR 0.53 (0.41-0.69)
  omit Hey, 2017          OR 0.58 (0.45-0.73)
  omit Devin, 2018        OR 0.60 (0.46-0.78)
  omit Mirzashahi, 2018   OR 0.52 (0.41-0.66)
  omit Oktay, 2021        OR 0.56 (0.44-0.71)
  omit Ushirozako, 2021   OR 0.54 (0.42-0.69)
  omit Vakayil, 2021      OR 0.52 (0.41-0.66)
  omit Salimi, 2022       OR 0.56 (0.44-0.72)
  omit Khalid, 2023       OR 0.56 (0.44-0.71)
  omit Sonbol, 2023       OR 0.56 (0.44-0.71)