Who has surgery and why can result in surgical selection bias.
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Why Surgery is Done
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Outcome
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surgery is only done on patients with moderate or severe disease
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surgery is associated with a worse outcome
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surgery is not performed on patients with severe disease or patients with significant comorbidity
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surgery may be associated with a better outcome
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surgery is only performed on certain patients (referral bias)
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surgery is associated with a better outcome
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Surgical selection bias should be considered when:
(1) surgery is used as treatment modality
(2) not everyone has surgery or surgery is performed at different times
(3) the outcome is positively or negatively associated with surgery
(4) controlling for surgical selection bias is not explicitly performed
