Correspondence  |   August 2016
Survival Advantage with Total Intravenous Anesthesia in Cancer Surgery: Is This Confounded by Cancer Type and Stage?
Author Notes
  • University of Nottingham, Royal Derby Hospital, Derby, England (B.D.). dr.doleman@gmail.com
  • (Accepted for publication March 28, 2016.)
    (Accepted for publication March 28, 2016.)×
Article Information
Correspondence
Correspondence   |   August 2016
Survival Advantage with Total Intravenous Anesthesia in Cancer Surgery: Is This Confounded by Cancer Type and Stage?
Anesthesiology 8 2016, Vol.125, 417. doi:10.1097/ALN.0000000000001173
Anesthesiology 8 2016, Vol.125, 417. doi:10.1097/ALN.0000000000001173
We read with interest the article by Wigmore et al.,1  in particular the impressive survival advantage associated with the use of total IV anesthesia (TIVA) compared to inhalational anesthesia. The study incorporated a propensity score–adjusted model, which is the most robust method to control for known confounding variables in observational studies. In addition, the authors present a biologically plausible mechanism, which satisfies a criterion for causality.
However, our main concerns relate to unmeasured confounders in the association between TIVA and cancer mortality. Type of cancer has been previously documented as an important determinant of survival. For example, 5-yr survival from breast cancer may be between 80 and 90%,2  whereas for sarcoma, it is around 60%. Observing Supplemental table 1 shows imbalances in these baseline characteristics, which were not included in any propensity score–adjusted models. The values for breast cancer (18 vs. 42%; P = 0.001) and sarcoma (19 vs. 13%; P = 0.001) were both clinically and statistically significant.
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