We thank Dr. Vicendese for his interest in our article investigating the underlying reasons for socioeconomic inequalities in survival from colon cancer using causal mediation analysis (1). We acknowledge that surgical volume is not a perfect measure for quality of a hospital; therefore, we might have missed an (indirect) effect of quality on the observed socioeconomic differences in colon cancer survival due to measurement error. Dichotomizing surgical volume at the median (due to limitations of the current methods) might have also further limited our ability to detect this potential indirect effect. We did not have data on hospital characteristics such as whether they had multidisciplinary teams, specialized or high-volume surgeons, and specialist technology-based services, and the method of analysis Dr. Vicendese has proposed to overcome confounding by hospital characteristics cannot be incorporated into a causal mediation analysis; therefore, it would not address our research question.

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