In Reply

We thank Dr. Pivalizza for his insightful observations on our article.1 We agree that our work does not demonstrate a causal relationship between a history of opioid use and postsurgical readmission, and that our title mistakenly suggests that possibility. Because this study was observational, we expected many covariates to be differentially distributed between opioid abuse or dependence and non-opioid abuse or dependence groups. This relationship was indeed evident from table 2,1 where 29 out of 32 covariates had significantP values. However, we did not choose adjustment covariates based uponP values. We chose covariatesa priori because of the possibility that they might confound the association between opioid abuse or dependence or that they were known surrogate markers for the severity of a patient ’s postoperative condition (e.g., transfusion).2
Source: Anesthesiology - Category: Anesthesiology Source Type: research