Table 2. Univariate Analysis of Patient and Procedural Characteristics
Data are reported as number of patients (percentage) for categorical variables and mean ± SD for continuous variables. The odds ratio (OR) and 95% confidence interval (CI) were obtained from conditional logistic regression, taking into account the matched-pair study design.
Duration of surgery, duration of anesthesia, and use of thromboembolic prophylaxis were missing for one control, use of neuraxial analgesia was missing for two controls, and postoperative hemoglobin concentration was missing for two controls and six cases.
† OR is for every 10-year increase in age.
‡ OR is for every 5-kg/m2increase in body mass index.
§ Regional anesthesia includes intraoperative delivery of local anesthetics via the subarachnoid or epidural routes, resulting in adequate surgical anesthesia. Neuraxial analgesia includes postoperative use of continuous subarachnoid or epidural infusion of solutions containing local anesthetics and/or opioids.
# Of the 39 controls and 27 cases in the aspirin/subcutaneous heparin subgroup, only 3 (1 control, 2 cases) received subcutaneous heparin. Of the 68 controls in the warfarin/low-molecular-weight heparin subgroup, 66 received warfarin. Of the 70 cases in the warfarin/low-molecular-weight heparin subgroup, 65 are known to have received warfarin, 3 are known to have received low-molecular-weight heparin, and 2 participated in a blind study and received either warfarin or low-molecular-weight heparin.
ASA = American Society of Anesthesiologists.