Primary outcome: risk of bloody punctures in patients with and without thromboprophylaxis
| Patients with thromboprophylaxis* | Patients without thromboprophylaxis | P value† | |
| Peripheral blocks | |||
| Group size/no of bloody taps (%) | 9386/277/3.0 | 25,299/318/1.3 | <0.001‡ |
| Crude OR (95% CI) | 2.39 (2.03 to 2.81) | 1 | <0.001 |
| Adjusted§ OR (95% CI) | 1.60 (1.33 to 1.93) | 1 | <0.001 |
| Neuraxial blocks | |||
| Group size/no of bloody taps (%) | 11,623/349/3.0 | 19,506/591/3.0 | 0.892‡ |
| Crude OR (95% CI) | 0.99 (0.87 to 1.13) | 1 | 0.892 |
| Adjusted§ OR (95% CI) | 0.95 (0.82 to 1.10) | 1 | 0.523 |
*Any kind of antithrombotic medication before regional anesthesia block implementation.
†P value compares patients with thromboprophylaxis to patients without.
‡χ2 test used to compare proportions.
§Adjusted for year of surgery, sex, age, body mass index, American Society of Anesthesiologists physical status, use of sedative drugs or general anesthesia during block performance, catheter use versus single shot approach, multiple skin punctures, and use of ultrasound.