Title Page

Contents

Abstract 8

Abbreviations 10

1. INTRODUCTION 11

2. MATERIALS AND METHODS 13

3. RESULTS 16

4. DISCUSSION 21

5. CONCLUSIONS 25

References 27

논문요약 33

Table 1. Information on morphine equivalent dose of opioids used in this study 35

Table 2. Cox's proportional hazard model on the first time point of the NRS ≥ 4 36

Table 3. Linear regression model predicting the total sum of NRSs ≥4 37

Table 4. Linear regression model predicting the total dose of opioid use 38

Table 5. Results of correlation analyses 39

Table 6. Summary of seven linear regression models 40

Table 7. Linear regression model predicting the sum of NRSs ≥4 on the surgery day 41

Table 8. Linear regression model predicting the sum of NRSs ≥4 on postoperative day one 42

Table 9. Linear regression model predicting the sum of NRSs ≥4 on postoperative day two 43

Table 10. Linear regression model predicting the sum of NRSs ≥4 on postoperative day three 44

Table 11. Linear regression model predicting the sum of NRSs ≥4 on postoperative day four 45

Table 12. Linear regression model predicting the sum of NRSs ≥4 on postoperative day five 46

Figure 1. Sum of NRSs ≥4 according to postoperative days 47

Figure 2. Dose of opioid use according to postoperative days 48