Table 7.
CPSP risk factors: predictive model using LASSO regression
| A. Breast surgery | ||
| Predictor | OR (95% CI) | P value |
| Anxiety scale (0–10) | 1.00 (0.98 to 1.02) | 0.82 |
| HADS anxiety | 1.07 (0.94 to 1.21) | 0.31 |
| PCS before surgery | 1.02 (0.98 to 1.06) | 0.36 |
| Pain on movement POD1 | 0.88 (0.88 to 1.20) | 0.44 |
| Pain on movement POD3 | 1.18 (0.79 to 1.74) | 0.43 |
| Pain on movement POD7 | 1.01 (0.73 to 1.41) | 0.94 |
| Pain at rest POD3 | 1.32 (0.88 to 1.97) | 0.20 |
| Pain at rest POD7 | 1.39 (0.88 to 2.20) | 0.17 |
| Worst pain POD3 | 0.70 (0.55 to 0.90) | 0.006 |
| Average pain POD7 | 1.48 (0.85 to 2.56) | 0.18 |
| Pre-operative opioid | 0.71 (0.00 to > 1000) | 0.97 |
| Number of sites | 1.43 (1.08 to 1.89) | 0.02 |
| Pain relief POD1 | 1.01 (0.99 to 1.03) | 0.54 |
| Pain relief POD3 | 0.99 (0.98 to 1.02) | 0.87 |
| Pain relief POD7 | 0.99 (0.98 to 1.01) | 0.45 |
| B. Endometriosis | ||
| Predictor | OR (95% CI) | P value |
| Anxiety scale (0–10) | 0.99 (0.99 to 1.01) | 0.77 |
| HADS anxiety | 0.96 (0.87 to 1.06) | 0.45 |
| HADS depression | 1.14 (1.03 to 1.26) | 0.02 |
| IPO pain intensity before surgery | 1.09 (0.99 to 1.21) | 0.09 |
| PCS before surgery | 0.99 (0.96 to 1.03) | 0.72 |
| Pain on movement POD3 | 1.08 (0.87 to 1.35) | 0.49 |
| Pain at rest POD3 | 1.16 (0.93 to 1.44) | 0.19 |
| Pain at rest POD7 | 1.01 (0.80 to 1.26) | 0.96 |
| Worst pain POD7 | 0.94 (0.75 to 1.16) | 0.56 |
| Average pain POD3 | 1.08 (0.89 to 1.30) | 0.44 |
| Average pain POD7 | 1.51 (1.09 to 2.09) | 0.02 |
| Pre-operative opioid | 1.00 (0.99 to 1.00) | 0.95 |
| Number of sites | 1.07 (0.95 to 1.21) | 0.28 |
| Pain relief POD1 | 0.99 (0.97 to 1.00) | 0.14 |
| Pain relief POD3 | 1.00 (0.98 to 1.02) | 0.70 |
| Pain relief POD7 | 1.01 (0.99 to 1.02) | 0.50 |
| C. Sternotomy | ||
| Predictor | OR (95% CI) | P value |
| Anxiety scale | 0.99 (0.98 to 1.01) | 0.23 |
| HADS anxiety | 1.13 (1.01 to 1.26) | 0.04 |
| HADS depression | 1.00 (0.89 to 1.13) | 0.93 |
| IPO pain intensity before surgery | 1.08 (0.97 to 1.21) | 0.18 |
| PCS before surgery | 1.01 (0.98 to 1.04) | 0.49 |
| Pain during Physio POD1 | 0.91 (0.78 to 1.06) | 0.25 |
| Pain during Physio POD7 | 1.15 (0.99 to 1.32) | 0.06 |
| Pain at rest POD7 | 1.18 (0.92 to 1.49) | 0.21 |
| Average pain POD3 | 1.05 (0.85 to 1.30) | 0.67 |
| Average pain POD7 | 1.07 (0.77 to 1.49) | 0.69 |
| Pain relief POD1 | 1.00 (0.98 to 1.01) | 0.93 |
| Pain relief POD3 | 0.99 (0.97 to 1.01) | 0.29 |
| Pain relief POD7 | 0.99 (0.97 to 1.00) | 0.18 |
| D. Total knee arthroplasty | ||
| Predictor | OR (95% CI) | P value |
| Anxiety scale (0–10) | 1.00 (0.99 to 1.01) | 0.81 |
| HADS anxiety | 1.07 (0.97 to 1.18) | 0.21 |
| PCS before surgery | 0.99 (0.96 to 1.02) | 0.45 |
| Pain at rest POD1 | 1.13 (0.94 to 1.35) | 0.19 |
| Average pain POD1 | 1.01 (0.76 to 1.34) | 0.93 |
| Average pain POD3 | 1.18 (0.98 to 1.42) | 0.09 |
| Average pain POD7 | 1.26 (1.01 to 1.56) | 0.05 |
| Pre-operative opioid | 0.99 (0.97 to 1.01) | 0.34 |
| Pain relief POD3 | 1.02 (0.99 to 1.04) | 0.10 |
| Pain relief POD7 | 0.99 (0.97 to 1.01) | 0.28 |
Data are presented as odds ratio (95% confidence interval).
The LASSO regression technique selects only relevant predictors for each type of surgery and thus there are different variables in the final models for each type of surgery.
HADS, Hospital Anxiety and Depression Score; IPO, International Pain Outcome questionnaire; PCS, Pain Catastrophising scale score before surgery; POD, postoperative day.
Anxiety scale: anxiety before surgery on measured on a scale from 0 (not anxious at all) to 100 (extremely anxious).
Average pain POD1, POD3, POD7: average pain intensity on postoperative day 1, day3, and day 7 from BPI questionnaire question ‘How intense was your pain on average during the last 24 h’.
HADS anxiety: anxiety score on HADS questionnaire before surgery.
HADS depression: depression score on HADS questionnaire before surgery.
IPO intensity: pain intensity before surgery International Pain Outcome questionnaire.
Number of sites: number of sites of pre-operative pain on BPI.
Pain on movement POD1, POD3, POD7: pain on movement on postoperative day 1, day3, and day 7 with specific to the surgery; e.g. ‘How intense is your pain currently while bending your operated knee?’ for total knee arthroplasty.
Pain Physio POD1, POD7: pain during physiotherapy on postoperative day 1 and day 7.
Pain relief POD1, POD3, POD7: pain relief on BPI questionnaire on postoperative day 1, day3, and day 7.
Pain at rest POD1, POD3, POD7: pain at rest on postoperative day 1, day3, and day 7.
PCS: Pain Catastrophising scale score before surgery.
Preoperative opioid: the preoperative opioid use with equivalent in mg of morphine.
Worst pain PO3, POD7: worst pain on postoperative day 3 and day 7.