Results of generalized estimating equation (logit) regression analyses to predict persistent postoperative nonanginal pain of moderate to severe intensity over time (n = 975*)
| Variable | Crude OR (95% CI) | Adjusted OR† (95% CI) |
|---|---|---|
| Potential predictors before surgery | ||
| Female sex | 2.09 (1.50–2.91) | 1.62 (1.11–2.35) |
| Age group, yr (v. ≥ 76 yr) | ||
| 21–55 | 1.97 (1.00–3.89) | – |
| 56–65 | 1.71 (0.88–3.31) | – |
| 66–75 | 1.33 (0.68–2.63) | – |
| Education level (v. university) | ||
| Elementary school | 1.58 (0.94–2.64) | – |
| High school | 1.29 (0.83–1.99) | – |
| College or technical school | 0.94 (0.57–1.56) | – |
| Body mass index, continuous | 1.02 (0.99–1.06) | – |
| CCS grading scale of angina (v. class I)‡ | ||
| Class II | 1.35 (0.73–2.51) | 1.08 (0.56–2.09) |
| Class III | 1.67 (0.87–3.24) | 1.32 (0.65–2.69) |
| Class IV | 3.44 (1.67–7.08) | 1.81 (0.83–3.92) |
| NA | 1.17 (0.63–2.16) | 1.03 (0.54–1.96) |
| Persistent nonanginal pain before surgery (v. none) | 1.40 (1.01–1.94) | 1.20 (0.85–1.71) |
| HADS Anxiety, continuous | 1.11 (1.07–1.15) | 1.04 (0.99–1.10) |
| HADS Depression, continuous | 1.12 (1.07–1.16) | 1.00 (0.92–1.07) |
| Pain Catastrophizing Scale score, continuous | 1.04 (1.02–1.05) | 1.01 (0.99–1.03) |
| SF-12v2 mental health summary score, continuous | 0.91 (0.88–0.94) | 0.98 (0.92–1.04) |
| SF-12v2 physical health summary score, continuous | 0.90 (0.87–0.94) | 0.97 (0.92–1.02) |
| Potential predictors during or after surgery | ||
| Type of surgery (v. CABG and valve replacement) | ||
| CABG alone | 1.35 (0.80–2.28) | – |
| Valve replacement alone | 1.25 (0.70–2.23) | – |
| Duration of surgery, h, continuous | 0.88 (0.74–1.06) | – |
| Time in ICU, d, continuous | 1.07 (0.99–1.14) | 1.19 (1.05–1.36) |
| Time in hospital after discharge from ICU, d, continuous | 0.88 (0.81–0.96) | 0.86 (0.78–0.95) |
| Postoperative complications (v. none) | 0.76 (0.56–1.05) | 0.90 (0.62–1.30) |
| Average pain in previous 24 h rated as moderate to severe§ on day 3 after surgery (v. none) | 3.92 (2.69–5.70) | 2.67 (1.74–4.11) |
| Total BPI pain interference score on day 7 after surgery, continuous | 1.04 (1.03–1.06) | 1.03 (1.02–1.04) |
| Total dose of opioids¶ administered during first wk after surgery, continuous per 10-unit dose | 1.02 (1.00–1.04) | 1.00 (1.00–1.00) |
Note: BPI = Brief Pain Inventory, CABG = coronary artery bypass grafting, CCS = Canadian Cardiovascular Society, CI = confidence interval, HADS = Hospital Anxiety and Depression Scale, ICU = intensive care unit, NA = not applicable, OR = odds ratio.
↵* Data are included only for the 975 patients who provided demographic information, preoperative pain measurements, pain ratings on postoperative day 3, pain interference scores on day 7, and at least one follow-up interview at 3, 6, 12 or 24 mo after surgery.
↵† Adjusted for sex, CCS class, persistent nonanginal pain before surgery, HADS anxiety and depression scores, Pain Catastrophizing Scale score, SF-12v2 mental and physical health summary scores, time in ICU, time in hospital after discharge from ICU, average pain in previous 24 h, BPI pain interference score on day 7 and total opioid use.
↵‡ Class I = angina only during strenuous or prolonged physical activity; class II = angina only during vigorous physical activity; class III = symptoms with everyday living activities; class IV = inability to perform any activity without angina, or angina at rest.
↵§ Rating ≥ 4 out of 10 on standard numerical rating scale.
↵¶ Expressed as milligrams of parenteral morphine equivalents.