Pooled ORs and definitions of preoperative predictors of poor postoperative pain control
| Preoperative predictor | No. of studies included in the pooled estimate | No. of patients | OR (95% CI) | P value | I2 statistic | Definition |
| Younger age | 14 | 5577 | 1.18 (1.05 to 1.32) | <0.001 | 79.7%* | Authors’ cut-off (range ≤31 to <70 years) |
| Female sex | 20 | 48 753 | 1.29 (1.17 to 1.43) | <0.001 | 71%* | Female sex |
| Smoking | 9 | 15 764 | 1.33 (1.09 to 1.61) | 0.005 | 55.8%* | Self-reported (any amount) |
| History of depressive symptoms | 8 | 3042 | 1.71 (1.32 to 2.21) | 0.018 | 12.6% | Self-reported, any use of antidepressants or at least moderate score on depression scale (Hamilton Depression Rating Scale≥19, Montgomery-Asberg Depression Rating Scale>13 and Geriatric Depression Scale>6) |
| History of anxiety symptoms | 10 | 2598 | 1.22 (1.09 to 1.36) | 0.001 | 82.4%* | Self-reported or moderate to severe score on anxiety scale (State Anxiety Inventory≥30 to >46, Hamilton Anxiety Scale≥25 and numeric rating scale for anxiety≥5) |
| Sleep difficulty | 2 | 549 | 2.32 (1.46 to 3.69) | <0.001 | 0% | Self-reported chronic sleep difficulties or score >5 on the Pittsburgh Sleep Quality Index |
| BMI (continuous) | 2 | 1095 | 1.02 (1.01 to 1.03) | <0.001 | 0% | BMI as a continuous variable |
| Presence of preoperative pain | 13 | 4733 | 1.21 (1.10 to 1.32) | <0.001 | 50.4%* | Self-reported, any preoperative pain |
| Preoperative analgesia use | 6 | 2448 | 1.54 (1.18 to 2.03) | 0.002 | 44.0% | Self-reported use of preoperative analgesia or opioids |
| Age (continuous) | 9 | 26 846 | 0.97 (0.93 to 1.01) | 0.16 | 93.5%* | Age as a continuous variable |
| Higher education | 8 | 2272 | 0.97 (0.69 to 1.38) | 0.89 | 43.4% | Authors’ cut-off from self-reported levels of education (range: >9 years of education to college or postgraduate degree) |
| History of surgery | 8 | 3954 | 1.15 (0.97 to 1.37) | 0.10 | 33.9% | Any self-reported previous surgical history |
| Alcohol use | 5 | 3851 | 0.89 (0.72 to 1.11) | 0.29 | 26.2% | Self-reported alcohol use (range from any to dependence) |
| Low ASA physical status | 5 | 3629 | 0.94 (0.59 to 1.51) | 0.80 | 79.0%* | ASA I compared with II or III |
| High BMI (dichotomous) | 5 | 1926 | 1.23 (0.98 to 1.55) | 0.069 | 66.5%* | Authors’ cut-off (range from >30 to >40 kg/m2) |
| Chronic pain | 4 | 1583 | 0.96 (0.65 to 1.42) | 0.84 | 59.5% | Self-reported chronic pain |
| Diabetes | 4 | 1287 | 1.02 (0.73 to 1.42) | 0.90 | 0% | Self-reported history of diabetes |
| Pain Catastrophizing Scale (continuous) | 4 | 407 | 1.02 (0.98 to 1.05) | 0.37 | 64.8%* | Pain Catastrophizing Scale scores as a continuous variable |
| Marital status | 3 | 1571 | 1.42 (0.62 to 3.23) | 0.41 | 60.1% | Self-reported as single or not married |
| Orthopaedic procedure | 3 | 10 879 | 1.06 (0.72 to 1.57) | 0.77 | 76.3%* | Orthopaedic procedure compared with abdominal surgery |
| Preoperative pressure pain tolerance | 3 | 536 | 0.85 (0.69 to 1.06) | 0.14 | 81.0%* | Preoperative pressure pain tolerance as measured by Wagner Force Ten Digital Force Gauge FPX 50 or hand-held pressure algometer (Somedic AB, Farsta, Sweden) |
| Low socioeconomic status | 2 | 1288 | 0.85 (0.49 to 1.47) | 0.56 | 0% | Brazilian Economic Classification Criteria Classes D or E or monthly family net income less than US$750 |
| Pain Catastrophizing Scale (dichotomous) | 2 | 1476 | 1.47 (0.67 to 3.22) | 0.34 | 73.0% | Authors’ cut-off (range from ≥ or >15) |
*Significant Cochran’s Q test (p<0.05).
ASA, American Society of Anesthesiologists; BMI, body mass index.