Are there reliable predictors of postoperative pain?

The purpose of this study was to identify the preoperative determinants of severe postoperative pain.

Potential predictors were assessed using a questionnaire submitted on the day before surgery. Pain at rest, and pain during coughing/mobilization, were measured using visual analog scales on the day of surgery and on the following 2 days. The type of postoperative pain management was not standardized and was prescribed by the anesthesiologist in charge. Multivariate logistic regression models explaining postoperative pain were developed in Group I, comprising 304 consecutive patients undergoing orthopedic or intraperitoneal surgery, and validated in Group II, comprising 145 independent patients.

Of the 62 variables examined by univariate analysis, only five were found to increase the risk of severe postoperative pain in Group I at rest and six factors during cough/mobilization. In the multivariate model for pain at rest, general anesthesia, expectation of postoperative pain, and chronic sleeping difficulties increased the risk of severe postoperative pain. In Group II, only chronic sleeping difficulties remained (OR: 3.97, 95% Cl: 1.69-9.29). In the multivariate model during cough/mobilization, intraperitoneal surgery, fear of postoperative pain, and having a relative with a history of pain increased the risk of severe postoperative pain in Group I. Intraperitoneal surgery OR 2.45 (95% Cl = 1.01-4.50) and having a relative with a history of pain OR 2.06 (95% Cl = 1.005-4.50) remained in Group II.

Of the many factors that may influence postoperative pain, chronic sleeping difficulties emerge in this population of patients as the strongest determinant of pain at rest. Intraperitoneal surgery and having a relative with a history of pain are the strongest determinants of pain during cough/mobilization. These findings make physiological sense and deserve more attention by anesthesiologists.