Psychological characteristics and the effectiveness of patient-controlled analgesia.

We have evaluated the level of state and trait anxiety, neuroticism, extroversion and coping style as predictors of the effectiveness of patient-controlled analgesia (PCA) in 110 patients undergoing total abdominal hysterectomy. After operation patients were allocated to receive pain control with either PCA or i.m. injections (IMI). Pain was assessed using the short form McGill pain questionnaire at 6, 18 and 24 h after operation, and by recording the amount of analgesic consumed in the first 24 h after surgery. Both state anxiety and coping style were significant predictors of postoperative pain, irrespective of the method of analgesia used. Patients using PCA experienced significantly better pain control than those receiving IMI. However, it was those with high levels of state anxiety who experienced the greatest reduction in pain with PCA. In addition to achieving better pain control, patients who received PCA used significantly less analgesia and were discharged earlier than patients who received IMI.