Correlates of postoperative pain and intravenous patient-controlled analgesia use in younger and older surgical patients

Objective. Age-related patterns in postoperative pain are unclear with reports of no age differences and less pain with age. The objective of this study was to identify correlates of pain and intravenous patient-controlled analgesia (IV PCA) morphine use in younger and older patients. Design. 24 hours after surgery, patients completed measures of pain intensity and pain qualities. Surgical factors, IV PCA morphine intake, anticholinergic load, polypharmacy, physical status, previous chronic and postoperative pain, and PCA experience were measured. Setting. Two academic general hospitals. Patients. Two hundred forty-six general surgery patients ranging in age from 18 to 82 years old. Results. In older patients, higher pain scores were associated with female gender and previous experience of postoperative PCA. In younger patients, higher pain scores were associated with female gender, previous surgery without PCA, and greater morphine intake. Lower pain was associated with being male, and no previous surgical experience in older patients, and lower morphine intake in younger patients. Morphine intake was higher in patients who were younger, had better physical status, higher anticholinergic load, and experience with PCA. Among younger patients, increased morphine use also was associated with surgical procedure and duration. Higher pain scores were more strongly associated with morphine use among younger than older patients. Conclusions. The correlates of postoperative pain and morphine use may differ with age, and the same factor may have different effects across age groups. Research is needed into the mechanisms of these age-specific profiles.