Postoperative fatigue is a component of the emotional response to surgery: results of multivariate analysis

To test the theory that postoperative fatigue is an aspect of the emotional, not physiological, response to surgery, we examined whether fatigue is a component of subjective experience after surgery and whether it is related to subjective physical or emotional state.

Patients (N=160) undergoing hip or knee arthroplasty were assessed preoperatively, 1 and 7 days and 1 and 6 months postoperatively using multiple indicators of fatigue and subjective emotional and physical state. Covariance structure modeling was used to find out the structure of patients' experience on each occasion.

At each time, data indicated four latent variables: negative mood, positive mood, dysfunction and pain. Scales measuring fatigue indicated negative or positive mood but were unrelated to dysfunction and pain.

In surgical patients, the language of fatigue and energy describes empirically distinct components of emotional state. Explanations for postoperative fatigue should therefore be sought in emotional, not physiological, mechanisms.