Background: High intensity of acute postsurgical pain is one of the strongest predictors of chronic postsurgical pain (CPSP). We investigated if different types of patients with distinct combinations of initial pain intensity and rate of pain resolution exhibit different risks for increased pain intensity six months after surgery.
Methods: Data from 174 patients were examined using growth mixture analysis by means of structural equation modeling.
Results: Three types of patients were distinguished on the basis of acute pain trajectories. The majority of patients (57%) showed an unproblematic pattern of little initial pain on the first postoperative day, combined with further pain resolution over the four subsequent days. There also was a substantial group of patients (30%) who started out with severe pain but exhibited a high rate of pain resolution. Finally, we found a problematic group of patients (13%) who reported high pain intensities throughout all five postoperative measurements, with no signs of pain resolution. Even after controlling for preoperative pain intensity, these patients exhibited significantly higher pain intensities six months after surgery than the remaining patient groups.
Conclusions: In this study, we demonstrated that there is substantial variation in postsurgical pain trajectories, not only with regard to postsurgical initial pain intensity, but also with regard to individual rates of pain resolution. Successful pain resolution appeared to be a better predictor of absence of increased pain intensities six months after surgery than initial pain immediately after surgery. Hence, attention should be given to appropriate pain treatment in order to minimize the risk of CPSP.