Characterisation of pragmatic postoperative PAin Trajectories over seven days and their association with CHronicity after 3 months: a prospective, pilot cohort study (PATCH study)

Background Reliable outcome measurement providing information both on early and late postoperative pain outcomes are still lacking. The purpose of this study was: 1) to characterise postoperative pain trajectories according to an innovative pragmatic concept: ideal pain trajectory (rapid and sustained pain relief) vs non-ideal pain trajectories (late, transient, or no pain relief); and 2) to assess the incidence of persistent post-surgical pain (PPSP) and the potential association between non-ideal pain trajectories and PPSP. Methods This prospective observational pilot cohort study was performed from March until June 2016. A total of 344 patients undergoing major general surgery were invited to complete a self-assessment of pain intensity using numerical rating scale (NRS; 0 = no pain to 10 = worst pain) from day 1 until day 7 after surgery, in order to establish their pain trajectory. Three months after surgery, patients were screened for PPSP. Results Rest pain score was analysed in 308 participants. Among them, 210 (68% - 95% CI: 63–73) had an “ideal” pain trajectory, while 98 (32% - 95% CI: 27–37) had “non-ideal” pain trajectories. Three months after surgery, 31% (95% CI: 26–37) reported PPSP. Multivariable analysis showed that “non-ideal” pain trajectories [OR 2.25; (95% CI: 1.26–4.01) P =  0.006] were significantly associated with PPSP. Conclusions The present study proposes an innovative pragmatic concept of postoperative pain trajectories: ideal vs non-ideal pain trajectories, providing information both on acute postoperative pain resolution and early identification patients at risk for developing PPSP. Trial registration NCT02599233; November, 6, 2015, with clinicaltrials.gov.