Figure 1.
Schematic illustration of the study protocol.
(A) The day before scheduled surgery patients completed the Spielberger's State-Trait Anxiety Inventory (STAI) and Beck's Depression Inventory (BDI); (B) Then patients underwent a conditioned pain modulation paradigm in which a baseline pressure pain threshold was measured at the quadriceps muscle followed by a conditioning painful stimulus induced by a cold pressor test (CPT) (i.e., hand immersion in an ice water bath for 120 seconds). After 120 seconds of hand immersion (or upon spontaneous hand removal) the pressure pain threshold at the quadriceps muscle was reassessed. The Situational Pain Catastrophizing Scale (S-PCS) was re-administered within five minutes after cold pressor test and patients were instructed to reference the cold pressor pain while answering; (C) From postoperative days 2–5 pain-related outcomes were assessed, including postoperative movement-evoked pain intensity, morphine consumption, and an integrated analgesic assessment score based on the aforementioned; (D) Persistent postoperative pain was assessed according to responses to the Brief Pain Inventory – Short Form (BPI) at six months.
Figure 2.
Illustration of the patient selection process, reasons for exclusion and number of patients analyzed for the primary and secondary outcomes.
Table 1.
Patient Characteristics, Preoperative Predictors and Postoperative Pain-related Outcomes (N = 42).
Table 2.
Spearman's Rank Correlation Matrix for Preoperative, Perioperative, and Postoperative Study Variables Including Predictors, Confounders and Outcomes.
Table 3.
Parameter Estimates from Regression Models of Postoperative Movement-evoked Pain Intensity (NRS 0–10) against Preoperative Conditioned Pain Modulation, Situational Pain Catastrophizing, Anxiety, and Depression.
Table 4.
Parameter Estimates from Regression Models of Postoperative Consumption of Morphine Equivalents (mg/kg/day) against Conditioned Pain Modulation, Situational Pain Catastrophizing, Anxiety, and Depression.
Table 5.
Parameter Estimates from Regression Models of an Integrated Analgesic Assessment Score based on Morphine Consumption and Movement-evoked Pain Intensity Scores (−200 to +200%) against Conditioned Pain Modulation, Situational Pain Catastrophizing, Anxiety, and Depression.
Figure 3.
Preoperative situational pain catastrophizing and postoperative movement-evoked pain.
Adjusted means (filled circles) with 95% confidence intervals (continuous solid lines) of the patient's postoperative movement-evoked pain intensity (NRS 0–10) given different log-transformed values of preoperative situational pain catastrophizing (log[S-PCS]), adjusted for anxiety and depression by averaging across the values of the state part of the Spielberger's State-Trait Anxiety Inventory (STAI) and Beck's Depression Inventory (BDI) (average marginal values). The hollow circles represent overlaid scatterplots of log[S-PCS] versus postoperative movement-evoked pain intensity.
Figure 4.
Preoperative conditioned pain modulation and postoperative morphine consumption.
Adjusted means (filled circles) with 95% confidence intervals (continuous solid lines) of the patient's postoperative morphine consumption given different values of preoperative conditioned pain modulation (CPM %). The hollow circles represent overlaid scatterplots of CPM % versus postoperative morphine consumption.