A comparison of pain rating scales by sampling from clinical trial data.

OBJECTIVE: The goals of this study were to examine agreement and estimate differences in sensitivity between pain assessment scales. DESIGN: Multiple simultaneous pain assessments by patients in acute pain after oral surgery were used to compare a four-category verbal rating scale (VRS-4) and an 11-point numeric rating scale (NRS-11) with a 100-mm visual analog scale (VAS). The sensitivity of the scales (i.e., their ability [power] to detect differences between treatments) was compared in a simulation model by sampling from true pairs of observations using varying treatment differences of predetermined size. RESULTS: There was considerable variability in VAS scores within each VRS-4 or NRS-11 category both between patients and for repeated measures from the same patient. Simulation experiments showed that the VAS was systematically more powerful than the VRS-4 in all simulations performed. The sensitivity of the VAS and NRS-11 was approximately equal. CONCLUSIONS: In this acute pain model, the VRS-4 was less sensitive than the VAS. The simulation results demonstrated similar sensitivity of the NRS-11 and VAS when comparing acute postoperative pain intensity. The choice between the VAS and NRS-11 can thus be based on subjective preferences.

Combining diclofenac with acetaminophen or acetaminophen-codeine after oral surgery: a randomized, double-blind single-dose study.

In a randomized double-blind study, 120 patients with moderate to strong pain after surgical removal of wisdom teeth were given the following in single oral doses: 100-mg enteric-coated diclofenac tablets; 1 g acetaminophen (INN, paracetamol); 1 g acetaminophen plus 60 mg codeine; 100-mg enteric-coated diclofenac tablets plus 1 g acetaminophen; or 100-mg enteric-coated diclofenac tablets plus 1 g acetaminophen plus 60 mg codeine. Patients recorded pain intensity and pain relief for 8 hours. Upside assay sensitivity was confirmed because acetaminophen plus codeine was superior to acetaminophen. Diclofenac plus acetaminophen with and without codeine had superior analgesic effect compared with diclofenac, acetaminophen, or acetaminophen plus codeine. Addition of 60 mg codeine increased the degree of side effects. These results support the clinical practice of combining diclofenac with acetaminophen for acute pain. Of clinical importance are superior and prolonged analgesia and fewer side effects after enteric-coated diclofenac tablets plus acetaminophen compared with acetaminophen plus codeine.

Variation in surgical trauma and baseline pain intensity: effects on assay sensitivity of an analgesic trial.

The aims of this study were to test the hypotheses that the type of 3rd molar removal determines baseline pain and that baseline pain influences analgesic assay sensitivity. Three groups of patients were studied: (i) 100 patients that had one fully erupted maxillary 3rd molar extracted; (ii) 95 patients that had one lower impacted 3rd molar surgically removed; and (iii) 98 patients that had two ipsilateral impacted 3rd molars surgically removed. In a randomized, double-blind fashion, the patients received (every third hour, three times) either: (i) paracetamol 1g; (ii) paracetamol 1g plus codeine 60 mg; or (iii) placebo. Baseline pain intensity (100 mm Visual Analogue Scale) was significantly lower after extraction (8 mm (2-20)) (=median (25th -75th percentile) than after surgical removal of one 3rd molar (35 mm (15-57)), which was significantly lower than pain intensity after surgical removal of two 3rd molars (49 mm (24-82)). Analgesic effects of the active test drugs were superior to placebo. Paracetamol with and without codeine could be distinguished in patients after surgical removal of one 3rd molar. In conclusion, baseline pain was related to the degree of surgical trauma, but large inter-individual variation in baseline pain intensity reduced the ability to distinguish between paracetamol with and without codeine.

Comparison of present pain intensity assessments on horizontally and vertically oriented visual analogue scales.

Contrary results have been reported from studies comparing horizontal and vertical orientations of the visual analogue scale (VAS) in non-dental pain states. The vertical orientation of the VAS has been used in our department for several years while the horizontal orientation is the most commonly used in other acute pain models. The present study investigated whether a horizontally oriented VAS is as sensitive as a vertically oriented VAS in the assessment of present pain after oral surgery. Seventy-four patients recorded their pain intensity hourly and half-hourly 15 times during 11 hours after surgery on a horizontal and on a vertical 100 mm VAS. Slightly lower mean and median values were observed at 2/3 of the observation time points for the vertical VAS compared to the horizontal VAS. The results from the two scales were compared with analysis of variance for repeated measures. No significant differences between the horizontal and the vertical VAS-values were found (p = 0.099). Distributions (Kolmogorov-Smirnov test) and dispersions of data were also similar with the two orientations of the VAS. This study shows that a vertically oriented VAS is equally sensitive as a horizontally oriented VAS in assessing present pain intensity after oral surgery.