What constitutes a clinically important pain reduction in patients after third molar surgery?

For patients with surgical third molar removal, it is unknown what constitutes a clinically important change in patients' visual analogue scale (VAS) reports of pain intensity.

To determine what constitutes a clinically important change in pain intensity on a VAS following surgical removal of the third molar.

The study population consisted of patients participating in three randomized trials. Patients were asked to rate their pain three times per day over a period of seven days on a 100 mm VAS after surgical removal of the third molar. Global Perceived Effect was measured on day 1 and day 7 and was used as the external criterion for assessing clinically important pain reduction. Global Perceived Effect scores of 6 ('much improved') or higher were classified as clinically 'successful', and scores of 5 ('slightly improved') or below were classified as clinically 'unsuccessful'. For each trial, the mean absolute and relative changes in VAS scores were calculated for both 'successful' and 'unsuccessful' treatments. Sensitivity and specificity analyses were performed.

The patients who reported 'successful' pain reduction showed a relative pain reduction of ≥69% and an absolute pain reduction >2.5 cm on the VAS, whereas patients who classified their pain reduction as 'unsuccessful' had a relative pain reduction of ≤18.5% and an absolute pain reduction <0.5 cm on the VAS. Furthermore, sensitivity and specificity analyses showed that a cut-off point of ≥50% relative pain reduction exhibited the best balance of sensitivity and specificity.

Relative pain reduction of ≥50% and an absolute pain reduction of ≥2.5 cm on the VAS were most accurate in predicting a successful pain reduction after a given treatment.