Variability in pain sensitivity is a well known phenomenon. The variability also extends to experimental stimuli and postoperative opioid requirement. But the report of the relationship between pain threshold and postoperative opioid requirement is very rare.

We investigated prospectively the association between pressure pain threshold and postoperative morphine requirement. We estimated pressure pain threshold by using pressure algometer and adopted PCA to treat postoperative pain.

In this study the relationship between pain threshold and postoperative opioid requirement was significant. But the correlation was weak negative (Pearson r = -0.273, P < 0.05).

Considering other associated factors which affect postoperative pain, although correlation between pain threshold and postoperative opioid requirement was significant but we concluded that clinical relevance of pain threshold is uncertain.