Can psychological distress be detected by response to a needle stick?

The purpose of this study was to determine whether an exaggerated response to a mildly painful stimulus would reflect abnormal levels of psychological distress in patients and, conversely, whether patients who show abnormal levels of psychological distress would have a low tolerance for a mildly painful stimulus. A total of 101 patients were given a mildly painful stimulus (30-gauge needle stick) and asked to record the amount of pain they felt on a scale of 0 to 10 (0 = no pain, 10 = severe pain). The mean response to the needle stick was a 1.9 on this scale. There was no gender difference, and the average did not change with increasing age. Psychological testing showed that 18% of the 101 patients had psychological distress prior to the needle stick. The pain ratings to needle stick of these 18 patients were not significantly different than those of patients without psychological distress (2.3 vs 1.9 on the scale). Seven percent of patients had a very low tolerance for pain (pain score of > or = 7). Evaluation of the psychological testing results on these patients showed no significant difference compared with known normal psychological values. Therefore, the assumption that patients who over-respond to a mildly painful stimulus have psychological distress is not valid. The results of this study suggest only that patients who over-respond to a needle stick have a low tolerance for pain. Furthermore, it is not valid to assume that patients who have psychological distress, poor coping abilities, or marked stress will respond in an exaggerated fashion to a mildly painful stimulus.