Pain sensitivity and pain scoring in patients with morbid obesity.

Background: There are indications that pain perception is altered in patients with obesity, which complicates postoperative pain treatment. An essential part for adequate pain treatment is the capacity of the patient to grade pain.

Objectives: The aim of this study was to identify the differences in pain perception and pain processing in patients with without obesity.

Setting: Dutch Obesity Clinic West; private practice and the Leiden University Medical Center, the Netherlands; university hospital.

Methods: Forty-one patients with severe obesity (body mass index 42.9±4.9 kg/m) and 35 control patients (body mass index 23.2±2.8 kg/m) received multiple random thermal and electrical stimuli to the skin, in intensity in between pain threshold and tolerance. The consistency of scoring was assessed by a penalty score system and stratified into good, moderate, and poor cohorts.

Results: The penalty scores differed significantly between patients with obesity and controls with higher penalty scores in patients with obesity for both nociceptive assays. Combining the results of the heat and electrical tests indicated that just 28% of the patients with obesity had a penalty score in the good cohort, indicative of consistency in grading incoming stimuli, in contrast to 60% of control patients.

Conclusion: Individuals with severe obesity displayed hypoalgesia to noxious electrical stimuli together with difficulty in grading experimental noxious thermal and electrical stimuli in between pain threshold and tolerance. We argue that the latter may have a significant effect on pain treatment and consequently needs to be taken into account when treating the patients with obesity for acute or chronic pain.