Patients with severe obesity may have greater difficulty perceiving and grading pain than do average-weight patients. Those with severe obesity display hypoalgesia when exposed to random noxious stimuli, according to Bart Torensma and his associates.

In the study, 43 patients with severe obesity and 38 controls were enrolled, of whom 41 and 35 participated. Results found the penalty scores, a tool developed to assess perception and grading of pain, differed significantly with higher penalty scores in patients with obesity for both nociceptive assays (heat pain; P = .01, electrical pain; P = .03). “We observed that participants with severe obesity had higher electrical pain threshold and tolerance values, compared with control patients, an indication of lower sensitivity to electrical pain,” the investigators wrote.

In patients with obesity the penalty scores ranged from 1.5 to 13.5 (heat pain) and from 1.0 to 12.5 (electrical pain). But penalty score distribution differed significantly between study groups for electrical pain, with penalty scores greater than 3.5 in 47.3% in patients with obesity versus 22.9% of controls (P = .049). For heat pain, 46.2% of patients with obesity versus 28.6% of control participants had penalty scores greater than 3.5 (P = .15).

“Compared with patients without obesity, patients with obesity displayed hypoalgesia to noxious electrical stimuli together with difficulty in grading experimental noxious thermal and electrical stimuli in between pain threshold and tolerance,” researchers concluded. “We argue that the latter may have a significant effect on pain treatment and consequently needs to be taken into account when treating patients with obesity for acute or chronic pain.”

Read the full study in Surgery for Obesity and Related Diseases ( doi: 10.1016/j.soard.2017.01.015 ).