Abstract
Objective: The concentration of nerve growth factor（NGF）obtained from venous leg ulcer（VLU）exudate was negatively correlated with wound pain in a previous study. The aim of this study was to verify the pathophysiological meaning of NGF as a pain biomarker by using infrared thermographic assessment.
Methods: Patients with VLU were recruited in this cross-sectional observational study. During routine wound care, thermal images of the wound and periwound area, and VLU exudate samples were taken. Thermal images were classified according to the periwound temperature pattern into two groups, “normal temperature” or “high temperature”, following a previously established method. NGF concentrations in the VLU exudate, measured with ELISA and standardized according to wound area, were compared between groups. The study protocol was approved by an ethical review board（#10389-2）.
Results: Among twenty-eight samples obtained from 13 participants, six were classified as normal temperature and 22 as high temperature. NGF concentrations in the high temperature group were significantly lower than those in the normal temperature group［medians（normal, high）=（3.36, 0.67）, z = -2.30, P = 0.02］. Even when concentrations were stratified by medians of age and wound area, which were non-significantly different between groups, the magnitude relationships of the medians of concentrations between groups were consistent with the results of whole samples.
Conclusion: NGF concentrations in VLU exudate were associated with inflammation along with temperature increase caused by the VLU.
