1 research outputs found
Optimized Sampling Conditions for Fecal Volatile Organic Compound Analysis by Means of Field Asymmetric Ion Mobility Spectrometry
Fecal volatile organic
compounds (VOCs) are increasingly considered
to be potential noninvasive, diagnostic biomarkers for various gastrointestinal
diseases. Knowledge of the influence of sampling conditions on VOC
outcomes is limited. We aimed to evaluate the effects of sampling
conditions on fecal VOC profiles and to assess under which conditions
an optimal diagnostic accuracy in the discrimination between pediatric
inflammatory bowel disease (IBD) and controls could be obtained. Fecal
samples from de novo treatment-naïve pediatric IBD patients
and healthy controls (HC) were used to assess the effects of sampling
conditions compared to the standard operating procedure (reference
standard), defined as 500 mg of sample mass diluted with 10 mL tap
water, using field asymmetric ion mobility spectrometry (FAIMS). A
total of 17 IBD (15 CD (Crohn's disease) and 2 UC (ulcerative
colitis))
and 25 HC were included. IBD and HC could be discriminated with high
accuracy (accuracy = 0.93, AUC = 0.99, <i>p</i> < 0.0001).
A smaller fecal sample mass resulted in a decreased diagnostic accuracy
(300 mg accuracy = 0.77, AUC = 0.69, <i>p</i> = 0.02; 100
mg accuracy = 0.70, AUC = 0.74, <i>p</i> = 0.003). A loss
of diagnostic accuracy was seen toward increased numbers of thaw–freeze
cycles (one cycle, accuracy = 0.61, AUC = 0.80, <i>p</i> = 0.0004; two cycles, accuracy = 0.64, AUC = 0.56, <i>p</i> = 0.753; and three cycles, accuracy = 0.57, AUC = 0.50, <i>p</i> = 0.5101) and when samples were kept at room temperature
for 180 min prior to analysis (accuracy = 0.60, AUC = 0.51, <i>p</i> = 0.46). Diagnostic accuracy of VOC profiles was not significantly
influenced by storage duration differences of 20 months. The application
of a 500 mg sample mass analyzed after one thaw–freeze cycle
showed the best discriminative accuracy for the differentiation of
IBD and HC. VOC profiles and diagnostic accuracy were significantly
affected by sampling conditions, underlining the need for the implementation
of standardized protocols in fecal VOC analysis