Identifying subtypes of a stigmatized medical condition

BackgroundSome conditions - such as obesity, depression and functional odor disorders - come with a social stigma. Understanding the etiology of these conditions helps to avoid stereotypes and find remedies. One of the major obstacles facing researchers, especially for those studying socially distressing metabolic malodor, is the difficulty in assembling biologically homogenous study cohorts. ObjectiveThe aim of this study was to examine phenotypic variance, self-reported data and laboratory tests for the purpose of identifying clinically relevant and etiologically meaningful subtypes of idiopathic body odor and the "People are Allergic To Me" (PATM) syndrome. MethodsParticipants with undiagnosed body odor conditions enrolled to participate in this research study initiated by a healthcare charity MEBO Research and sponsored by Wishart Research group at the Metabolomics Innovation Centre, University of Alberta, Canada. Primary outcomes were differences in metabolite concentrations measured in urine, blood and breath of test and control groups. Principal component analyses and other statistical tests were carried out for these measurements. ResultsWhile neither of existing laboratory tests could reliably predict chronic malodor symptoms, several measurements distinguished phenotypes at a significance level less than 5%. Types of malodor can be differentiated by self-reported consumption of (or sensitivity to) added sugars (p<0.01), blood alcohols after glucose challenge (especially ethanol: p<0.0005), urinary excretion of phenylalanine, putrescine, and combinations of blood or urine metabolites. ConclusionsOur preliminary results suggest that malodor heterogeneity can be addressed by analyses of phenotypes based on patients dietary and olfactory observations. Our studies highlight the need for more trials. Future research focused on comprehensive metabolomics and microbiome sequencing will play an important role in the diagnosis and treatment of malodor. Trial RegistrationThe study discussed in the manuscript was registered as NCT02692495 at clinicaltrials.gov. The results were compared with our earlier study registered as NCT02683876.