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A metabolic dysbiosis score (MDS) representing fecal concentrations of 13 microbiota-derived metabolites independently predicted 30-day mortality in patients admitted to the medical intensive care unit (MICU), according to a study published in Science Advances.

“Therefore, fecal metabolic dysbiosis represents a potentially treatable trait to improve survival in heterogeneous critically ill patients,” Bhakti K. Patel, MD, and colleagues wrote.

The study included 196 patients with non–COVID-19 respiratory failure or shock in the MICU at the University of Chicago Medical Center. Fecal samples were collected as soon as possible after MICU admission, stored, and later analyzed for microbiome compositions and quantification of microbiota-derived fecal metabolites.

Creating & Refining the MDS

The 30-day mortality rate in the cohort was 30.6%, according to the study results. However, neither taxonomic features nor single metabolites were independently associated with the outcome.

“We reasoned that a comprehensive model that integrates the fecal metabolite concentrations might be associated with 30-day mortality,” the researchers wrote. “We previously published that a fecal MDS (COVID-19 MDS), which consisted of 3 secondary bile acids (deoxycholic acid, lithocholic acid, and isodeoxycholic acid) and desaminotyrosine, was predictive of and independently associated with mortality of critically ill patients with COVID-19.”

Analysis of several possible models led to the refinement of the MDS.

“The metabolites included in the MDS belong to the families of [short-chain fatty acids], bile acids, and tryptophan metabolites,” Dr. Patel and colleagues noted. “The metabolites within these groups influence physiological processes with plausible relevance for survival.”

Predicting Mortality

The score uses fecal concentrations of 13 microbiota-derived metabolites to accurately predict 30-day mortality after MICU admission, independent of known confounders, according to the findings.

“It is notable that in this context, relatively higher concentrations of metabolites were not always associated with survivorship. For example, an increase in indole-3-lactate was associated with mortality, contrary to the other two indoles in the score for which low concentrations were associated with mortality (indoles: indole-3-propionate and indole-3-carboxaldehyde),” the researchers wrote. “Similar patterns were also found in the group of nonindole tryptophan metabolites.”

The MDS could potentially serve as a biomarker to identify patients who may benefit from fecal metabolic dysbiosis correction, according to Dr. Patel and colleagues. However, confirmation in other cohorts of critically ill patients is necessary.