Protein Biomarker Linked to Delirium Duration

A protein biomarker appears to be linked to the duration of delirium and may have important implications for refining future delirium treatment in critically ill patients in intensive care units (ICU).

The calcium binding protein B (S100β) has previously been identified as a marker associated with delirium, and a study has now linked it to the duration of delirium in critically ill patients who suffer from the acute confusion and disorientation characteristic of delirium.


Scientists at the Indiana University School of Medicine (Indianapolis, IN, USA) performed a prospective observational cohort study on 63 delirious patients who were selected for the analysis, with two blood samples for S100β collected on days one and eight of enrollment.

S100β levels were measured in duplicate using a prevalidated commercially available assay kit (DiaSorin S.p.A.; Saluggia, Italy). This kit employs a two-site one-step enzyme linked immunosorbent assay and includes two positive controls of known concentration (one with less than 1.0 ng/mL and the other with more than 2.0 ng/mL of pure S100β antigen), as well as a negative control in every run. Normal values for S100β were established as below 0.10 ng/mL based on a previously published study of 200 healthy volunteers who showed a median plasma concentration of 0.052 ng/mL.

The investigators found that found that ICU patients with abnormally elevated levels of S100β either on day one or day eight, or both, had higher delirium duration compared to patients with normal S100β levels on both days. Adjusting for age, gender, race and other medical conditions, hospitalized patients with delirium have stays that are more than twice as long. They have a greater probability of being discharged to a long-term-care facility, and have a much higher probability of developing dementia than patients who do not experience delirium.

Babar Ali Khan, MD, who led the study, said, “Utilizing a simple blood test presents an easy and real opportunity to decrease the burden of the syndrome and thereby diminish progression to cognitive impairment in older adults. Since every day with delirium in the ICU is associated with a 10% increased likelihood of death, it's critical to diminish its duration and ultimately prevent it.” The study was published in the December 2013 issue of the International Journal of General Medicine.

Related Links:
Indiana University School of Medicine
DiaSorin