Evaluation of a rapid assay for endotoxemia: Correlation with mortality and multiorgan dysfunction

Purpose: To determine whether a simply-read monoclonal antibody based red cell agglutination assay (Simpli-Red Endotoxin Assay [SRA], AGEN, Inc.) for the detection of circulating endotoxin, performed by ICU nurses at the bedside, is useful in predicting patient outcomes. Methods: Endotoxin measurements were performed on ICU days 1 and 2 using the bed-side SRAA and the Limulus amebocyte lysate (LAL) assay (Pyrochrome, Associates of Cape Cod, Inc.). Results: 265 consecutive adult patients requiring medical ICU admission were evaluated. 143 of these patients remained in the ICU on day 2. We found no significant association between the day 1 LAL assay or the SRA and patient outcomes. On ICU day 2, a positive SRA was associated with the development of multiorgan dysfunction (see Table). Multiple logistic regression analysis identified a positive SRA on day 2 as an independent predictor of multiorgan dysfunction (adjusted odds ratio, 3.81; 95% confidence interval, 2.28 to 6.36; P=0.009). Multiorgan Multiorgan Dysfunction Dysfunction Patient Present Absent Characteristic (n=38) (n=105) Intra-abdominal Infection: 5 (13.2) 1 (1.9)* APACHE II score >20: 24 (63.2) 22 (21.0)* Severe Sepsis or Septic Shock: 20 (52.6) 27 (25.7)* Positive SRA: 13 (34.2) 16 (15.2)* Bacteremia: 11 (28.9) 15 (14.3)* Gram-negative Infection: 16 (42.1) 25 (23.8)* LAL(EU/ml): 4.4+3.8 3.6+3.3** (*P<0.05 between groups; **P=0.053) Conclusions: A rapid test that can be performed at the bedside to detect endotoxin on ICU day 2 is predictive of multiorgan dysfunction. Clinical Implications: The rapid detection of endotoxin could be useful for stratifying patients into risk categories predictive of multiorgan dysfunction.