Agreement between Multiple Organ Dysfunction (MOD) and interleukin (IL)-6 levels at baseline in septic patients: a post hoc analysis from the MONARCS trial

Dedicated organ dysfunction scores such as the Multiple Organ Dysfunction (MOD) score [1] objectively measure morbidity in critically ill patients. The MOD score is constructed using simple physiologic measures of dysfunction in six organ systems and correlates in a graded fashion with the ICU mortality rate. Serum interleukin (IL)-6 levels have been proposed as a biochemical marker of the severity of the multiple organ dysfunction syndrome.

Purpose

To assess the agreement of the MOD score with IL-6 levels as baseline prognostic indicators in patients enrolled in the MONARCS trial.

Methods

The MONARCS trial was a double-blind, placebo-controlled trial designed to evaluate the safety and efficacy of afelimomab, an anti-tumor necrosis factor (TNF)a antibody. Before randomization, patients were stratified by the results of a rapid semiqualitative test (Septest) measuring serum IL-6 levels. A positive (+) Septest indicates elevated IL-6 levels. An aggregate MOD score = 9 defines significant multiorgan dysfunction syndrome. Mean baseline score, percent patients with score = 9, and the strength of the agreement of each component of the aggregate MOD score were compared in the groups of patients Septest (+) and (-) at baseline. The difference (delta) between the percent of Septest (+) and (-) patients with the highest scores for each component of the MOD score was used to test the strength of agree between IL-6 levels and each organ system component of the aggregate MOD score.

Results

A total of 2634 patients were enrolled. 998 (37.9%) had elevated IL-6 levels and 1636 (62.1%) did not. Baseline mean MOD score was higher in Septest (+) patients compared to Septest (-) patients, 8.77 vs 6.64 (P < 0.001), respectively. Baseline aggregate MOD score = 9 was found in 52% of Septest (+) versus 28% test (-) patients. The cardiovascular, neurologic and respiratory components of the MOD score appeared to show the best agreement with baseline IL-6 levels.

Conclusion

Despite lack of strong agreement between certain organ system components of the MOD score, the aggregate MOD score and Septest strongly agree at baseline. By inference, therefore, the results suggest that the Septest might also be a useful marker for ICU mortality.

Table 1