Plasma DNA concentration as a predictor of mortality and sepsis in critically ill patients

Introduction

Risk stratification of severely ill patients remains problematic, resulting in increased interest in potential circulating markers, such as cytokines, procalcitonin and brain natriuretic peptide. Recent reports have indicated the usefulness of plasma DNA as a prognostic marker in various disease states such as trauma, myocardial infarction and stroke. To our knowledge, plasma DNA has not been investigated in the setting of the critically ill patient in the intensive care setting.

Methods

Fifty-two consecutive patients were studied in a general intensive care unit. Blood samples were taken on admission and stored for further analysis. Plasma DNA levels were estimated by a PCR method using primers for the human β-haemoglobin gene. Patients were followed up to 3 months.

Results

Seventeen of the 52 patients investigated died within 3 months of sampling. Nineteen of the 52 patients developed systemic inflammatory response syndrome, sepsis or severe sepsis. Plasma DNA concentrations were found to be significantly different between patients who died and those who survived (nonsurvivors, median = 321.4 ng/ml, interquartile range [IQR] = 245.3: survivors, median = 70.7 ng/ml, IQR = 67.1, P = 0.0003). In addition, plasma DNA concentrations were found to be significantly different between patients who developed a sepsis state and those who did not (septic patients, median = 192.1 ng/ml, IQR = 298; nonseptic patients, median = 73.8 ng/ml, IQR = 110.6, P = 0.03). Receiver operator characteristic (ROC) curves were calculated for the use of plasma DNA as a predictor of death and of sepsis (see Table 1).

Table 1

Conclusions

The results presented here demonstrate that plasma DNA may be a useful prognostic marker of mortality and sepsis in critically ill patients. Further research is clearly needed in the use of this novel marker in the intensive care setting and into the possible mechanisms of release/clearance of plasma DNA in disease states.