Plasma DNA as a marker for post-traumatic acute lung injury

Abstract

Highly sensitive and specific predictors of post-traumatic complications allow early risk-stratification of trauma patients. The purpose of this study was to investigate the potential of cell-free (plasma) DNA as an early predictor of post-traumatic acute lung injury (ALI). Ethical approval was obtained from the Chinese University of Hong Kong Research Ethics Committee. Blood withdrawn from patients within 4 hours of injury (median 60 minutes; range 30 – 240; IQR 50 – 90) was analysed using real time polymerase chain reaction (PCR) to quantify the plasma DNA. Median plasma DNA results from patients (median age 37 years, range 12 to 86; 83% male) and controls were as follows: control (n 5 30) – 3154 genome-equivalents/mL, ‘minor’ (n 5 48, ISS 1-14) – 16311 genome-equivalents/mL, major (n 5 37, ISS $ 16) 2 181303 genomeequivalents/mL (Kruskal-Wallis test p ,0.0001; a 58-fold increase between major and control values). In the major trauma group alone, median plasma DNA values in ALI-ve and ALI1ve subjects was 144563 genome-equivalents/mL and 398225 genome-equivalents/mL (Mann-Whitney (MW) test p,0.05). The area under the Receiver Operator Characteristic (ROC) curves for ALI was 0.88 (95% confidence limits (CI) 0.79 2 0.94). For ALI, plasma DNA values of .230 000 genome-equivalents/mL gave a sensitivity of 100% (CI 100.0 – 100.0), a specificity of 81% (CI 70.6 – 89.0) and a positive likelihood ratio of 5.27. Cell-free plasma DNA quantified using real time PCR may be used to whether a patient is likely to develop post-traumatic ALI.