The biphasic aPTT waveform to diagnose sepsis in patients with systemic inflammatory response syndrome

Introduction

We tested the ability of the biphasic aPTT waveform to diagnosis sepsis in patients presenting to the Emergency Department (ED) with the systemic inflammatory response syndrome (SIRS). The biphasic aPTT waveform (BPW), which results from rapid complexing of VLDL and C-reactive protein during aPTT testing, has demonstrated promise as an early diagnostic test for sepsis.

Methods

A prospective, observational study was designed in which all patients presenting to the ED of an urban university hospital were screened for SIRS. Patients with SIRS unrelated to trauma or myocardial infarction were eligible. Plasma for BPW testing was obtained at the time of enrollment and daily for 7 days in admitted subjects. The primary outcome was a diagnosis of sepsis related to the presence of a BPW at enrollment. Secondary measures were mortality related to the BPW, correlation of any positive BPW with sepsis, and of the BPW with statin therapy. Two criteria for a positive test, light transmittance at 18 seconds (TL18) and the initial slope of the waveform (slope) are used. Two independent experts made the final diagnosis.

Results

We screened 5,400 consecutive admissions to the ED, identified 207 eligible subjects and enrolled 105 participants. The BPW was present at enrollment in 12 subjects by TL18 and in 28 subjects by slope. Forty-six out of 105 subjects eventually developed a BPW, 54 were diagnosed with sepsis. The sensitivity and specificity for sepsis were 17% (95% CI, 7–27.6) and 93.8% (95% CI, 87–100) by TL18 and 26.9% (95% CI, 14.9–38.9) and 71.4% (95% CI, 58.7–84.1) by slope. The positive predictive value of the test was 75 by TL18 and 50 by slope criteria. The AUC for ROC analysis of the BPW for diagnosis of sepsis is 0.469 by TL18 and 0.560 by slope. The odds ratio for developing sepsis related to any positive BPW was 2.977. The odds ratio for development of a BPW in patients on a statin at the time of presentation was 0.597. Five subjects died by 28 days, 4/5 having a BPW.

Conclusion

The BPW has no utility in the ED to predict the development of sepsis in at-risk patients. The development of a BPW at any time during the hospital stay correlates with an increased risk of sepsis and mortality. Baseline statin therapy may reduce the chance of developing a BPW.