The cutoff value of presepsin for diagnosing sepsis increases with kidney dysfunction, a cross-sectional observational study

As presepsin levels increase with kidney dysfunction (KD), our aim was to establish cutoff points for presepsin adapted to the level of KD in order to avoid bacterial infection overdiagnosis, antibiotic overprescription, and risk of bacterial resistance. This is a unicenter retrospective study, which included all patients admitted on an emergency basis to 2 departments of a teaching hospital during a 2-year interval to whom presepsin level was determined at the emergency department prior to admission. Serum creatinine (sCrt) was employed to estimate the severity of KD using 3 thresholds (1.5, 2, and 4 mg/dL) resulting in 4 degrees of severity: KD_1, KD_2, KD_3, KD_4. There is an ascending exponential relationship between presepsin and sCrt: presepsin = 600.03e(0.212sCrt). Presepsin levels are significantly different between the patients with KD_1, KD_2, KD_3, and KD_4. In the receiver operating characteristic curves exploring the usefulness of presepsin in sepsis diagnosis, the area under the curve was satisfactory for KD_1 (0.78), KD_2 (0.78), and KD_3 (0.82), but unacceptably low for KD_4 (0.59), while the optimal cutoff points were (depending on the computational method) 700/ 982, 588/ 1125, 1065, and 2260 pg/mL for KD_1, KD_2, KD_3, and KD_4 respectively. The threshold for abnormal presepsin should be about 600, 1000, and 1300 pg/mL in patients with KD_1, KD_2, and KD_3, respectively. In patients with KD_4, presepsin has a poor discriminating power for sepsis diagnosis. If, notwithstanding, it is used for this purpose, the cutoff point should be at least at 2200.