C-terminal provasopressin (copeptin) in patients with community-acquired pneumonia—influence of antibiotic pre-treatment: results from the German competence network CAPNETZ

Background Recently, C-terminal provasopressin (copeptin) turned out to be predictive for mortality in community-acquired pneumonia (CAP). The aim of this study was to evaluate the influence of antibiotic pre-treatment on copeptin levels in CAP. Methods We enrolled 370 hospitalized patients (66 ± 17 years; 42% females) with proven CAP. Venous blood samples were collected at the time of inclusion into the study and as soon as possible after the diagnosis of CAP. Copeptin (B.R.A.H.M.S. AG, Henningsdorf, Germany) levels were determined in venous blood on admission. Results Eighty-five patients had antibiotic pre-treatment and 285 patients did not. Copeptin levels increased with increasing severity of CAP in patients without antibiotic pre-treatment but not in patients with antibiotic pre-treatment. Patients with prior antibiotic treatment showed significantly lower levels of copeptin [median (interquartile range): 12.8 (5.3–22.6) versus 20.8 (11.1–37.8) pmol/L, P < 0.0001] and procalcitonin [0.15 (0.07–0.38) versus 0.27 (0.10–1.52) ng/mL, P = 0.0003], but not C-reactive protein [113 (46–229) versus 122 (49–231) mg/mL, not significant] and leucocytes [12.2×103 (8.1×103–15.4×103) versus 12.5×103 (9.4×103–16.3×103) cells/mm3, not significant] compared with those without antibiotic pre-treatment. Conclusions Copeptin serum levels are higher in patients without antibiotic pre-treatment compared with those with antibiotic pre-treatment. Copeptin serum levels increase with an increasing severity of CAP in patients without, but not in patients with, antibiotic pre-treatment. Thus, antibiotic pre-treatment has to be taken into account for the correct interpretation of copeptin levels in CAP.