Utility of procalcitonin as a predictor of bloodstream infections and supportive modality requirements in critically ill cancer patients

Background: We evaluated the diagnostic utility of procalcitonin (PCT) in predicting bacterial bloodstream infections (BSI) in critically ill cancer patients with and without neutropenia. We also investigated the role of PCT as a prognostic marker of supportive modalities (vasopressors, invasive mechanical ventilation, and renal replacement therapy (RRT)) in the intensive care unit (ICU). Methods: We retrospectively analyzed 2200 PCT and blood cultures from adult cancer patients with suspected sepsis. Primary outcome was BSI, defined by positive blood culture, collected within 72 h of PCT collection. Results: Median PCT values were higher in encounters with BSI (3.2 vs 0.5 ng/ml, p < 0.001). The area under the ROC curve (AUC) was 0.726 (95%CI 0.698, 0.754). PCT > 2.0 ng/ml was significantly associated with greater likelihood of BSI and this effect was significantly stronger for neutropenic (OR 9.09, 95%CI: 4.39, 18.79) compared with non-neutropenic patients (OR 4.00 (95% CI: 3.13, 5.10), interaction p = 0.036). PCT > 2.0 was associated with vasopressor requirement on ICU admission (OR 1.82 (95% CI 1.31, 2.53), p < 0.001) and RRT (OR 2.20 (95% CI 1.24, 3.91), p = 0.007). Conclusions: Procalcitonin is a fair discriminator of BSI in critically ill cancer patients with and without neutropenia and a PCT > 2.0 ng/ml was significantly more likely to require vasopressors and RRT in the ICU.