Procalcitonin as an Early Marker of the Need for Invasive Respiratory or Vasopressor Support in Adults With Community-Acquired Pneumonia
ARTICLE REVIEW
Current challenges in the management of community-acquired pneumonia (CAP) encompass the failure of clinical signs and severity scores in the early severity assessment and risk stratification.
This study is a multicentre prospective cohort study of adults hospitalised with CAP conducted by the Centers for Disease Control and Prevention. The primary study outcome was intubation for respiratory failure or vasopressor administration for septic shock (IRVS) within 72 hours of hospital presentation. A total of 1,770 patients were included, of which 115 (6.5%) required IRVS. Serum PCT concentrations were higher in patients who required IRVS (median, 1.43 vs. 0.14 ng/mL; p<0.01). Area under the ROC curve for PCT to discriminate between patients with and those without IRVS was 0.69 (95% CI, 0.67-0.71). PCT concentration had a strong association with the risk of IRVS: Patients with PCT concentrations of 5 ng/mL-10 ng/mL were approximately three and five times more likely to require IRVS than patients with PCT < 0.05ng/mL with a linear association; although IRVS risk plateaued at PCT>10 ng/mL.
The secondary outcome was to assess whether PCT had a statistically significant additive contribution to each of the severity scores for predicting IRVS. For that they evaluated ATS minor criteria, SMART-COP and PSI in a binary “high-risk vs. low-risk” fashion. Higher PCT concentration correlated with increasing pneumonia severity at presentation as measured by the three scores in all subgroups. The addition of PCT to each of these pneumonia severity score models increased the area under the ROC curve; with a significant improvement in model fit for IRVS for each severity score (likelihood ratio test p<0.01).
It is important to keep in mind that the time to retrieve the PCT was not standardised and that the increase in AUC was modest. It is also worth highlighting that median PCT levels and IRVS rate were low, which fits in the context of a cohort where two-thirds of patients had unknown cause of pneumonia and that virus were the cause of CAP two-fold than bacteria (23% vs. 11%).
Take home message
An elevated PCT level may help identify these patients without overt clinical signs of impending respiratory failure or shock but who would benefit from early ICU admission.
Article review provided by Dr. Barbara Borgatta for the Journal Review Club on behalf of the Pneumonia-WG.
Reference
Self WH, Grijalva CG, Williams DJ, Woodworth A, Balk RA, Fakhran S, Zhu Y, Courtney DM, Chappell J, Anderson E, Qi C, Waterer GW, Trabue C, Bramley AM, Jain S, Edwards KM, Wunderink RG. Procalcitonin as an Early Marker of the Need for Invasive Respiratory or Vasopressor Support in Adults With Community-Acquired Pneumonia. Chest. 2016 Oct;150(4):819-828. doi: 10.1016/j.chest.2016.04.010. Epub 2016 Apr 21.
