Sepsis phenotypes, subphenotypes, and endotypes: are they ready for bedside care?

PURPOSE OF REVIEW: Sepsis remains a leading global cause of morbidity and mortality, and despite decades of research, no effective therapies have emerged. The lack of progress in sepsis outcomes is related in part to the significant heterogeneity of sepsis populations. This review seeks to highlight recent literature regarding sepsis phenotypes and the potential for further research and therapeutic intervention. RECENT FINDINGS: Numerous recent studies have elucidated various phenotypes, subphenotypes, and endotypes in sepsis. Clinical parameters including vital sign trajectories and microbial factors, biomarker investigation, and genomic, transcriptomic, proteomic, and metabolomic studies have illustrated numerous differences in sepsis populations with implications for prediction, diagnosis, treatment, and prognosis of sepsis. SUMMARY: Sepsis therapies including care bundles, fluid resuscitation, and source control procedures may be better guided by validated phenotypes than universal application. Novel biomarkers may improve upon the sensitivity and specificity of existing markers and identify complications and sequelae of sepsis. Multiomics have demonstrated significant differences in sepsis populations, most notably expanding our understanding of immunosuppressed sepsis phenotypes. Despite progress, these findings may be limited by modest reproducibility and logistical barriers to clinical implementation. Further studies may translate recent findings into bedside care.

Diagnostic Utility of a Ferritin-to-Procalcitonin Ratio to Differentiate Patients With COVID-19 From Those With Bacterial Pneumonia: A Multicenter Study.

BACKGROUND: There is an urgent need for accurate, rapid, inexpensive biomarkers that can differentiate coronavirus disease 2019 (COVID-19) from bacterial pneumonia. We assess the role of the ferritin-to-procalcitonin (F/P) ratio to classify pneumonia cases into those due to COVID-19 vs those due to bacterial pathogens. METHODS: This multicenter case-control study compared patients with COVID-19 with those with bacterial pneumonia, admitted between March 1 and May 31, 2020. Patients with COVID-19 and bacterial pneumonia co-infection were excluded. The F/P in patients with COVID-19 vs with bacterial pneumonia were compared. Receiver operating characteristic curve analysis determined the sensitivity and specificity of various cutoff F/P values for COVID-19 vs bacterial pneumonia. RESULTS: A total of 242 COVID-19 pneumonia cases and 34 bacterial pneumonia controls were included. Patients with COVID-19 pneumonia had a lower mean age (57.1 vs 64.4 years; P = .02) and a higher body mass index (30.74 vs 27.15 kg/m2; P = .02) compared with patients with bacterial pneumonia. Cases and controls had a similar proportion of women (47% vs 53%; P = .5), and COVID-19 patients had a higher prevalence of diabetes mellitus (32.6% vs 12%; P = .01). The median F/P was significantly higher in patients with COVID-19 (4037.5) compared with the F/P in bacterial pneumonia (802; P < .001). An F/P ≥877, used to diagnose COVID-19, resulted in a sensitivity of 85% and a specificity of 56%, with a positive predictive value of 93.2% and a likelihood ratio of 1.92. In multivariable analyses, an F/P ≥877 was associated with greater odds of identifying a COVID-19 case (odds ratio, 11.27; 95% CI, 4-31.2; P < .001). CONCLUSIONS: An F/P ≥877 increases the likelihood of COVID-19 pneumonia compared with bacterial pneumonia.

Diagnostic utility of a Ferritin-to-Procalcitonin Ratio to differentiate patients with COVID-19 from those with Bacterial Pneumonia: A multicenter study.

IMPORTANCE: There is a need to develop tools to differentiate COVID-19 from bacterial pneumonia at the time of clinical presentation before diagnostic testing is available. OBJECTIVE: To determine if the Ferritin-to-Procalcitonin ratio (F/P) can be used to differentiate COVID-19 from bacterial pneumonia. DESIGN: This case-control study compared patients with either COVID-19 or bacterial pneumonia, admitted between March 1 and May 31, 2020. Patients with COVID-19 and bacterial pneumonia co-infection were excluded. SETTING: A multicenter study conducted at three hospitals that included UCHealth and Phoebe Putney Memorial Hospital in the United States, and Yichang Central People's Hospital in China. PARTICIPANTS: A total of 242 cases with COVID-19 infection and 34 controls with bacterial pneumonia. MAIN OUTCOMES AND MEASURES: The F/P in patients with COVID-19 or with bacterial pneumonia were compared. Receiver operating characteristic analysis determined the sensitivity and specificity of various cut-off F/P values for the diagnosis of COVID-19 versus bacterial pneumonia. RESULTS: Patients with COVID-19 pneumonia had a lower mean age (57.11 vs 64.4 years, p=0.02) and a higher BMI (30.74 vs 27.15 kg/m 2 , p=0.02) compared to patients with bacterial pneumonia. Cases and controls had a similar proportion of women (47% vs 53%, p=0.5) and COVID-19 patients had a higher prevalence of diabetes mellitus (32.6% vs 12%, p=0.01). The median F/P was significantly higher in patients with COVID-19 (4037.5) compared to the F/P in bacterial pneumonia (802, p<0.001). An F/P ≥ 877 used to diagnose COVID-19 resulted in a sensitivity of 85% and a specificity of 56%, with a positive predictive value of 93.2%, and a likelihood ratio of 1.92. In multivariable analyses, an F/P ≥ 877 was associated with greater odds of identifying a COVID-19 case (OR: 11.27, CI: 4-31.2, p<0.001). CONCLUSIONS AND RELEVANCE: An F/P ≥ 877 increases the likelihood of COVID-19 pneumonia compared to bacterial pneumonia. Further research is needed to determine if obtaining ferritin and procalcitonin simultaneously at the time of clinical presentation has improved diagnostic value. Additional questions include whether an increased F/P and/or serial F/P associates with COVID-19 disease severity or outcomes.