The role of biomarkers in community-acquired pneumonia: predicting mortality and response to adjunctive therapy

The incremental value of aspartate aminotransferase/alanine aminotransferase ratio combined with CURB-65 in predicting treatment outcomes in hospitalized adult community-acquired pneumonia patients with type 2 diabetes mellitus

BACKGROUND

The features of community-acquired pneumonia (CAP) patients with type 2 diabetes mellitus (T2DM) differ from those without. This study aims to spot a routinely tested parameter with discriminative, predictive and prognostic value to enhance CURB-65's prognostic accuracy in CAP patients with T2DM.

METHODS

We retrospectively studied consecutive CAP patients from 2020 to 2021, comparing laboratory parameters between patients with and without T2DM. Receiver operating characteristic (ROC) curve analysis, univariate and multivariate logistic regression were used to identify key parameters. The area under the ROC curve (AUC), Fagan's nomogram, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) evaluated the added predictive accuracy.

RESULTS

A total of 720 patients were included, comprising 180 diabetic CAP patients and 540 non-diabetic controls after matching for age, gender, and comorbidities through propensity score matching. In diabetic CAP patients, the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio showed the highest AUC (0.676, 95% CI, 0.575-0.776) among laboratory parameters with different distributions between the groups. AST/ALT was also identified as an independent predictor of poor treatment outcome (OR = 3.672, 95% CI, 1.455-9.268, p = 0.006). Adding AST/ALT to CURB-65 slightly increased the AUC, but remarkably enhanced NRI and IDI (AUC, 0.756 vs. 0.782, p = 0.017; continuous NRI, 0.635, 95% CI, 0.304-0.966, p < 0.001; categorical NRI, 0.175, 95% CI, 0.044-0.307, p = 0.009; IDI, 0.043, 95% CI, 0.006-0.080, p = 0.021). An AST/ALT ratio of ≥ 1.625 conferred a 74% post-test probability of poor treatment outcome, while < 1.625 predicted 21%. AST/ALT also predicted outcomes for all the CAP patients enrolled (OR = 1.771, 95% CI, 1.231-2.549, p = 0.002). Predictive accuracy improved after incorporating AST/ALP into CURB-65 in these population (AUC, 0.615 vs. 0.645, p = 0.038; continuous NRI, 0.357, 95% CI, 0.196-0.517, p < 0.001; categorical NRI, 0.264, 95% CI, 0.151-0.376, p < 0.001; IDI, 0.019, 95% CI, 0.008-0.029, p < 0.001).

CONCLUSIONS

AST/ALT was identified as a discriminative, predictive and prognostic factor for CAP patients with T2DM. The integration of AST/ALT into CURB-65 enhanced outcome prediction for both diabetic and non-diabetic CAP patients.

Discovery and predictive modeling of urine microbiome, metabolite and cytokine biomarkers in hospitalized patients with community acquired pneumonia

Pneumonia is the leading cause of infectious related death costing 12 billion dollars annually in the United States alone. Despite improvements in clinical care, total mortality remains around 4%, with inpatient mortality reaching 5–10%. For unknown reasons, mortality risk remains high even after hospital discharge and there is a need to identify those patients most at risk. Also of importance, clinical symptoms alone do not distinguish viral from bacterial infection which may delay appropriate treatment and may contribute to short-term and long-term mortality. Biomarkers have the potential to provide point of care diagnosis, identify high-risk patients, and increase our understanding of the biology of disease. However, there have been mixed results on the diagnostic performance of many of the analytes tested to date. Urine represents a largely untapped source for biomarker discovery and is highly accessible. To test this hypothesis, we collected urine from hospitalized patients with community-acquired pneumonia (CAP) and performed a comprehensive screen for urinary tract microbiota signatures, metabolite, and cytokine profiles. CAP patients were diagnosed with influenza or bacterial (Streptococcus pneumoniae and Staphylococcus aureus) etiologies and compared with healthy volunteers. Microbiome signatures showed marked shifts in taxonomic levels in patients with bacterial etiology versus influenza and CAP versus normal. Predictive modeling of 291 microbial and metabolite values achieved a + 90% accuracy with LASSO in predicting specific pneumonia etiology. This study demonstrates that urine from patients hospitalized with pneumonia may serve as a reliable and accessible sample to evaluate biomarkers that may diagnose etiology and predict clinical outcomes.

Quantile regression for survival data with covariates subject to detection limits

With advances in biomedical research, biomarkers are becoming increasingly important prognostic factors for predicting overall survival, while the measurement of biomarkers is often censored due to instruments' lower limits of detection. This leads to two types of censoring: random censoring in overall survival outcomes and fixed censoring in biomarker covariates, posing new challenges in statistical modeling and inference. Existing methods for analyzing such data focus primarily on linear regression ignoring censored responses or semiparametric accelerated failure time models with covariates under detection limits (DL). In this paper, we propose a quantile regression for survival data with covariates subject to DL. Comparing to existing methods, the proposed approach provides a more versatile tool for modeling the distribution of survival outcomes by allowing covariate effects to vary across conditional quantiles of the survival time and requiring no parametric distribution assumptions for outcome data. To estimate the quantile process of regression coefficients, we develop a novel multiple imputation approach based on another quantile regression for covariates under DL, avoiding stringent parametric restrictions on censored covariates as often assumed in the literature. Under regularity conditions, we show that the estimation procedure yields uniformly consistent and asymptotically normal estimators. Simulation results demonstrate the satisfactory finite-sample performance of the method. We also apply our method to the motivating data from a study of genetic and inflammatory markers of Sepsis.

Economic evaluation of procalcitonin-guided antibiotic therapy in acute respiratory infections: a Chinese hospital system perspective

Background:

Cost-impact models have indicated that in the USA, the use of antibiotic stewardship protocols based on procalcitonin (PCT) levels for patients with suspected acute respiratory tract infection results in cost savings. Our objective was to assess the cost impact of adopting PCT testing among patients with acute respiratory infections (ARI) from the perspective of a typical hospital system in urban China.

Methods:

To conduct an economic evaluation of PCT testing versus usual care we built a cost-impact model based on a previously published patient-level meta-analysis data of randomized trials including Chinese sites. The data were adapted to the China setting by applying the results to mean lengths of stay, costs, and practice patterns typically found in China. We estimated the annual ARI visit rate for the typical hospital system (assumed to be 1650 beds) and ARI diagnosis.

Results:

In the inpatient setting, the costs of PCT-guided care compared to usual care for a cohort of 16,405 confirmed ARI patients was almost 1.1 million Chinese yuan (CNY), compared to almost 1.8 million CNY for usual care, resulting in net savings of 721,563 CNY to a typical urban Chinese hospital system for 2015. In the ICU and outpatient settings, savings were 250,699 CNY and 2.4 million CNY, respectively. The overall annual net savings of PCT-guided care was nearly 3.4 million CNY.

Conclusions:

Substantial savings are associated with PCT protocols of ARI across common China hospital treatment settings mainly by direct reduction in unnecessary antibiotic utilization.

Clinical, Laboratory and Radiographic Features of Patients with Pneumonia and Parapneumonic Effusions

BACKGROUND:

Parapneumonic effusions complicating pneumonia are associated with increased morbidity and mortality.

AIM:

To determine the role of the clinical, laboratory and radiographic features to the differential diagnosis of patients with community- acquired pneumonia (CAP) without effusion, uncomplicated parapneumonic effusion (UCPPE) and complicated parapneumonic effusion (CPPE).

MATERIAL AND METHODS:

We analysed 148 patients with CAP without effusion, 50 with UCPPE and 44 with CPPE. In three groups of patients, the majority was male patients (58.11%, 58%, 61.36%) consequently.

RESULTS:

The chronic heart failure was the most common comorbidity in a group with CAP (28; 18.92%) and UCPPE (7; 14%), alcoholism (12;12.77%) in a group with CPPE. Patients with CPPE had significantly longer fever compared to patients with CAP without effusion (p = 0.003). Pleuritic chest pain (86.36%) and dyspnea (88.64%) were the most common symptoms in CPPE, then to group with UCPPE (60%; 52%), and in CAP without effusion (25.68%; 47,97%). Diffuse pulmonary changes were detected more frequently in the group with CAP without effusion compared with the group with CPPE (64.86 % vs. 27.27 %), while the segment lung changes were more common in patients with CPPE (50% vs. 20.27%). Patients with CPPE were significant with higher erythrocytes sedimentation rate (ESR), white blood cells (WBC) and serum C- reactive protein (CRP) than it the other two groups (p = 0.00090, p = 0.01, p= 0.000065).

CONCLUSION:

Proper analysis of clinical, laboratory and radiographic features of patients with CAP and parapneumonic effusion can prevent mismanagement in these patients and will reduce morbidity and mortality.

A novel method for rapid detection of Streptococcus pneumoniae antigens in blood

In this study, we used "RAPIRUN(®)Streptococcus pneumoniae HS (otitis media/sinusitis) (RAPIRUN-HS)," a rapid S. pneumoniae antigen detection kit, to investigate methods for detecting S. pneumoniae antigens in blood of 32 bacterial pneumonia patients. We simultaneously performed PCR to detect S. pneumoniae in blood samples. The results of these tests were compared based on pneumonia severity, determined using the Pneumonia Severity Index (PSI) score classification. Four S. pneumoniae PCR-positive patients of the six severe pneumococcal pneumonia patients (PSI risk class IV/V) also tested positive using RAPIRUN-HS. Twenty-four mild to moderate pneumonia patients (PSI risk class I-III) were S. pneumoniae PCR-negative; of these, 21 tested negative using RAPIRUN-HS. The pneumococcal pneumonia patients testing positive using RAPIRUN-HS had low leukocyte counts and elevated C-reactive protein and procalcitonin levels, indicating that RAPIRUN-HS results were correlated with pneumonia severity. The time course evaluations of the laboratory tests for severe pneumococcal pneumonia patients showed that RAPIRUN-HS and S. pneumoniae PCR yielded positive results earlier than the changes in procalcitonin and IL-6. Thus, concomitant pneumococcal bacteremia was strongly suspected in patients testing positive using RAPIRUN-HS. In conclusion, RAPIRUN-HS may be useful for determining whether to admit patients into hospitals and selecting the appropriate antimicrobial agents.

Procalcitonin, a valuable biomarker assisting clinical decision-making in the management of community-acquired pneumonia

BACKGROUND AND AIM

Community-acquired pneumonia (CAP) is a leading cause of mortality, morbidity and hospital admission, which places strain on our healthcare system. Procalcitonin (PCT) is a biomarker of bacterial infection which may help gauge the severity and prognosis of patients with CAP. In addition to clinical predictors, PCT may assist in decisions pertaining to timing of discharge from hospital and the discontinuation of antibiotics. This study aimed to determine the predictive role of PCT measurement in reducing hospital admissions, length of stay (LOS) and antibiotic (AB) usage in patients with CAP.

METHODS

A prospective, single-blinded, externally controlled study of consenting adult patients admitted with CAP. PCT levels were obtained on day 1 and day 3 (when indicated). Investigator-evaluated clinical parameters, together with results of PCT levels, determined the timing of oral AB switch and discharge from hospital. This process was compared against standard practice, but was not actually implemented, for the purpose of this study.

RESULTS

Sixty patients were included in the study. The mean age was 66.5 ± 21.2 years (56.3% male). The average Pneumonia Severity Index was 93 ± 39 (class IV) and the median CURB-65 was 2. The mean LOS for the standard practice cohort was 5.3 ± 4.6 days versus calculated LOS using the PCT guidance pathway of 3.7 ± 2.8 days. (P = 0.00006).

CONCLUSIONS

Our study supports the hypothesis that by incorporation of PCT levels, hospital admission and LOS in patients with CAP can be reduced. A randomised prospective clinical trial is planned in an attempt to help confirm these findings.

The value of mean platelet volume in the determination of community acquired pneumonia in children

BACKGROUND

Mean platelet volume (MPV) is a reflection of platelet size, which has been shown to correlate with platelet function and activation. The aim of this study was to evaluate whether MPV could be used for the diagnostic tool of community-acquired pneumonia (CAP) and for making the decision for hospitalization.

METHODS

The computerized records of children aged 1 to 18 years who were diagnosed with CAP based on WHO criteria were evaluated. A standard protocol was followed, and patients with severe CAP were hospitalized. CAP patients were divided into two groups based on disease severity. The control group consisted of age and gender matched healthy children during the study period. Values for hemoglobin, white blood cell count (WBC), platelet count, MPV and C-reactive protein (CRP) obtained on first presentation were recorded for each patient.

RESULTS

A total of 196 patients were diagnosed with CAP during the study period, 108 (55.1%) of which had severe disease, which required hospitalization (Group 1a), while the remaining 88 (44.9%) were followed-up as outpatients (Group 1b). The control group consisted of 100 healthy children (Group 2). Patients with CAP had lower MPV values than their healthy counterparts (7.1 ± 0.68 vs. 8.31 ± 1.2 fL; p<0.001). MPV value was significantly higher in hospitalized CAP patients compared to outpatients (7.32 ± 0.71 vs. 6.83 ± 0.5 fL; p=0.012). ROC curve analysis suggested that MPV level cut-off point for making a diagnosis of CAP was 8.1 fL, with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 91%, 51%, 80.8% and 70.5%, respectively.

CONCLUSIONS

Our findings suggest that MPV may be a useful predictor for diagnosed CAP but low specificity and NPV rates may lead to the false-negative diagnosis.

Innate immune function by Toll-like receptors: distinct responses in newborns and the elderly

Given the "inborn" nature of the innate immune system, it is surprising to find that innate immune function does in fact change with age. Similar patterns of distinct Toll-like-receptor-mediated immune responses come to light when one contrasts innate immune development at the beginning of life with that toward the end of life. Importantly, these developmental patterns of innate cytokine responses correlate with clinical patterns of susceptibility to disease: A heightened risk of suffering from excessive inflammation is often detected in prematurely born infants, disappears over the first few months of life, and reappears toward the end of life. In addition, risk periods for particular infections in early life reemerge in older adults. The near-mirror-image patterns that emerge in contrasts of early versus late innate immune ontogeny emphasize changes in host-environment interactions as the underlying molecular and teleologic drivers.

Epidemiology and outcome of severe pneumococcal pneumonia admitted to intensive care unit: a multicenter study

INTRODUCTION

Community-acquired pneumonia (CAP) account for a high proportion of ICU admissions, with Streptococcus pneumoniae being the main pathogen responsible for these infections. However, little is known on the clinical features and outcomes of ICU patients with pneumococcal pneumonia. The aims of this study were to provide epidemiological data and to determine risk factors of mortality in patients admitted to ICU for severe S. pneumoniae CAP.

METHODS

We performed a retrospective review of two prospectively-acquired multicentre ICU databases (2001-2008). Patients admitted for management of severe pneumococcal CAP were enrolled if they met the 2001 American Thoracic Society criteria for severe pneumonia, had life-threatening organ failure and had a positive microbiological sample for S. pneumoniae. Patients with bronchitis, aspiration pneumonia or with non-pulmonary pneumococcal infections were excluded.

RESULTS

Two hundred and twenty two patients were included, with a median SAPS II score reaching 47 [36-64]. Acute respiratory failure (n = 154) and septic shock (n = 54) were their most frequent causes of ICU admission. Septic shock occurred in 170 patients (77%) and mechanical ventilation was required in 186 patients (84%); renal replacement therapy was initiated in 70 patients (32%). Bacteraemia was diagnosed in 101 patients. The prevalence of S. pneumoniae strains with decreased susceptibility to penicillin was 39.7%. Although antibiotherapy was adequate in 92.3% of cases, hospital mortality reached 28.8%. In multivariate analysis, independent risk factors for mortality were age (OR 1.05 (95% CI: 1.02-1.08)), male sex (OR 2.83 (95% CI: 1.16-6.91)) and renal replacement therapy (OR 3.78 (95% CI: 1.71-8.36)). Co-morbidities, macrolide administration, concomitant bacteremia or penicillin susceptibility did not influence outcome.

CONCLUSIONS

In ICU, mortality of pneumococcal CAP remains high despite adequate antimicrobial treatment. Baseline demographic data and renal replacement therapy have a major impact on adverse outcome.

Early diagnosis of sepsis using serum biomarkers

Sepsis, an innate immunological response of systemic inflammation to infection, is a growing problem worldwide with a relatively high mortality rate. Immediate treatment is required, necessitating quick, early and accurate diagnosis. Rapid molecular-based tests have been developed to address this need, but still suffer some disadvantages. The most commonly studied biomarkers of sepsis are reviewed for their current uses and diagnostic accuracies, including C-reactive protein, procalcitonin, serum amyloid A, mannan and IFN-γ-inducible protein 10, as well as other potentially useful biomarkers. A singular ideal biomarker has not yet been identified; an alternative approach is to shift research focus to determine the diagnostic relevancy of multiple biomarkers when used in concert. Challenges facing biomarker research, including lack of methodology standardization and assays with better detection limits, are discussed. The ongoing efforts in the development of a multiplex point-of-care testing kit, enabling quick and reliable detection of serum biomarkers, may have great potential for early diagnosis of sepsis.

Albumin and C-reactive protein have prognostic significance in patients with community-acquired pneumonia

PURPOSE

This study aims to determine the association of commonly used biochemical markers, such as albumin and C-reactive protein (CRP), with mortality and the prognostic performance of these markers combined with the pneumonia severity index (PSI) for mortality and adverse outcomes in patients with community-acquired pneumonia (CAP).

MATERIALS AND METHODS

The data were gathered prospectively for patients hospitalized with CAP via the emergency department. Laboratory values, including CRP and albumin, clinical variables, and the PSI were measured. Primary outcomes were 28-day mortality and survival times. Secondary outcome was admission to the intensive care unit, vasopressor use, or the need for mechanical ventilation during the hospital stay.

RESULTS

A total of 424 patients were included. The 28-day mortality was 13.7%. C-reactive protein and albumin were significantly different between survivors and nonsurvivors. In logistic regression analysis, CRP and albumin were independently associated with 28-day mortality (P < .05). Receiver operating characteristic curves showed improved mortality prediction by adding CRP or albumin to the PSI scale. The Cox proportional hazards analysis showed that high serum albumin (≥3.3 mg/dL) had a hazard ratio of 0.5 (95% confidence interval, 0.3-0.9), and high CRP (≥14.3 mg/dL) had a hazard ratio of 2.0 (95% confidence interval, 1.1-3.4). For predicting secondary outcome, adding albumin to PSI increased areas under the curve significantly, but CRP did not.

CONCLUSION

Albumin and CRP were associated with 28-day mortality in hospitalized patients with CAP, and these markers increased prognostic performance when combined with the PSI scale.

Biomarkers: a definite plus in pneumonia

During the past few years, biomarkers have emerged as an indispensible tool in the diagnosis of pneumonia. To find an ideal diagnostic biomarker for pneumonia is not an easy task. Not only should it allow an early diagnosis of the condition, but it should also allow differential diagnosis from other noninfectious conditions. Ongoing research is being done in this field so as to put an array of biomarkers at the disposal of doctors to improve the diagnosis of pneumonia when patients present to them with cough or nonspecific symptoms which could easily be misinterpreted as symptoms of other conditions. Procalcitonin and soluble triggering receptor expressed on myeloid cells-1 have emerged as reliable diagnostic markers in pneumonia, and are better when compared to other markers, namely, C-reactive protein, leukocyte count, and proinflammatory cytokines. Many other biomarkers are being studied for their probable use in diagnosing pneumonia but have yet to prove their benefit.

Is procalcitonin better than C-reactive protein for early diagnosis of bacterial pneumonia in children?

Early diagnosis of bacterial pneumonia plays a pivotal role in the management. We evaluated the diagnostic accuracy of procalcitonin (PCT) as compared with C-reactive protein (CRP) for the early diagnosis of bacterial pneumonia in children. In total, 92 children consisting of 46 patients of bacterial pneumonia were admitted in the Military hospital, Rawalpindi, Pakistan and equal number of controls were included. Patient's investigations were carried out at admission. PCT and CRP were analyzed on Vidas analyzer and Immulite 1000, respectively. Out of 46 pneumonia patients, 28 were male and 18 female, with a median age of 4 years. PCT levels were significantly high median (range) of 2.69 ng/ml (0.30-13.00) vs. 0.45 ng/ml (0.10-2.00) in controls. Serum CRP levels were moderately elevated with median (range) 6.5 mg/l (0.30-60) vs. 0.30 mg/l (0.30-5.0) in controls. The area under receiver characteristic curves for PCT and CRP were 0.89 (95% CI=0.83-0.96) and 0.79 (95% CI=0.70-0.88), respectively. In total, 38 patients were diagnosed to have bacterial pneumonia with PCT (sensitivity 83% at cutoff > or = 1 ng/ml) and 26 children with CRP (sensitivity 57% at cutoff > or = 6 mg/L). PCT has better diagnostic accuracy than CRP and can be utilized for early diagnosis of bacterial pneumonia in children.

Severe community-acquired pneumonia and PIRO: a new paradigm of management

Appropriate antibiotic management and aggressive supportive therapy is not enough to improve survival in severe community-acquired pneumonia (sCAP), a systemic syndrome involving infectious organisms, inflammation, and coagulation systems. A sepsis severity staging system focused on predisposition, insult, deleterious response, and organ failure (PIRO) provides a useful basis for risk stratification and therapy. A new paradigm of management is suggested based on early identification of patients at risk, aggressive management, modulation of host response, and need for adjunctive therapy. The CAP-PIRO score is a new, simple tool stratifying patients in four categories and may be useful for early identification of patients who may benefit from adjunctive therapy.