Evaluating the evidence for the implementation of C-reactive protein measurement in adult patients with suspected lower respiratory tract infection in primary care: a systematic review

The Diagnostic Value of Human Neutrophilic Peptides 1-3 in Acute Pediatric Febrile Illness

Background: It is prudent to develop biomarkers that enhance the differentiation between viral and bacterial infection in order to support expeditious and judicious antimicrobial implementation in emergency department admissions. Human neutrophilic peptides 1-3 (HNP1-3) are the major neutrophilic peptides with potent antimicrobial activity. Methods: We tested the performance of the plasma HNP1-3 test in a prospective observational cohort of children admitted to the emergency department for fever. We validated this test with traditionally used biomarkers and final diagnoses. An expert panel reviewed the patient's data and gave a final diagnosis. The final diagnosis was classified as definite, probable, or possible. Results: A total of 111 children (98 with fever and 13 control) were recruited: 55% male, mean age 6.3 years. Plasma HNP1-3 levels were higher with bacterial infections: 10,428 (5789-14,866) vs. 7352 (3762-10,672) pg/mL, p = 0.007. HNP1-3 were negatively correlated with age: r = -0.207, p = 0.029. Of the different categorical variables tested, only c-reactive protein (CRP) (≥42.3 mg/dL), neutrophil count (≥10.2), and age (odds ratio = 1.185, p = 0.013 and 95%CI = 1.037-1.354) had significant diagnostic capability for bacterial disease prediction. Conclusions: Due to its low diagnostic value in febrile patients, the HNP1-3 value is not currently recommended to support pathogen differentiation in children in an emergency setting. Further studies are needed to support its clinical use.

Impact on Patient Management of a Novel Host Response Test for Distinguishing Bacterial and Viral Infections: Real World Evidence from the Urgent Care Setting

Antibiotic overuse and underuse are prevalent in urgent care settings, driven in part by diagnostic uncertainty. A host-based test for distinguishing bacterial and viral infections (MeMed BV) has been clinically validated previously. Here we examined how BV impacts antibiotic prescription in a real-world setting. The intention to treat with antibiotics before the receipt of a BV result was compared with practice after the receipt of a BV result at three urgent care centers. The analysis included 152 patients, 57.9% children and 50.7% female. In total, 131 (86.2%) had a bacterial or viral BV result. Physicians were uncertain about prescription for 38 (29.0%) patients and for 30 (78.9%) of these cases, subsequently acted in accordance with the BV result. Physicians intended to prescribe antibiotics to 39 (29.8%) patients, of whom 17 (43.6%) had bacterial BV results. Among the remaining 22 patients with viral BV results, antibiotic prescriptions were reduced by 40.9%. Overall, the physician prescribed in accordance with BV results in 81.7% of all cases (p < 0.05). In total, the physicians reported that BV supported or altered their decision making in 87.0% of cases (p < 0.05). BV impacts patient management in real-world settings, supporting appropriate antibiotic use.

AACC Guidance Document on the Clinical Use of Procalcitonin

BACKGROUND

Procalcitonin (PCT), a peptide precursor of the hormone calcitonin, is a biomarker whose serum concentrations are elevated in response to systemic inflammation caused by bacterial infection and sepsis. Clinical adoption of PCT in the United States has only recently gained traction with an increasing number of Food and Drug Administration-approved assays and expanded indications for use. There is interest in the use of PCT as an outcomes predictor as well as an antibiotic stewardship tool. However, PCT has limitations in specificity, and conclusions surrounding its utility have been mixed. Further, there is a lack of consensus regarding appropriate timing of measurements and interpretation of results. There is also a lack of method harmonization for PCT assays, and questions remain regarding whether the same clinical decision points may be used across different methods.

CONTENT

This guidance document aims to address key questions related to the use of PCT to manage adult, pediatric, and neonatal patients with suspected sepsis and/or bacterial infections, particularly respiratory infections. The document explores the evidence for PCT utility for antimicrobial therapy decisions and outcomes prediction. Additionally, the document discusses analytical and preanalytical considerations for PCT analysis and confounding factors that may affect the interpretation of PCT results.

SUMMARY

While PCT has been studied widely in various clinical settings, there is considerable variability in study designs and study populations. Evidence to support the use of PCT to guide antibiotic cessation is compelling in the critically ill and in some lower respiratory tract infections but is lacking in other clinical scenarios, and evidence is also limited in the pediatric and neonatal populations. Interpretation of PCT results requires guidance from multidisciplinary care teams of clinicians, pharmacists, and clinical laboratorians.

Biomarkers as point-of-care tests to guide prescription of antibiotics in people with acute respiratory infections in primary care

BACKGROUND

Acute respiratory infections (ARIs) are by far the most common reason for prescribing an antibiotic in primary care, even though the majority of ARIs are of viral or non-severe bacterial aetiology. It follows that in many cases antibiotic use will not be beneficial to a patient's recovery but may expose them to potential side effects. Furthermore, limiting unnecessary antibiotic use is a key factor in controlling antibiotic resistance. One strategy to reduce antibiotic use in primary care is point-of-care biomarkers. A point-of-care biomarker (test) of inflammation identifies part of the acute phase response to tissue injury regardless of the aetiology (infection, trauma, or inflammation) and may be used as a surrogate marker of infection, potentially assisting the physician in the clinical decision whether to use an antibiotic to treat ARIs. Biomarkers may guide antibiotic prescription by ruling out a serious bacterial infection and help identify patients in whom no benefit from antibiotic treatment can be anticipated. This is an update of a Cochrane Review first published in 2014.

OBJECTIVES

To assess the benefits and harms of point-of-care biomarker tests of inflammation to guide antibiotic treatment in people presenting with symptoms of acute respiratory infections in primary care settings regardless of patient age.

SEARCH METHODS

We searched CENTRAL (2022, Issue 6), MEDLINE (1946 to 14 June 2022), Embase (1974 to 14 June 2022), CINAHL (1981 to 14 June 2022), Web of Science (1955 to 14 June 2022), and LILACS (1982 to 14 June 2022). We also searched three trial registries (10 December 2021) for completed and ongoing trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in primary care patients with ARIs that compared the use of point-of-care biomarkers with standard care. We included trials that randomised individual participants, as well as trials that randomised clusters of patients (cluster-RCTs).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data on the following primary outcomes: number of participants given an antibiotic prescription at index consultation and within 28 days follow-up; participant recovery within seven days follow-up; and total mortality within 28 days follow-up. We assessed risk of bias using the Cochrane risk of bias tool and the certainty of the evidence using GRADE. We used random-effects meta-analyses when feasible. We further analysed results with considerable heterogeneity in prespecified subgroups of individual and cluster-RCTs.

MAIN RESULTS

We included seven new trials in this update, for a total of 13 included trials. Twelve trials (10,218 participants in total, 2335 of which were children) evaluated a C-reactive protein point-of-care test, and one trial (317 adult participants) evaluated a procalcitonin point-of-care test. The studies were conducted in Europe, Russia, and Asia. Overall, the included trials had a low or unclear risk of bias. However all studies were open-labelled, thereby introducing high risk of bias due to lack of blinding. The use of C-reactive protein point-of-care tests to guide antibiotic prescription likely reduces the number of participants given an antibiotic prescription, from 516 prescriptions of antibiotics per 1000 participants in the control group to 397 prescriptions of antibiotics per 1000 participants in the intervention group (risk ratio (RR) 0.77, 95% confidence interval (CI) 0.69 to 0.86; 12 trials, 10,218 participants; I² = 79%; moderate-certainty evidence).  Overall, use of C-reactive protein tests also reduce the number of participants given an antibiotic prescription within 28 days follow-up (664 prescriptions of antibiotics per 1000 participants in the control group versus 538 prescriptions of antibiotics per 1000 participants in the intervention group) (RR 0.81, 95% CI 0.76 to 0.86; 7 trials, 5091 participants; I² = 29; high-certainty evidence). The prescription of antibiotics as guided by C-reactive protein tests likely does not reduce the number of participants recovered, within seven or 28 days follow-up (567 participants recovered within seven days follow-up per 1000 participants in the control group versus 584 participants recovered within seven days follow-up per 1000 participants in the intervention group) (recovery within seven days follow-up: RR 1.03, 95% CI 0.96 to 1.12; I² = 0%; moderate-certainty evidence) (recovery within 28 days follow-up: RR 1.02, 95% CI 0.79 to 1.32; I² = 0%; moderate-certainty evidence). The use of C-reactive protein tests may not increase total mortality within 28 days follow-up, from 1 death per 1000 participants in the control group to 0 deaths per 1000 participants in the intervention group (RR 0.53, 95% CI 0.10 to 2.92; I² = 0%; low-certainty evidence). We are uncertain as to whether procalcitonin affects any of the primary or secondary outcomes because there were few participants, thereby limiting the certainty of evidence. We assessed the certainty of the evidence as moderate to high according to GRADE for the primary outcomes for C-reactive protein test, except for mortality, as there were very few deaths, thereby limiting the certainty of the evidence.

AUTHORS' CONCLUSIONS

The use of C-reactive protein point-of-care tests as an adjunct to standard care likely reduces the number of participants given an antibiotic prescription in primary care patients who present with symptoms of acute respiratory infection. The use of C-reactive protein point-of-care tests likely does not affect recovery rates. It is unlikely that further research will substantially change our conclusion regarding the reduction in number of participants given an antibiotic prescription, although the size of the estimated effect may change.  The use of C-reactive protein point-of-care tests may not increase mortality within 28 days follow-up, but there were very few events. Studies that recorded deaths and hospital admissions were performed in children from low- and middle-income countries and older adults with comorbidities.  Future studies should focus on children, immunocompromised individuals, and people aged 80 years and above with comorbidities. More studies evaluating procalcitonin and potential new biomarkers as point-of-care tests used in primary care to guide antibiotic prescription are needed.  Furthermore, studies are needed to validate C-reactive protein decision algorithms, with a specific focus on potential age group differences.

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Effects of primary care C-reactive protein point-of-care testing on antibiotic prescribing by general practice staff: pragmatic randomised controlled trial, England, 2016 and 2017

Background

C-reactive protein (CRP) testing can be used as a point-of-care test (POCT) to guide antibiotic use for acute cough.

Aim

We wanted to determine feasibility and effect of introducing CRP POCT in general practices in an area with high antibiotic prescribing for patients with acute cough and to evaluate patients’ views of the test.

Methods

We used a McNulty–Zelen cluster pragmatic randomised controlled trial design in general practices in Northern England. Eight intervention practices accepted CRP testing and eight control practices maintained usual practice. Data collection included process evaluation, patient questionnaires, practice audit and antibiotic prescribing data.

Results

Eight practices with over 47,000 patient population undertook 268 CRP tests over 6 months: 78% of patients had a CRP < 20 mg/L, 20% CRP 20–100 mg/L and 2% CRP > 100 mg/L, where 90%, 22% and 100%, respectively, followed National Institute for Health and Care Excellence (NICE) antibiotic prescribing guidance. Patients reported that CRP testing was comfortable (88%), convenient (84%), useful (92%) and explained well (85%). Patients believed CRP POCT aided clinical diagnosis, provided quick results and reduced unnecessary antibiotic use. Intervention practices had an estimated 21% reduction (95% confidence interval: 0.46–1.35) in the odds of prescribing for cough compared with the controls, a non-significant but clinically relevant reduction.

Conclusions

In routine general practice, CRP POCT use was variable. Non-significant reductions in antibiotic prescribing may reflect small sample size due to non-use of tests. While CRP POCT may be useful, primary care staff need clearer CRP guidance and action planning according to NICE guidance.

Point-of-Care C-Reactive Protein Testing to Reduce Antibiotic Prescribing for Respiratory Tract Infections in Primary Care: Systematic Review and Meta-Analysis of Randomised Controlled Trials

C-reactive protein (CRP) point-of-care testing (POCT) is increasingly being promoted to reduce diagnostic uncertainty and enhance antibiotic stewardship. In primary care, respiratory tract infections (RTIs) are the most common reason for inappropriate antibiotic prescribing, which is a major driver for antibiotic resistance. We systematically reviewed the available evidence on the impact of CRP-POCT on antibiotic prescribing for RTIs in primary care. Thirteen moderate to high-quality studies comprising 9844 participants met our inclusion criteria. Meta-analyses showed that CRP-POCT significantly reduced immediate antibiotic prescribing at the index consultation compared with usual care (RR 0.79, 95%CI 0.70 to 0.90, p = 0.0003, I² = 76%) but not during 28-day (n = 7) follow-up. The immediate effect was sustained at 12 months (n = 1). In children, CRP-POCT reduced antibiotic prescribing when CRP (cut-off) guidance was provided (n = 2). Meta-analyses showed significantly higher rates of re-consultation within 30 days (n = 8, 1 significant). Clinical recovery, resolution of symptoms, and hospital admissions were not significantly different between CRP-POCT and usual care. CRP-POCT can reduce immediate antibiotic prescribing for RTIs in primary care (number needed to (NNT) for benefit = 8) at the expense of increased re-consultations (NNT for harm = 27). The increase in re-consultations and longer-term effects of CRP-POCT need further evaluation. Overall, the benefits of CRP-POCT outweigh the potential harms (NNTnet = 11).

Accuracy and precision analysis for a biophotonic assay of C-reactive protein

A multiplexed biophotonic assay platform has been developed using the localised particle plasmon in gold nanoparticles assembled in an array and functionalised for two assays: total IgG and C-reactive protein (CRP). A protein A/G (PAG) assay, calibrated with a NIST reference material, shows a maximum surface coverage of θ_max = 7.13 ± 0.19 mRIU, equivalent to 1.5 ng mm^-2 of F(ab)-presenting antibody. The CRP capture antibody has an equivalent surface binding density of θ_max = 2.95 ± 0.41 mRIU indicating a 41% capture antibody availability. Free PAG binding to the functionalised anti-CRP surface shows that only 47 ± 3% of CRP capture antibodies are correctly presenting Fab regions for antigen capture. The accuracy and precision of the CRP sensor assay was assessed with 54 blood samples containing spiked CRP in the range 2-160 mg L^-1. The mean accuracy was 0.42 mg L^-1 with Confidence Interval (CI) at 95% from -14.7 to 13.8 mg L^-1 and the precision had a Coefficient of Variation (CV) of 10.6% with 95% CI 0.9%-20.2%. These biophotonic platform performance metrics indicate a CRP assay with 2-160 mg L^-1 dynamic range, performed in 8 minutes from 5 μL of whole blood without sample preparation.

Procalcitonin guidance in patients with lower respiratory tract infections: a systematic review and meta-analysis

Although effective for bacterial lower respiratory tract infections (LRTIs), antibiotic treatment is often incorrectly prescribed for non-bacterial LRTIs. Procalcitonin has emerged as a promising biomarker to diagnose bacterial infections and guide antibiotic treatment decisions. As part of a regulatory submission to the U.S. Food and Drug Administration, this systematic review and meta-analysis summarizes the effects of procalcitonin-guided antibiotic stewardship on antibiotic use and clinical outcomes in adult LRTI patients. PubMed and the Cochrane Database of Systematic Reviews were searched for English-language randomized controlled trials published between January 2004 and May 2016. Random and fixed effects meta-analyses were performed to study efficacy (initiation of antibiotics, antibiotic use) and safety (mortality, length of hospital stay). Eleven trials were retained, comprising 4090 patients. Procalcitonin-guided patients had lower odds of antibiotic initiation (odds ratio: 0.26; 95% confidence interval [CI]: 0.13-0.52) and shorter mean antibiotic use (weighted mean difference: -2.15 days; 95% CI: -3.30 to -0.99) compared to patients treated with standard care. Procalcitonin use had no adverse impact on mortality (relative risk: 0.94; 95% CI: 0.69-1.28) and length of hospital stay (weighted mean difference: -0.15 days; 95% CI: -0.60 to 0.30). Procalcitonin guidance reduces antibiotic initiation and use among adults with LRTIs with no apparent adverse impact on length of hospital stay or mortality.

Respiratory tract virus infections in the elderly with pneumonia

BACKGROUND

In children suffering from severe lower airway illnesses, respiratory virus detection has given good prognostic information, but such reports in the elderly are scarce. Therefore, our aim was to study whether the detection of nasopharyngeal viral pathogens and conventional inflammatory markers in the frail elderly correlate to the presence, signs and symptoms or prognosis of radiographically-verified pneumonia.

METHODS

Consecutive episodes of hospital care of patients 65 years and older with respiratory symptoms (N = 382) were prospectively studied as a cohort. Standard clinical questionnaire was filled by the study physician. Laboratory analyses included PCR diagnostics of nasopharyngeal swab samples for 14 respiratory viruses, C-reactive protein (CRP) and white blood cell count (WBC). Chest radiographs were systematically analysed by a study radiologist. The length of hospital stay, hospital revisit and death at ward were used as clinical endpoints.

RESULTS

Median age of the patients was 83 years (range 76-90). Pneumonia was diagnosed in 112/382 (29%) of the studied episodes. One or more respiratory viruses were detected in 141/382 (37%) episodes and in 34/112 (30%) episodes also diagnosed with pneumonia. Pneumonia was associated with a WBC over 15 × 10⁹/L (P = .006) and a CRP value over 80 mg/l (P < .05). A virus was detected in 30% of pneumonia episodes and in 40% of non-pneumonia episodes, but this difference was not significant (P = 0.09). The presence of a respiratory virus was associated with fewer revisits to the hospital (P < .05), whereas a CRP value over 100 mg/l was associated with death during hospital stay (P < .05). Respiratory virus detections did not correlate to WBC or CRP values, signs and symptoms or prognosis of radiographically-verified pneumonia episodes.

CONCLUSION

Among the elderly with respiratory symptoms, respiratory virus detection was not associated with an increased risk of pneumonia or with a more severe clinical course of the illness. CRP and WBC remain important indicators of pneumonia, and according to our findings, pneumonia should be treated as a bacterial disease regardless of the virus findings. Our data does not support routine virus diagnostics for the elderly patients with pneumonia outside the epidemic seasons.

Adult Outpatients With Acute Cough Due to Suspected Pneumonia or Influenza: CHEST Guideline and Expert Panel Report

BACKGROUND

Patients commonly present to primary care services with upper and lower respiratory tract infections, and guidelines to help physicians investigate and treat acute cough due to suspected pneumonia and influenza are needed.

METHODS

A systematic search was carried out with eight patient, intervention, comparison, outcome questions related to acute cough due to suspected pneumonia or influenza.

RESULTS

There was a lack of randomized controlled trials in the setting of outpatients presenting with acute cough due to suspected pneumonia or influenza who were not hospitalized. Both clinical suggestions and research recommendations were made on the evidence available and CHEST Expert Cough Panel advice.

CONCLUSIONS

For outpatient adults with acute cough due to suspected pneumonia, we suggest the following clinical symptoms and signs are suggestive of pneumonia: cough; dyspnea; pleural pain; sweating, fevers, or shivers; aches and pains; temperature ≥ 38°C; tachypnea; and new and localizing chest examination signs. Those suspected of having pneumonia should undergo chest radiography to improve diagnostic accuracy. Although the measurement of C-reactive protein levels strengthens both the diagnosis and exclusion of pneumonia, there was no added benefit of measuring procalcitonin levels in this setting. We suggest that there is no need for routine microbiological testing. We suggest the use of empiric antibiotics according to local and national guidelines when pneumonia is suspected in settings in which imaging cannot be performed. Where there is no clinical or radiographic evidence of pneumonia, we do not suggest the routine use of antibiotics. There is insufficient evidence to make recommendations for or against specific nonantibiotic, symptomatic therapies. Finally, for outpatient adults with acute cough and suspected influenza, we suggest that initiating antiviral treatment (according to Centers for Disease Control and Prevention advice) within 48 hours of symptoms could be associated with decreased antibiotic use and hospitalization and improved outcomes.

MALDI-TOF MS monitoring of PBMC activation status in sepsis

Background

MALDI-TOF mass spectrometry (MS) on whole cells enables the detection of different cell types and cell activation. Here, we wondered whether this approach would be useful to investigate the host response in sepsis.

Methods

Peripheral blood mononuclear cells (PBMCs) from patients with severe sepsis and healthy donors were analyzed with MALDI-TOF MS. PBMCs from healthy donors were also stimulated with lipopolysaccharide, peptidoglycan, CpG oligonucleotides, polyinosinic polycytidylic acid, and with heat-inactivated bacteria. Averaged spectra of PBMCs stimulated in vitro by different agonists were generated from the database using the Biotyper software and matching scores between each spectrum from patients and averaged spectra from the database were calculated.

Results

We show that the MALDI-TOF MS signature of PBMCs from septic patients was specific, compared with healthy controls. As the fingerprints observed in patients may be related to PBMC activation, PBMCs from healthy controls were stimulated with cytokines, soluble Pathogen-Associated Molecular Patterns (PAMPs) and heat-killed bacteria, and we created a database of reference spectra. The MALDI-TOF MS profiles of PBMCs from septic patients were then compared with the database. No differences were found between patients with documented infection (n = 6) and those without bacteriological documentation (n = 6). The spectra of PBMCs from septic patients matched with those of interferon-γ- and interleukin-10-stimulated PBMCs, confirming that sepsis is characterized by both inflammatory and immunoregulatory features. Interestingly, the spectra of PBMCs from septic patients without documented infection matched with the reference spectrum of PBMCs stimulated by CpG oligonucleotides, suggesting a bacterial etiology in these patients.

Conclusions

Despite the limits of this preliminary study, these results indicate that the monitoring of functional status of PBMCs in peripheral blood by whole cell MALDI-TOF MS could provide unique opportunities to assess disease progression or resolution in clinical settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3266-7) contains supplementary material, which is available to authorized users.

A host-protein signature is superior to other biomarkers for differentiating between bacterial and viral disease in patients with respiratory infection and fever without source: a prospective observational study

Bacterial and viral infections often present with similar symptoms. Etiologic misdiagnosis can alter the trajectory of patient care, including antibiotic overuse. A host-protein signature comprising tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-induced protein-10 (IP-10), and C-reactive protein (CRP) was validated recently for differentiating bacterial from viral disease. However, a focused head-to-head comparison of its diagnostic performance against other biomarker candidates for this indication was lacking in patients with respiratory infection and fever without source. We compared the signature to other biomarkers and prediction rules using specimens collected prospectively at two secondary medical centers from children and adults. Inclusion criteria included fever > 37.5 °C, symptom duration ≤ 12 days, and presentation with respiratory infection or fever without source. Comparator method was based on expert panel adjudication. Signature and biomarker cutoffs and prediction rules were predefined. Of 493 potentially eligible patients, 314 were assigned unanimous expert panel diagnosis and also had sufficient specimen volume. The resulting cohort comprised 175 (56%) viral and 139 (44%) bacterial infections. Signature sensitivity 93.5% (95% CI 89.1–97.9%), specificity 94.3% (95% CI 90.7–98.0%), or both were significantly higher (all p values < 0.01) than for CRP, procalcitonin, interleukin-6, human neutrophil lipocalin, white blood cell count, absolute neutrophil count, and prediction rules. Signature identified as viral 50/57 viral patients prescribed antibiotics, suggesting potential to reduce antibiotic overuse by 88%. The host-protein signature demonstrated superior diagnostic performance in differentiating viral from bacterial respiratory infections and fever without source. Future utility studies are warranted to validate potential to reduce antibiotic overuse.

Point-of-care testing in primary care patients with acute cardiopulmonary symptoms: a systematic review

BACKGROUND

Point-of-care tests (POCT) can assist general practitioners (GPs) in diagnosing and treating patients with acute cardiopulmonary symptoms, but it is currently unknown if POCT impact relevant clinical outcomes in these patients.

OBJECTIVE

To assess whether using POCT in primary care patients with acute cardiopulmonary symptoms leads to more accurate diagnosis and impacts clinical management.

METHODS

We performed a systematic review in four bibliographic databases. Articles published before February 2016 were screened by two reviewers. Studies evaluating the effect of GP use of POCT on clinical diagnostic accuracy and/or effect on treatment and referral rate in patients with cardiopulmonary symptoms were included.

RESULTS

Our search yielded nine papers describing data from seven studies, on the clinical diagnostic accuracy of POCT in a total of 2277 primary care patients with acute cardiopulmonary symptoms. Four papers showed data on GP use of D-dimer POCT in pulmonary embolism (two studies); two studies on Troponin T in acute coronary syndrome; one on heart-type fatty acid-binding protein (H-FABP) in acute coronary syndrome; one on B-type natriuretic peptide (BNP) in heart failure; one on 3-in-1 POCT (Troponin T, BNP, D-dimer) in acute coronary syndrome, heart failure and/or pulmonary embolism. Only one study assessed the effect of GP use of POCT on treatment initiation and one on actual referral rates.

CONCLUSION

There is currently limited and inconclusive evidence that actual GP use of POCT in primary care patients with acute cardiopulmonary symptoms leads to more accurate diagnosis and affects clinical management. However, some studies show promising results, especially when a POCT is combined with a clinical decision rule.

Validation of a Novel Assay to Distinguish Bacterial and Viral Infections

BACKGROUND

Reliably distinguishing bacterial from viral infections is often challenging, leading to antibiotic misuse. A novel assay that integrates measurements of blood-borne host-proteins (tumor necrosis factor-related apoptosis-inducing ligand, interferon γ-induced protein-10, and C-reactive protein [CRP]) was developed to assist in differentiation between bacterial and viral disease.

METHODS

We performed double-blind, multicenter assay evaluation using serum remnants collected at 5 pediatric emergency departments and 2 wards from children ≥3 months to ≤18 years without (n = 68) and with (n = 529) suspicion of acute infection. Infectious cohort inclusion criteria were fever ≥38°C and symptom duration ≤7 days. The reference standard diagnosis was based on predetermined criteria plus adjudication by experts blinded to assay results. Assay performers were blinded to the reference standard. Assay cutoffs were predefined.

RESULTS

Of 529 potentially eligible patients with suspected acute infection, 100 did not fulfill infectious inclusion criteria and 68 had insufficient serum. The resulting cohort included 361 patients, with 239 viral, 68 bacterial, and 54 indeterminate reference standard diagnoses. The assay distinguished between bacterial and viral patients with 93.8% sensitivity (95% confidence interval: 87.8%-99.8%) and 89.8% specificity (85.6%-94.0%); 11.7% had an equivocal assay outcome. The assay outperformed CRP (cutoff 40 mg/L; sensitivity 88.2% [80.4%-96.1%], specificity 73.2% [67.6%-78.9%]) and procalcitonin testing (cutoff 0.5 ng/mL; sensitivity 63.1% [51.0%-75.1%], specificity 82.3% [77.1%-87.5%]).

CONCLUSIONS

Double-blinded evaluation confirmed high assay performance in febrile children. Assay was significantly more accurate than CRP, procalcitonin, and routine laboratory parameters. Additional studies are warranted to support its potential to improve antimicrobial treatment decisions.

Emergency Medicine Evaluation of Community-Acquired Pneumonia: History, Examination, Imaging and Laboratory Assessment, and Risk Scores

BACKGROUND

Pneumonia is a common infection, accounting for approximately one million hospitalizations in the United States annually. This potentially life-threatening disease is commonly diagnosed based on history, physical examination, and chest radiograph.

OBJECTIVE

To investigate emergency medicine evaluation of community-acquired pneumonia including history, physical examination, imaging, and the use of risk scores in patient assessment.

DISCUSSION

Pneumonia is the number one cause of death from infectious disease. The condition is broken into several categories, the most common being community-acquired pneumonia. Diagnosis centers on history, physical examination, and chest radiograph. However, all are unreliable when used alone, and misdiagnosis occurs in up to one-third of patients. Chest radiograph has a sensitivity of 46-77%, and biomarkers including white blood cell count, procalcitonin, and C-reactive protein provide little benefit in diagnosis. Biomarkers may assist admitting teams, but require further study for use in the emergency department. Ultrasound has shown utility in correctly identifying pneumonia. Clinical gestalt demonstrates greater ability to diagnose pneumonia. Clinical scores including Pneumonia Severity Index (PSI); Confusion, blood Urea nitrogen, Respiratory rate, Blood pressure, age 65 score (CURB-65); and several others may be helpful for disposition, but should supplement, not replace, clinical judgment. Patient socioeconomic status must be considered in disposition decisions.

CONCLUSION

The diagnosis of pneumonia requires clinical gestalt using a combination of history and physical examination. Chest radiograph may be negative, particularly in patients presenting early in disease course and elderly patients. Clinical scores can supplement clinical gestalt and assist in disposition when used appropriately.

Clinician-targeted interventions to influence antibiotic prescribing behaviour for acute respiratory infections in primary care: an overview of systematic reviews

BACKGROUND

Antibiotic resistance is a worldwide health threat. Interventions that reduce antibiotic prescribing by clinicians are expected to reduce antibiotic resistance. Disparate interventions to change antibiotic prescribing behaviour for acute respiratory infections (ARIs) have been trialled and meta-analysed, but not yet synthesised in an overview. This overview synthesises evidence from systematic reviews, rather than individual trials.

OBJECTIVES

To systematically review the existing evidence from systematic reviews on the effects of interventions aimed at influencing clinician antibiotic prescribing behaviour for ARIs in primary care.

METHODS

We searched the Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE), MEDLINE, Embase, CINAHL, PsycINFO, and Science Citation Index to June 2016. We also searched the reference lists of all included reviews. We ran a pre-publication search in May 2017 and placed additional studies in 'awaiting classification'.We included both Cochrane and non-Cochrane reviews of randomised controlled trials evaluating the effect of any clinician-focussed intervention on antibiotic prescribing behaviour in primary care. Two overview authors independently extracted data and assessed the methodological quality of included reviews using the ROBIS tool, with disagreements reached by consensus or by discussion with a third overview author. We used the GRADE system to assess the quality of evidence in included reviews. The results are presented as a narrative overview.

MAIN RESULTS

We included eight reviews in this overview: five Cochrane Reviews (33 included trials) and three non-Cochrane reviews (11 included trials). Three reviews (all Cochrane Reviews) scored low risk across all the ROBIS domains in Phase 2 and low risk of bias overall. The remaining five reviews scored high risk on Domain 4 of Phase 2 because the 'Risk of bias' assessment had not been specifically considered and discussed in the review Results and Conclusions. The trials included in the reviews varied in both size and risk of bias. Interventions were compared to usual care.Moderate-quality evidence indicated that C-reactive protein (CRP) point-of-care testing (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.66 to 0.92, 3284 participants, 6 trials), shared decision making (odds ratio (OR) 0.44, 95% CI 0.26 to 0.75, 3274 participants, 3 trials; RR 0.64, 95% CI 0.49 to 0.84, 4623 participants, 2 trials; risk difference -18.44, 95% CI -27.24 to -9.65, 481,807 participants, 4 trials), and procalcitonin-guided management (adjusted OR 0.10, 95% CI 0.07 to 0.14, 1008 participants, 2 trials) probably reduce antibiotic prescribing in general practice. We found moderate-quality evidence that procalcitonin-guided management probably reduces antibiotic prescribing in emergency departments (adjusted OR 0.34, 95% CI 0.28 to 0.43, 2605 participants, 7 trials). The overall effect of these interventions was small (few achieving greater than 50% reduction in antibiotic prescribing, most about a quarter or less), but likely to be clinically important.Compared to usual care, shared decision making probably makes little or no difference to reconsultation for the same illness (RR 0.87, 95% CI 0.74 to 1.03, 1860 participants, 4 trials, moderate-quality evidence), and may make little or no difference to patient satisfaction (RR 0.86, 95% CI 0.57 to 1.30, 1110 participants, 2 trials, low-quality evidence). Similarly, CRP testing probably has little or no effect on patient satisfaction (RR 0.79, 95% CI 0.57 to 1.08, 689 participants, 2 trials, moderate-quality evidence) or reconsultation (RR 1.08, 95% CI 0.93 to 1.27, 5132 participants, 4 trials, moderate-quality evidence). Procalcitonin-guided management probably results in little or no difference in treatment failure in general practice compared to normal care (adjusted OR 0.95, 95% CI 0.73 to 1.24, 1008 participants, 2 trials, moderate-quality evidence), however it probably reduces treatment failure in the emergency department compared to usual care (adjusted OR 0.76, 95% CI 0.61 to 0.95, 2605 participants, 7 trials, moderate-quality evidence).The quality of evidence for interventions focused on clinician educational materials and decision support in reducing antibiotic prescribing in general practice was either low or very low (no pooled result reported) and trial results were highly heterogeneous, therefore we were unable draw conclusions about the effects of these interventions. The use of rapid viral diagnostics in emergency departments may have little or no effect on antibiotic prescribing (RR 0.86, 95% CI 0.61 to 1.22, 891 participants, 3 trials, low-quality evidence) and may result in little to no difference in reconsultation (RR 0.86, 95% CI 0.59 to 1.25, 200 participants, 1 trial, low-quality evidence).None of the trials in the included reviews reported on management costs for the treatment of an ARI or any associated complications.

AUTHORS' CONCLUSIONS

We found evidence that CRP testing, shared decision making, and procalcitonin-guided management reduce antibiotic prescribing for patients with ARIs in primary care. These interventions may therefore reduce overall antibiotic consumption and consequently antibiotic resistance. There do not appear to be negative effects of these interventions on the outcomes of patient satisfaction and reconsultation, although there was limited measurement of these outcomes in the trials. This should be rectified in future trials.We could gather no information about the costs of management, and this along with the paucity of measurements meant that it was difficult to weigh the benefits and costs of implementing these interventions in practice.Most of this research was undertaken in high-income countries, and it may not generalise to other settings. The quality of evidence for the interventions of educational materials and tools for patients and clinicians was either low or very low, which prevented us from drawing any conclusions. High-quality trials are needed to further investigate these interventions.

Sputum bacteriology and clinical response to antibiotics in moderate exacerbation of chronic obstructive pulmonary disease

BACKGROUND

Presence of purulent sputum during an acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is considered sufficient indication for starting empirical antibiotics. We investigated the relationship between detection of potentially pathogenic bacteria (PPB) using sputum culture or polymerase chain reaction (PCR) and clinical response and sought the risk factors for PPB growth.

METHODS

In 342 outpatients with AECOPD, we compared detection rates of H. influenzae (HI) and S. pneumoniae (SP) using conventional sputum culture versus PCR. The utility of either technique to predict clinical cure or failure after effective antibiotics was assessed. The factors predicting positive sputum cultures were evaluated using logistic regression.

RESULTS

Using sputum culture, 132 PPB were detected. The predominant bacteria were HI (40.9%) and SP (19.7%). Detection of HI or SP in sputum was higher using PCR than culture growth (60.8% vs 18.6%; P < .001). Clinical response was not affected by the results of either technique. Independent risk factors for PPB isolation were Gram-negative bacteria on sputum smear (OR 15.78, 95% CI 6.38-39.06; P < .001), sputum purulence (OR 2.31, 95% CI, 1.05-5.11; P = .04), body temperature (OR 0.16, 95% CI 0.05-0.54; P = .003), albumin level (OR 0.29, 95% CI 0.09-0.88; P = .03) and dyspnea grade (OR 0.51, 95% CI 0.27-0.96; P = .04).

CONCLUSIONS

Neither culture growth nor PCR positivity for HI or SP in sputum predicted clinical response to antibiotics; therefore, these tests are not necessary for outpatients with AECOPD. Examining Gram-staining and purulence on sputum smear, however, was significant to predict PPB growth in sputum.

A novel biochemical marker for community-acquired pneumonia: Ischemia-modified albumin

INTRODUCTION

Community-acquired pneumonia (CAP) is a frequent cause of hospitalization and a leading cause of mortality worldwide. Early diagnosis and the initiation of appropriate antibiotic therapy are essential to reduce pneumonia-related morbidity and mortality. CRP is a well-established biomarker in many clinical settings, but has been traditionally considered not specific enough to be a useful guide in the diagnostic process of pneumonia. There is still a need for more specific and practical markers in CAP for diagnosis. The aim of this study was to investigate the diagnostic value of ischemia-modified albumin (IMA) levels in the diagnosis of CAP in the Emergency Department.

METHODS

The study included 81 patients admitted with CAP and 81 control patients. Initial hour levels of IMA and CRP were measured. The IMA mean levels were compared between the study and control group. Correlation analyses were performed to investigate the association of serum IMA levels with CRP.

RESULTS

Mean levels of IMA were 0.532±0.117IU/ml in the study group and 0.345±0.082IU/ml in the control group. IMA levels were significantly higher in the study group compared to the control group. The IMA level of 0.442IU/ml had sensitivity of 75.3% and specificity of 91.3% and was positively correlated with CRP levels (r=0.506; p<0.05).

CONCLUSION

Blood IMA levels significantly increase in adult patients presenting with CAP. IMA may be considered as a novel biomarker in the diagnosis of CAP.

Cost-effectiveness of triage testing for facility-based systematic screening of tuberculosis among Ugandan adults

BACKGROUND

Systematic screening is often proposed as a way to improve case finding for tuberculosis (TB), but the cost-effectiveness of specific strategies for systematic screening remains poorly studied.

METHODS

We constructed a Markov-based decision analytic model to analyse the cost-effectiveness of triage testing for TB in Uganda, compared against passive case detection with Xpert MTB/RIF. We assumed a triage algorithm whereby all adults presenting to healthcare centres would be screened for cough, and those with cough of at least 2 weeks would receive the triage test, with positive triage results confirmed by Xpert MTB/RIF. We adopted the perspective of the TB control sector, using a primary outcome of the cost per year of life gained (YLG) over a lifetime time horizon.

RESULTS

Systematic screening in a population with a 5% underlying prevalence of TB was estimated to cost US$610 per YLG (95% uncertainty range US$200-US$1859) with chest X-ray (CXR) (US$5 per test, specificity 0.67), or US$588 (US$221-US$1746) with C reactive protein (CRP) (US$3 per test, specificity 0.59). In addition to the cost and specificity of the triage test, cost-effectiveness was most sensitive to the underlying prevalence of TB, monthly risk of mortality in people with untreated TB and the proportion of patients with TB who would be treated in the absence of systematic screening.

CONCLUSIONS

To optimise the cost-effectiveness of facility-based systematic screening of TB with a triage test, it must be carried out in a high-risk population, or use triage tests that are cheaper or more specific than CXR or CRP.

The added value of C-reactive protein measurement in diagnosing pneumonia in primary care: a meta-analysis of individual patient data

BACKGROUND

C-reactive protein (CRP) is increasingly being included in the diagnostic work-up for community-acquired pneumonia in primary care. Its added diagnostic value beyond signs and symptoms, however, remains unclear. We conducted a meta-analysis of individual patient data to quantify the added value of CRP measurement.

METHODS

We included studies of the diagnostic accuracy of CRP in adult outpatients with suspected lower respiratory tract infection. We contacted authors of eligible studies for inclusion of data and for additional data as needed. The value of adding CRP measurement to a basic signs-and-symptoms prediction model was assessed. Outcome measures were improvement in discrimination between patients with and without pneumonia in primary care and improvement in risk classification, both within the individual studies and across studies.

RESULTS

Authors of 8 eligible studies (n = 5308) provided their data sets. In all of the data sets, discrimination between patients with and without pneumonia improved after CRP measurement was added to the prediction model (extended model), with a mean improvement in the area under the curve of 0.075 (range 0.02-0.18). In a hypothetical cohort of 1000 patients, the proportion of patients without pneumonia correctly classified at low risk increased from 28% to 36% in the extended model, and the proportion with pneumonia correctly classified at high risk increased from 63% to 70%. The number of patients with pneumonia classified at low risk did not change (n = 4). Overall, the proportion of patients assigned to the intermediate-risk category decreased from 56% to 51%.

INTERPRETATION

Adding CRP measurement to the diagnostic work-up for suspected pneumonia in primary care improved the discrimination and risk classification of patients. However, it still left a substantial group of patients classified at intermediate risk, in which clinical decision-making remains challenging.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

Background

In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics.

Methods

Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers.

Findings

Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections.

Discussion

This manuscript provides a summary of host biomarkers to differentiate bacterial from non-bacterial infections in patients with acute febrile illness. Findings provide a basis for prioritizing efforts for further research, assay development and eventual commercialization of rapid point-of-care tests to guide use of antimicrobials. This review also highlights gaps in current knowledge that should be addressed to further improve management of febrile patients.

Out-of-hours antibiotic prescription after screening with C reactive protein: a randomised controlled study

OBJECTIVE

To evaluate the effect of preconsultation C reactive protein (CRP) screening on antibiotic prescribing and referral to hospital in Norwegian primary care settings with low prevalence of serious infections.

DESIGN

Randomised controlled observational study at out-of-hours services in Norway.

SETTING

Primary care.

PARTICIPANTS

401 children (0-6 years) with fever and/or respiratory symptoms were recruited from 5 different out-of-hours services (including 1 paediatric emergency clinic) in 2013-2015.

INTERVENTION

Data were collected from questionnaires and clinical examination results. Every third child was randomised to a CRP test before the consultation; for the rest, the doctor ordered a CRP test if considered necessary.

OUTCOME MEASURES

Main outcome variables were prescription of antibiotics and referral to hospital.

RESULTS

In the group pretested with CRP, the antibiotic prescription rate was 26%, compared with 22% in the control group. In the group pretested with CRP, 5% were admitted to hospital, compared with 9% in the control group. These differences were not statistically significant. The main predictors for ordering a CRP test were parents' assessment of seriousness of the illness and the child's temperature. Paediatricians ordered CRP tests less frequently than did other doctors (9% vs 56%, p<0.001).

CONCLUSIONS

Preconsultation screening with CRP of children presenting to out-of-hours services with fever and/or respiratory symptoms does not significantly affect the prescription of antibiotics or referral to hospital.

TRIAL REGISTRATION NUMBER

NCT02496559; Results.

'I'm fishing really'--inflammatory marker testing in primary care: a qualitative study

Background

Inflammatory markers can be helpful as part of the diagnostic workup for specific diseases or for monitoring disease activity. A third use is as a screening and/or triage tool to differentiate between the presence or absence of disease. Most research into inflammatory markers looks at diagnosis of specific diseases and comes from secondary care. Qualitative studies to explore when and why clinicians use these tests in primary care are lacking.

Aim

To identify clinicians’ approaches to inflammatory marker testing in primary care.

Design and setting

Qualitative study with 26 GPs and nurse practitioners.

Method

Interviews were conducted using a semi-structured topic guide. Clinicians reviewed recent cases of inflammatory marker testing in their pathology inbox. Interviews were audiorecorded and transcribed. Qualitative analysis was conducted by two of the authors.

Results

Clinicians are uncertain about the appropriate use of inflammatory markers and differ in their approach to testing patients with undifferentiated symptoms. Normal or significantly elevated inflammatory markers are seen as helpful, but mildly raised inflammatory markers in the context of non-specific symptoms are difficult to interpret. Clinicians describe a tension between not wanting to ‘miss anything’ and, on the other hand, being wary of picking up borderline abnormalities that can lead to cascades of further tests. Diagnostic uncertainty is a common reason for inflammatory marker testing, with the aim to reassure; however, paradoxically, inconclusive results can generate a cycle of uncertainty and anxiety.

Conclusion

Further research is needed to define when inflammatory marker testing is useful in primary care and how to interpret results.

Community-acquired pneumonia in primary care: clinical assessment and the usability of chest radiography

OBJECTIVES

To investigate the diagnostic value of different clinical and laboratory findings in pneumonia and to explore the association between the doctor's degree of suspicion and chest X-ray (CXR) result and to evaluate whether or not CXR should be used routinely in primary care, when available.

DESIGN

A three-year prospective study was conducted between September 2011 and December 2014.

SETTING

Two primary care settings in Linköping, Sweden.

SUBJECTS

A total of 103 adult patients with suspected pneumonia in primary care.

MAIN OUTCOME MEASURES

The physicians recorded results of a standardized medical physical examination, including laboratory results, and rated their suspicion into three degrees. The outcome of the diagnostic variables and the degree of suspicion was compared with the result of CXR.

RESULTS

Radiographic pneumonia was reported in 45% of patients. When the physicians were sure of the diagnosis radiographic pneumonia was found in 88% of cases (p < 0.001), when quite sure the frequency of positive CXR was 45%, and when not sure 28%. Elevated levels of C-reactive protein (CRP) ≥ 50mg/L were associated with the presence of radiographic pneumonia when the diagnosis was suspected (p < 0.001).

CONCLUSION

This study indicates that CXR can be useful if the physician is not sure of the diagnosis, but when sure one can rely on one's judgement without ordering CXR.

KEY POINTS

There are different guidelines but no consensus on how to manage community-acquired pneumonia in primary care. When the physician is sure of the diagnosis the judgement is reliable without chest X-ray and antibiotics can be safely prescribed. Chest X-ray can be useful in the assessment of pneumonia in primary care, when the physician is not sure of the diagnosis.

What a difference a CRP makes. A prospective observational study on how point-of-care C-reactive protein testing influences antibiotic prescription for respiratory tract infections in Swedish primary health care

OBJECTIVE

To explore how C-reactive protein (CRP) tests serve to support physicians in decisions concerning antibiotic prescription to patients with respiratory tract infections (RTI).

DESIGN

Prospective observational study.

SETTING

Primary health care centres in western Sweden.

SUBJECTS

Physicians in primary health care. Patients with acute RTI.

MAIN OUTCOME MEASURES

Physician willingness to measure CRP, their ability to estimate CRP, and changes in decision-making concerning antibiotic treatment based on error estimate and the physician's opinion of whether CRP measurement was crucial.

RESULTS

Data from 340 consultations were gathered. CRP testing was found to be crucial in 130 cases. In 86% of visits decisions regarding antibiotic prescription were unchanged. Physicians considering CRP crucial and physicians making an error estimate of CRP altered their decisions concerning antibiotic prescription after CRP testing more often than those who considered CRP unnecessary, and those making a more accurate estimate. Physicians changed their decision on antibiotic prescription in 49 cases. In the majority of these 49 cases physicians underestimated CRP levels, and the majority of changes were from "no" to "yes" as to whether to prescribe antibiotics.

CONCLUSION

CRP is an important factor in the decision on whether to prescribe antibiotics for RTIs. Error estimates of CRP and willingness to measure CRP are important factors leading to physicians changing decisions on antibiotic treatment. Key points There is a generally low antibiotic prescription rate and a high frequency of C-reactive protein (CRP) testing for respiratory tract infections (RTIs) in Sweden. CRP testing was considered essential to further management in 38% of cases. In 86% of visits decisions concerning antibiotic prescription were unchanged. The strongest predictors for revised decisions on antibiotic treatment were error estimates of CRP and the physician's opinion that CRP measurement was crucial.

Acute Phase Reactants in Infections: Evidence-Based Review and a Guide for Clinicians

There is increasing evidence to support the role of various acute phase reactants as an adjunct to clinical judgement in the management of various infections. Procalcitonin is more specific in diagnosing bacterial infections and has a wider role in the management of complex infections. Procalcitonin based antibiotic guidance is helpful in antibiotic management in patients with pneumonia and sepsis

Acute-phase reactants such as erythrocyte sedimentation rate and C-reactive protein have traditionally been used as markers for inflammation and as a measure of “sickness index” in infectious and noninfectious conditions. In the last decade, more data have become available on the wider and more specific role for these markers in the management of complex infections. This includes the potential role in early diagnosis, in differentiating infectious from noninfectious causes, as a prognostic marker, and in antibiotic guidance strategies. A better defined role for biological markers as a supplement to clinical assessment may lead to more judicious antibiotic prescriptions, and it has the potential for a long-term favorable impact on antimicrobial stewardship and antibiotic resistance. Procalcitonin as a biological marker has been of particular interest in this regard. This review examines the current published evidence and summarizes the role of various acute-phase markers in infections. A MEDLINE search of English-language articles on acute-phase reactants and infections published between 1986 and March 2015 was conducted. Additional articles were also identified through a search of references from the retrieved articles, published guidelines, systematic reviews, and meta-analyses.

A novel host-proteome signature for distinguishing between acute bacterial and viral infections

Bacterial and viral infections are often clinically indistinguishable, leading to inappropriate patient management and antibiotic misuse. Bacterial-induced host proteins such as procalcitonin, C-reactive protein (CRP), and Interleukin-6, are routinely used to support diagnosis of infection. However, their performance is negatively affected by inter-patient variability, including time from symptom onset, clinical syndrome, and pathogens. Our aim was to identify novel viral-induced host proteins that can complement bacterial-induced proteins to increase diagnostic accuracy. Initially, we conducted a bioinformatic screen to identify putative circulating host immune response proteins. The resulting 600 candidates were then quantitatively screened for diagnostic potential using blood samples from 1002 prospectively recruited patients with suspected acute infectious disease and controls with no apparent infection. For each patient, three independent physicians assigned a diagnosis based on comprehensive clinical and laboratory investigation including PCR for 21 pathogens yielding 319 bacterial, 334 viral, 112 control and 98 indeterminate diagnoses; 139 patients were excluded based on predetermined criteria. The best performing host-protein was TNF-related apoptosis-inducing ligand (TRAIL) (area under the curve [AUC] of 0.89; 95% confidence interval [CI], 0.86 to 0.91), which was consistently up-regulated in viral infected patients. We further developed a multi-protein signature using logistic-regression on half of the patients and validated it on the remaining half. The signature with the highest precision included both viral- and bacterial-induced proteins: TRAIL, Interferon gamma-induced protein-10, and CRP (AUC of 0.94; 95% CI, 0.92 to 0.96). The signature was superior to any of the individual proteins (P<0.001), as well as routinely used clinical parameters and their combinations (P<0.001). It remained robust across different physiological systems, times from symptom onset, and pathogens (AUCs 0.87-1.0). The accurate differential diagnosis provided by this novel combination of viral- and bacterial-induced proteins has the potential to improve management of patients with acute infections and reduce antibiotic misuse.

Clinical and haematological predictors of antibiotic prescribing for acute cough in adults in Swiss practices--an observational study

Background

Acute cough is a common problem in general practice and is often caused by a self-limiting, viral infection. Nonetheless, antibiotics are often prescribed in this situation, which may lead to unnecessary side effects and, even worse, the development of antibiotic resistant microorganisms worldwide. This study assessed the role of point-of-care C-reactive protein (CRP) testing and other predictors of antibiotic prescription in patients who present with acute cough in general practice.

Methods

Patient characteristics, symptoms, signs, and laboratory and X-ray findings from 348 patients presenting to 39 general practitioners with acute cough, as well as the GPs themselves, were recorded by fourth-year medical students during their three-week clerkships in general practice. Patient and clinician characteristics of those prescribed and not-prescribed antibiotics were compared using a mixed-effects model.

Results

Of 315 patients included in the study, 22% were prescribed antibiotics. The two groups of patients, those prescribed antibiotics and those treated symptomatically, differed significantly in age, demand for antibiotics, days of cough, rhinitis, lung auscultation, haemoglobin level, white blood cell count, CRP level and the GP’s license to self-dispense antibiotics. After regression analysis, only the CRP level, the white blood cell count and the duration of the symptoms were statistically significant predictors of antibiotic prescription.

Conclusions

The antibiotic prescription rate of 22% in adult patients with acute cough in the Swiss primary care setting is low compared to other countries. GPs appear to use point-of-care CRP testing in addition to the duration of clinical symptoms to help them decide whether or not to prescribe antibiotics.

Biomarkers as point-of-care tests to guide prescription of antibiotics in patients with acute respiratory infections in primary care

Background Acute respiratory infections (ARIs) are by far the most common reason for prescribing an antibiotic in primary care, even though the majority of ARIs are of viral or non-severe bacterial aetiology. Unnecessary antibiotic use will, in many cases, not be beneficial to the patients' recovery and expose them to potential side effects. Furthermore, as a causal link exists between antibiotic use and antibiotic resistance, reducing unnecessary antibiotic use is a key factor in controlling this important problem. Antibiotic resistance puts increasing burdens on healthcare services and renders patients at risk of future ineffective treatments, in turn increasing morbidity and mortality from infectious diseases. One strategy aiming to reduce antibiotic use in primary care is the guidance of antibiotic treatment by use of a point-of-care biomarker. A point-of-care biomarker of infection forms part of the acute phase response to acute tissue injury regardless of the aetiology (infection, trauma and inflammation) and may in the correct clinical context be used as a surrogate marker of infection,possibly assisting the doctor in the clinical management of ARIs.Objectives To assess the benefits and harms of point-of-care biomarker tests of infection to guide antibiotic treatment in patients presenting with symptoms of acute respiratory infections in primary care settings regardless of age.Search methods We searched CENTRAL (2013, Issue 12), MEDLINE (1946 to January 2014), EMBASE (2010 to January 2014), CINAHL (1981 to January 2014), Web of Science (1955 to January 2014) and LILACS (1982 to January 2014).Selection criteria We included randomised controlled trials (RCTs) in primary care patients with ARIs that compared use of point-of-care biomarkers with standard of care. We included trials that randomised individual patients as well as trials that randomised clusters of patients(cluster-RCTs).Two review authors independently extracted data on the following outcomes: i) impact on antibiotic use; ii) duration of and recovery from infection; iii) complications including the number of re-consultations, hospitalisations and mortality; iv) patient satisfaction. We assessed the risk of bias of all included trials and applied GRADE. We used random-effects meta-analyses when feasible. We further analysed results with a high level of heterogeneity in pre-specified subgroups of individually and cluster-RCTs.Main results The only point-of-care biomarker of infection currently available to primary care identified in this review was C-reactive protein. We included six trials (3284 participants; 139 children) that evaluated a C-reactive protein point-of-care test. The available information was from trials with a low to moderate risk of bias that address the main objectives of this review.Overall a reduction in the use of antibiotic treatments was found in the C-reactive protein group (631/1685) versus standard of care(785/1599). However, the high level of heterogeneity and the statistically significant test for subgroup differences between the three RCTs and three cluster-RCTs suggest that the results of the meta-analysis on antibiotic use should be interpreted with caution and the pooled effect estimate (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.66 to 0.92; I2 statistic = 68%) may not be meaningful.The observed heterogeneity disappeared in our pre planned subgroup analysis based on study design: RR 0.90, 95% CI 0.80 to 1.02; I2 statistic = 5% for RCTs and RR 0.68, 95% CI 0.61 to 0.75; I2 statistic = 0% for cluster-RCTs, suggesting that this was the cause of the observed heterogeneity.There was no difference between using a C-reactive protein point-of-care test and standard care in clinical recovery (defined as at least substantial improvement at day 7 and 28 or need for re-consultations day 28). However, we noted an increase in hospitalisations in the C-reactive protein group in one study, but this was based on few events and may be a chance finding. No deaths were reported in any of the included studies.We classified the quality of the evidence as moderate according to GRADE due to imprecision of the main effect estimate.Authors' conclusions A point-of-care biomarker (e.g. C-reactive protein) to guide antibiotic treatment of ARIs in primary care can reduce antibiotic use,although the degree of reduction remains uncertain. Used as an adjunct to a doctor's clinical examination this reduction in antibiotic use did not affect patient-reported outcomes, including recovery from and duration of illness.However, a possible increase in hospitalisations is of concern. A more precise effect estimate is needed to assess the costs of the intervention and compare the use of a point-of-care biomarker to other antibiotic-saving strategies.

Is C-reactive protein testing useful to predict outcome in patients with acute bronchitis?

BACKGROUND

A recent clinical trial could not find differences between anti-inflammatory drugs, antibiotics and placebo in shortening the duration of symptoms in acute bronchitis.

OBJECTIVES

To investigate if C-reactive protein (CRP) concentrations at presentation are predictive of symptom resolution in these patients.

METHODS

We performed a secondary analysis of the data from a placebo-controlled, randomized clinical trial carried out in primary care. Patients from 18 to 70 years of age presenting a respiratory tract infection of <1 week of evolution, with cough as the predominant symptom and the presence of discoloured expectoration, were enrolled in the study. On the baseline visit, CRP was determined in capillary blood and a five-item symptom diary was given. Patients were followed up to 30 days. The main outcome measure was the number of days with persistent cough.

RESULTS

A total of 312 subjects fulfilled all the criteria for the efficacy analysis and had undergone the CRP test; of these, 56.4% presented a CRP value <8 mg/l and 76% presented <20 mg/l. There were no significant differences in the median duration of cough: 10 days among patients with CRP concentrations <8 mg/l [95% confidence interval (CI): 8-11 days], 11 days among those with concentrations ranging from 8 to 19 mg/l (95% CI: 8-16) and 11 days in those with CRP >20 mg/l (95% CI: 9-12) (P = 0.337).

CONCLUSION

Among patients with uncomplicated acute bronchitis and discoloured sputum, the CRP concentrations at presentation are not helpful for predicting symptom resolution.

Diagnostic accuracy and clinical role of rapid C-reactive protein testing in HIV-infected individuals with presumed tuberculosis in South Africa

OBJECTIVE

To determine the accuracy and role of rapid C-reactive protein (CRP) testing in human immunodeficiency virus (HIV) infected individuals with presumed tuberculosis (TB).

DESIGN

We enrolled HIV-infected adults (≥18 years)with a cough of ≥2 weeks and negative sputum smears for acid-fast bacilli in KwaZulu-Natal, South Africa. Participants were evaluated for pulmonary TB (PTB) by a nurse with rapid CRP, and independently by a physician by chest radiograph. Rapid CRP test results were compared with laboratory CRP and sputum sent for confirmation of TB.

RESULTS

Among 93 participants, 55 (59%) were female, the mean age was 35 years, and the median CD4 count was 177/mm3. Forty-five (54%) participants were diagnosed with PTB. Diagnostic sensitivity and specificity were respectively 95% (95%CI 74–99) and 51%(95%CI 35–66) for rapid CRP >8 mg/l, 87% (95%CI 73–96) and 53% (95%CI 38–68) for nurse assessment, and 69% (95%CI 52–83) and 76% (95%CI 61–87) for physician examination. Combining a negative rapid CRP(≤8 mg/l) with nurse and physician assessments reduced the post-test probability of PTB from 22% to 6% and from 32% to 6%, respectively.

CONCLUSION

Rapid CRP testing helped exclude PTB,and may be a valuable test in assisting nurses and physicians in TB-endemic regions.

Inflammatory response in mixed viral-bacterial community-acquired pneumonia

Background

The role of mixed pneumonia (virus + bacteria) in community-acquired pneumonia (CAP) has been described in recent years. However, it is not known whether the systemic inflammatory profile is different compared to monomicrobial CAP. We wanted to investigate this profile of mixed viral-bacterial infection and to compare it to monomicrobial bacterial or viral CAP.

Methods

We measured baseline serum procalcitonin (PCT), C reactive protein (CRP), and white blood cell (WBC) count in 171 patients with CAP with definite etiology admitted to a tertiary hospital: 59 (34.5%) bacterial, 66 (39.%) viral and 46 (27%) mixed (viral-bacterial).

Results

Serum PCT levels were higher in mixed and bacterial CAP compared to viral CAP. CRP levels were higher in mixed CAP compared to the other groups. CRP was independently associated with mixed CAP. CRP levels below 26 mg/dL were indicative of an etiology other than mixed in 83% of cases, but the positive predictive value was 45%. PCT levels over 2.10 ng/mL had a positive predictive value for bacterial-involved CAP versus viral CAP of 78%, but the negative predictive value was 48%.

Conclusions

Mixed CAP has a different inflammatory pattern compared to bacterial or viral CAP. High CRP levels may be useful for clinicians to suspect mixed CAP.

Association between point-of-care CRP testing and antibiotic prescribing in respiratory tract infections: a systematic review and meta-analysis of primary care studies

BACKGROUND

Most patients with respiratory tract infections (RTIs) are prescribed antibiotics in general practice. However, there is little evidence that antibiotics bring any value to the treatment of most RTIs. Point-of-care C-reactive protein testing may reduce antibiotic prescribing.

AIM

To systematically review studies that have examined the association between point-of-care (POC) C-reactive protein testing and antibiotic prescribing for RTIs in general practice.

DESIGN AND SETTING

Systematic review and meta-analysis of randomised controlled trials and observational studies.

METHOD

MEDLINE(®) and Embase were systematically searched to identify relevant publications. All studies that examined the association between POC C-reactive protein testing and antibiotic prescribing for patients with RTIs were included. Two authors independently screened the search results and extracted data from eligible studies. Dichotomous measures of outcomes were combined using risk ratios (RRs) with 95% confidence intervals (CIs) either by fixed or random-effect models.

RESULTS

Thirteen studies containing 10 005 patients met the inclusion criteria. POC C-reactive protein testing was associated with a significant reduction in antibiotic prescribing at the index consultation (RR 0.75, 95% CI = 0.67 to 0.83), but was not associated with antibiotic prescribing at any time during the 28-day follow-up period (RR 0.85, 95% CI = 0.70 to 1.01) or with patient satisfaction (RR 1.07, 95% CI = 0.98 to 1.17).

CONCLUSION

POC C-reactive protein testing significantly reduced antibiotic prescribing at the index consultation for patients with RTIs. Further studies are needed to analyse the confounders that lead to the heterogeneity.

Usefulness of C-reactive protein testing in acute cough/respiratory tract infection: an open cluster-randomized clinical trial with C-reactive protein testing in the intervention group

Background

Point of care testing for C-reactive protein (CRP) has shown promise as a measure to reduce unnecessary antibiotic prescribing in respiratory tract infections (RTI), but its use in primary care is still controversial. We aimed to evaluate the effect of CRP testing on the prescription of antibiotics, referral for radiography, and the outcome of patients in general practice with acute cough/RTI.

Methods

An open-cluster randomized clinical trial was conducted, with CRP testing performed in the intervention group. Antibiotic prescribing and referral for radiography were the main outcome measures.

Results

A total of 179 patients were included: 101 in the intervention group and 78 in the control group. The two groups were similar in clinical characteristics. In the intervention group, the antibiotic prescribing rate was 37.6%, which was significantly lower than that in the control group (58.9%) (P = 0.006). Referral for chest X-ray was also significantly lower in the intervention group (55.4%) than in the control group (75.6%) (P = 0.004). The recovery rate, as recorded by the GPs, was 92.9% and 93.6% in the intervention and control groups, respectively.

Conclusion

The study showed that CRP testing in patients with acute cough/RTI may reduce antibiotic prescribing and referral for radiography, probably without compromising recovery.

Trial registration

The trial was registered in the ClinicalTrials.gov Protocol Registration System (identification number: NCT01794819).

Diagnostic and prognostic value of serum C-reactive protein for screening for HIV-associated tuberculosis

BACKGROUND

Rapid means of ruling in or ruling out tuberculosis (TB) would permit more efficient management of patients starting antiretroviral treatment (ART).

OBJECTIVE

To assess the diagnostic and prognostic utility of C-reactive protein (CRP) among patients being screened for TB before ART in a South African ART clinic.

DESIGN

Patients were microbiologically screened for TB regardless of symptoms; serum CRP was measured, and mortality at 3 months was assessed.

RESULTS

Among 496 patients (median CD4 count 171 cells/l), culture-positive TB was diagnosed in 81 (16.3%). CRP concentrations were much higher among TB cases (median 57.8 mg/l, IQR 20.0202.7) than in those without TB (6.4 mg/l, IQR 2.121.8, P < 0.001). Very low (<1.5 mg/l) CRP concentrations excluded TB (100% negative predictive value), whereas very high concentrations (>400 mg/l) were strongly predictive of TB (100% positive predictive value). However, these thresholds encompassed only 14.3% and 2.0%, respectively, of all patients screened and identified only 12.3% of TB cases. CRP concentrations ≥50 mg/l were associated with poor prognostic characteristics, higher mycobacterial load, disseminated disease and greater mortality risk.

CONCLUSION

CRP concentrations identified groups of patients with very high or very low TB risk, but only in an unacceptably small minority of patients screened. However, in those with confirmed TB, CRP concentrations had useful prognostic value.

Use of serum C reactive protein and procalcitonin concentrations in addition to symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough: diagnostic study

OBJECTIVES

To quantify the diagnostic accuracy of selected inflammatory markers in addition to symptoms and signs for predicting pneumonia and to derive a diagnostic tool.

DESIGN

Diagnostic study performed between 2007 and 2010. Participants had their history taken, underwent physical examination and measurement of C reactive protein (CRP) and procalcitonin in venous blood on the day they first consulted, and underwent chest radiography within seven days.

SETTING

Primary care centres in 12 European countries.

PARTICIPANTS

Adults presenting with acute cough.

MAIN OUTCOME MEASURES

Pneumonia as determined by radiologists, who were blind to all other information when they judged chest radiographs.

RESULTS

Of 3106 eligible patients, 286 were excluded because of missing or inadequate chest radiographs, leaving 2820 patients (mean age 50, 40% men) of whom 140 (5%) had pneumonia. Re-assessment of a subset of 1675 chest radiographs showed agreement in 94% (κ 0.45, 95% confidence interval 0.36 to 0.54). Six published "symptoms and signs models" varied in their discrimination (area under receiver operating characteristics curve (ROC) ranged from 0.55 (95% confidence interval 0.50 to 0.61) to 0.71 (0.66 to 0.76)). The optimal combination of clinical prediction items derived from our patients included absence of runny nose and presence of breathlessness, crackles and diminished breath sounds on auscultation, tachycardia, and fever, with an ROC area of 0.70 (0.65 to 0.75). Addition of CRP at the optimal cut off of >30 mg/L increased the ROC area to 0.77 (0.73 to 0.81) and improved the diagnostic classification (net reclassification improvement 28%). In the 1556 patients classified according to symptoms, signs, and CRP >30 mg/L as "low risk" (<2.5%) for pneumonia, the prevalence of pneumonia was 2%. In the 132 patients classified as "high risk" (>20%), the prevalence of pneumonia was 31%. The positive likelihood ratio of low, intermediate, and high risk for pneumonia was 0.4, 1.2, and 8.6 respectively. Measurement of procalcitonin added no relevant additional diagnostic information. A simplified diagnostic score based on symptoms, signs, and CRP >30 mg/L resulted in proportions of pneumonia of 0.7%, 3.8%, and 18.2% in the low, intermediate, and high risk group respectively.

CONCLUSIONS

A clinical rule based on symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough performed best in patients with mild or severe clinical presentation. Addition of CRP concentration at the optimal cut off of >30 mg/L improved diagnostic information, but measurement of procalcitonin concentration did not add clinically relevant information in this group.