Analytical performance, agreement and user-friendliness of five C-reactive protein point-of-care tests

Analytical performance and user-friendliness of four commercially available point-of-care devices for C-reactive protein

INTRODUCTION

Proper implementation of Point-of-Care testing (POCT) for C-reactive protein (CRP) in primary care can decrease the inappropriate use of antibiotics, thereby tackling the problem of growing antimicrobial resistance.

OBJECTIVE

The analytical performance and user-friendliness of four POCT-CRP assays were evaluated: QuikRead go easy, LumiraDx, cobas b 101 and Afinion 2.

MATERIALS AND METHODS

Imprecision was evaluated using plasma pools in addition to manufacturer-specific control material. Trueness was assessed by verification of traceability to ERM-DA474/IFCC in parallel to method comparison towards the central laboratory CRP method (cobas c 503) using i) retrospectively selected plasma samples (n = 100) and ii) prospectively collected capillary whole blood samples (n = 50). User-friendliness was examined using a questionnaire.

RESULTS

Between-day imprecision on plasma pools varied from 4.5 % (LumiraDx) to 11.5 % (QuikRead). Traceability verification revealed no significant difference between cobas c 503 CRP results and the ERM-DA474/IFCC certified value. cobas b 101 and Afinion achieved the best agreement with the central laboratory method. LumiraDx and QuikRead revealed a negative mean difference, with LumiraDx violating the criterion of > 95 % of POCT-CRP-results within ± 20 % of the comparison method. Regarding user-friendliness, Afinion obtained the highest Likert-scores.

CONCLUSION

The analytical performance and user-friendliness of POCT-CRP devices varies among manufacturers, emphasizing the need for quality assurance supervised by a central laboratory.

Comparison of commercially available, rapid, point-of-care C-reactive protein assays among children with febrile illness in southwestern Uganda

In Uganda, children with febrile illness are often treated with antibiotics even though most have self-limiting, likely viral, infections. C-reactive protein (CRP) measurement can help identify those who are more likely to have a bacterial infection and therefore need antibiotic treatment. Implementation of a CRP rapid diagnostic test (RDT) at the point-of-care in resource-constrained settings with minimal laboratory infrastructure could reduce unnecessary antibiotic use. In this study, we evaluated the performance of three semi-quantitative CRP RDTs (Actim, BTNX, Duo) against a reference CRP assay requiring an electrically powered analyzer (Afinion). While both tests demonstrated substantial agreement with Afinion, Actim had slightly higher agreement than BTNX. The sensitivity was higher for the BTNX test, whereas the Actim test had a higher specificity, at cut-offs of 40 mg/L and 80 mg/L. At a cut-off of 20 mg/L, Duo demonstrated substantial agreement with the Afinion test as well. Our results demonstrate the reliability of CRP RDTs when compared to a reference standard. CRP RDTs without the need for a laboratory-based analyzer are promising tools for optimizing antibiotic use in low-resource settings.

Patient Stratification for Antibiotic Prescriptions Based on the Bound-Free Phase Detection Immunoassay of C-Reactive Protein in Serum Samples

C-reactive protein is a well-studied host response biomarker, whose diagnostic performance depends on its accurate classification into concentration zones defined by clinical scenario-specific cutoff values. We validated a newly developed, bead-based, bound-free phase detection immunoassay (BFPD-IA) versus a commercial CE-IVD enzyme-linked immunosorbent assay (ELISA) kit and a commercial CE-IVD immunoturbidimetric assay (ITA) kit. The latter was performed on a fully automated DPC Konelab 60i clinical analyzer used in routine diagnosis. We classified 53 samples into concentration zones derived from four different sets of cutoff values that are related to antibiotic prescription scenarios in the case of respiratory tract infections. The agreements between the methods were ELISA/ITA at 87.7%, ELISA/BFPD-IA at 87.3%, and ITA/-BFPD-IA at 93.9%, reaching 98-99% in all cases when considering the calculated relative combined uncertainty of the single measurement of each sample. In a subgroup of 37 samples, which were analyzed for absolute concentration quantification, the scatter plot slopes' correlations were as follows: ELISA/ITA 1.15, R2 = 0.97; BFPD-IA/ELISA 1.12, R2 = 0.95; BFPD-IA/ITA 0.95, R2 = 0.93. These very good performances and the agreement between BFPD-IA and ITA (routine diagnostic), combined with BFPD-IA's functional advantages over ITA (and ELISA)-such as quick time to result (~20 min), reduced consumed reagents (only one assay buffer and no washing), few and easy steps, and compatibility with nucleic-acid-amplification instruments-render it a potential approach for a reliable, cost-efficient, evidence-based point-of-care diagnostic test for guiding antibiotic prescriptions.

Analytical performance of 17 commercially available point-of-care tests for CRP to support patient management at lower levels of the health system

Accurate and precise point-of-care (POC) testing for C-reactive protein (CRP) can help support healthcare providers in the clinical management of patients. Here, we compared the analytical performance of 17 commercially available POC CRP tests to enable more decentralized use of the tool. The following CRP tests were evaluated. Eight quantitative tests: QuikRead go (Aidian), INCLIX (Sugentech), Spinit (Biosurfit), LS4000 (Lansionbio), GS 1200 (Gensure Biotech), Standard F200 (SD Biosensor), Epithod 616 (DxGen), IFP-3000 (Xincheng Biological); and nine semi-quantitative tests: Actim CRP (ACTIM), NADAL Dipstick (nal von minden), NADAL cassette (nal von minden), ALLTEST Dipstick (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10-40-80 (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10-30 (Hangzhou Alltest Biotech), Biotest (Hangzhou Biotest Biotech), BTNX Quad Line (BTNX), BTNX Tri Line (BTNX). Stored samples (n = 660) had previously been tested for CRP using Cobas 8000 Modular analyzer (Roche Diagnostics International AG, Rotkreuz, Switzerland (reference standards). CRP values represented the clinically relevant range (10-100 mg/L) and were grouped into four categories (<10 mg/L, 10-40 mg/L or 10-30 mg/L, 40-80 mg/L or 30-80 mg/L, and > 80mg/L) for majority of the semi-quantitative tests. Among the eight quantitative POC tests evaluated, QuikRead go and Spinit exhibited better agreement with the reference method, showing slopes of 0.963 and 0.921, respectively. Semi-quantitative tests with the four categories showed a poor percentage agreement for the intermediate categories and higher percentage agreement for the lower and upper limit categories. Analytical performance varied considerably for the semi-quantitative tests, especially among the different categories of CRP values. Our findings suggest that quantitative tests might represent the best choice for a variety of use cases, as they can be used across a broad range of CRP categories.

Could combined rapid diagnostic testing for malaria and c-reactive protein be helpful for the diagnosis and management of febrile illnesses in children under-5 years of age in rural Burkina Faso?

BACKGROUND

Febrile illnesses are among the most important reasons for medical consultation in sub-Saharan Africa and are frequently treated with antimicrobials due to the unavailability of appropriate diagnostic tools. This practice leads to antimicrobial resistance, with increasing mortality and morbidity as result. One of the few accessible diagnostic tools available in low resource settings is malaria rapid diagnostic tests (mRDTs) which contributed to reducing the over-prescription of anti-malarials, but cannot guide antibiotic prescriptions. To circumvent this problem, we explored whether combined testing with mRDT and c-reactive protein (CRP) could improve the diagnosis of febrile illnesses and subsequent prescription of antibiotics.

METHODS

Clinical specimens (blood, stool and urine) collected from 396 febrile children (axillary temperature of ≥ 37.5 °C) were analyzed with rapid diagnostic tests (malaria and CRP) and microbiology culture to establish the possible cause of fever. Actual antimicrobial prescriptions given to the children were compared with those that could be given based on combined CRP-malaria testing.

RESULTS

In total, 68.7% (272/396) of malaria cases were diagnosed by mRDT-Pf-HRP-2. CRP test was positive in 84.3% (334/396) of the children, but bacterial infections were confirmed in 12.4% (49/396) of them. A possible cause of fever could not be established in 20.5% (81/396) of cases. Based on the diagnostic practice in place, 265 of the children with a positive mRDT-Pf-HRP-2 received anti-malarial treatment. Furthermore, 89.5% (111/124) of negative mRDT results received antibiotic treatment and 37.1% (46/124) received antimalarial treatment. Of these 124 cases, 80 had positive CRP tests and 44 negative CRP tests. If the results of CRP testing are considered, 44 CRP/mRDT negative children would not get antibiotic treatment, resulting in a 35.5% reduction in antibiotic prescriptions. However, 2 cases with a bacterial infection would be denied appropriate treatment.

CONCLUSION

Combining mRDT-PfHRP2 with CRP testing is particularly useful in children for whom both tests are negative as it results in a reduction of antibiotics prescriptions. However, there is a risk to miss potential severe bacterial infections and a close follow-up of these cases is strongly recommended.

Implementation factor mapping of a pilot study of point-of-care C-reactive protein testing for respiratory tract infections in community pharmacy

Background

Explicit consideration of implementation factors in community pharmacy service development may facilitate widespread implementation and sustainability.

Objectives

This study involved mapping the methodology for the pilot study of point-of-care C-reactive protein (CRP) testing to support pharmacists' management of respiratory tract infections in Western Australian pharmacies against an implementation factor framework, focussing on the resources and training program provided to participating pharmacy staff.

Methods

Phase 1 involved post hoc mapping of the pilot study methodology against the framework previously described by Garcia-Cardenas et al.; phase 2 was an a priori evaluation of the resources and training program, involving pre-training, post-training, and post-pilot questionnaires administered to pharmacists and pharmacy assistants/interns. A mixed model analysis compared pharmacists' responses at the three time points.

Results

Employment of comprehensive strategies to optimise service feasibility and sustainability was demonstrated across the five domains of ‘professional service’, ‘pharmacy staff’, ‘pharmacy’, ‘local environment’ and ‘system’; further consideration of ‘consumer’ or ‘patient’ factors is needed to address issues such as patient refusal. Study pharmacists (n = 10) and pharmacy assistants/interns (n = 5) reported high levels of satisfaction with the training (100% ‘good’/‘excellent’). Pharmacists reported significantly improved attitudes towards, confidence in, and knowledge about CRP testing and service provision from pre- to post-training (p < 0.05). Positive perceptions were maintained at the post-pilot time point.

Conclusions

Post hoc mapping of implementation factors highlighted potential strengths and deficiencies of the current service model. Systematic, prospective mapping, coupled with strategies to explicitly emphasise the patient perspective, may have value in optimising service implementation or modifying future service delivery models.

Antibiotic prescribing rate after optimal near-patient C-reactive protein testing in acutely ill children presenting to ambulatory care (ARON project): protocol for a cluster-randomized pragmatic trial

INTRODUCTION

Children become ill quite often, mainly because of infections, most of which can be managed in the community. Many children are prescribed antibiotics which contributes to antimicrobial resistance and reinforces health-seeking behaviour. Point-of-care C reactive protein (POC CRP) testing, prescription guidance and safety-netting advice can help safely reduce antibiotic prescribing to acutely ill children in ambulatory care as well as save costs at a systems level.

METHODS AND ANALYSIS

The ARON (Antibiotic prescribing Rate after Optimal Near-patient testing in acutely ill children in ambulatory care) trial is a pragmatic cluster randomized controlled superiority trial with a nested process evaluation and will assess the clinical and cost effectiveness of a diagnostic algorithm, which includes a standardised clinical assessment, a POC CRP test, and safety-netting advice, in acutely ill children aged 6 months to 12 years presenting to ambulatory care. The primary outcome is antibiotic prescribing at the index consultation; secondary outcomes include clinical recovery, reconsultation, referral/admission to hospital, additional testing, mortality and patient satisfaction. We aim to recruit a total sample size of 6111 patients. All outcomes will be analysed according to the intent-to-treat approach. We will use a mixed-effect logistic regression analysis to account for the clustering at practice level.

ETHICS AND DISSEMINATION

The study will be conducted in compliance with the principles of the Declaration of Helsinki (current version), the principles of Good Clinical Practice and in accordance with all applicable regulatory requirements. Ethics approval for this study was obtained on 10 November 2020 from the Ethics Committee Research of University Hospitals Leuven under reference S62005. We will ensure that the findings of the study will be disseminated to relevant stakeholders other than the scientific world including the public, healthcare providers and policy-makers. The process evaluation that is part of this trial may provide a basis for an implementation strategy. If our intervention proves to be clinically and cost-effective, it will be essential to educate physicians about introducing the diagnostic algorithm including POC CRP testing and safety-netting advice in their daily practice.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT04470518. Protocol V.2.0 date 2 October 2020. (Pre-results).

Implementation and Use of Point-of-Care C-Reactive Protein Testing in Nursing Homes

OBJECTIVES

This study evaluated logistics, process data, and barriers/facilitators for the implementation and use of C-reactive protein point-of-care testing (CRP POCT) for suspected lower respiratory tract infections (LRTIs) in nursing home (NH) residents.

DESIGN

This process evaluation was performed alongside a cluster randomized, controlled trial (UPCARE study) to evaluate the effect of CRP POCT on antibiotic prescribing for suspected LRTIs in NH residents.

SETTING AND PARTICIPANTS

Eleven NHs in the Netherlands.

METHODS

Data sources for process data regarding intervention quality included a questionnaire among NH staff, logs, reports, and CRP POCT-analyzer records. Barriers and facilitators for implementation were assessed in focus group interviews with physicians and nurses from 3 NHs.

RESULTS

Correct patient selection for CRP POCT and generally continued CRP POCT use indicated good fidelity. The initial training and training of new employees seemed to fit the need, but some POCT-user group sizes had increased over time, which could have impeded frequent use. Users were generally satisfied with CRP POCT and perceived its use feasible and relevant. Facilitators for implementation were initial commitment and active initiation, followed by continued attention and enthusiasm for building routine practice and trust. Short lines of communication between staff, short distance to the POCT-analyzer, 24/7 coverage of staff, and a clear task division facilitated continued attention and routine practice.

CONCLUSIONS AND IMPLICATIONS

This process evaluation showed sufficient quality of providing CRP POCT in Dutch NHs. We processed findings of intervention quality and implementation knowledge into key recommendations for CRP POCT implementation in this setting. Future research could focus on CRP POCT use in countries with different organization of care in NHs.

Serum biomarkers to differentiate Gram-negative, Gram-positive and fungal infection in febrile patients

Introduction. Contamination of specimens and overuse of broad spectrum antibiotics contribute to false positives and false negatives, respectively. Therefore, useful and applicable biomarkers of bacteremia are still required.Hypothesis/Gap Statement. IL-6 can be used as a serum biomarker to discriminate among bacterial infections and fungal infections in febrile patients with a bloodstream infection.Aim. We aimed to evaluate the diagnostic efficiency of neutrophil/lymphocyte ratio (NLR), procalcitonin (PCT) and interleukin-6 (IL-6) in discriminating Gram-negative (G^-) bacteria from Gram-positive (G⁺) bacteria and fungi in febrile patients.Methodology. A total of 567 patients with fever were evaluated. Serum levels of IL-6, PCT, NLR and CRP were compared among a G^- group (n=188), a G⁺ group (n=168), a fungal group (n=38) and a culture negative group (n=173). Sensitivity, specificity, Yuden's index and area under the Receiver operating characteristic (ROC) curve (AUC) were obtained to analyse the diagnostic abilities of these biomarkers in discriminating bloodstream infection caused by different pathogens.Results. Serum IL-6 and PCT in the G^- group increased significantly when compared with both the G⁺ group and fungal group (P <0.05). AUC of IL-6 (0.767, 95 % CI:0.725-0.805) is higher than AUC of PCT (0.751, 95 % CI:0.708-0.796) in discriminating the G^- group from G⁺ group. When discriminating the G^- group from fungal group, the AUC of IL-6 (0.695, 95 % CI:0.651-0.747) with a cut-off value of 464.3 pg ml^-1 was also higher than the AUC of PCT (0.630, 95 % CI:0.585-0.688) with a cut-off value of 0.68 ng ml^-1. Additionally, AUC of NLR (0.685, 95 % CI:0.646-0.727) in discriminating the fungal group from G⁺ group at the cut-off value of 9.03, was higher than AUC of IL-6, PCT and CRP.Conclusion. This study suggests that IL-6 could be used as a serum biomarker to discriminate among bacterial infections and fungal infections in febrile patients with a bloodstream infection. In addition, NLR is valuable to discriminate fungal infections from Gram-positive infections in febrile patients with a bloodstream infection.

Point-of-care C-reactive protein testing to support the management of respiratory tract infections in community pharmacy: A feasibility study

BACKGROUND

Point-of-care (POC) C-reactive protein (CRP) testing is employed in European primary care settings to differentiate viral from bacterial respiratory tract infections (RTIs) the latter, requiring referral for antibiotics. This service has yet to be trialled in Australian community pharmacy to support over-the-counter RTI management.

OBJECTIVES

To evaluate the feasibility, based on clinical and operational outcomes, of POC CRP testing to support Western Australian community pharmacists' management of RTIs.

METHODS

Patients with RTI signs and symptoms were recruited from June-August 2019 at 5 community pharmacies. Trained pharmacists made recommendations based on participants' POC CRP levels and routine clinical assessment. Participants completed questionnaires and telephone follow-ups on Days 3 (by pharmacists) and 5 (by researchers) post-testing. Service provision and uptake were assessed in 3 separate weekly tally sheets.

RESULTS

Clinical outcomes: CRP levels among the 131 participants recruited were: < 5 mg/L (bacterial infection unlikely; n = 60; 45.8%); 5-19 mg/L (bacterial infection possible if suggestive routine assessment; n = 52; 39.7%) and 20-100 mg/L (bacterial infection likely if suggestive routine assessment; n = 19; 14.5%). Pharmacists' management included over-the-counter medicines (131, 100%), self-care advice (125, 95.4%) and immediate general practitioner (GP) referral (15, 11.5%). Sixty-five percent (76/117) of participants had recovered by Day 5. Operational outcomes: The services was provided in 21.2% of eligible RTI presentations, representing a service uptake rate of 28.1%. Post-CRP testing, 50.9% (58/114) of participants had changed perceptions regarding their need for antibiotics, with 14.3% (16/112) subsequently intending to seek a GP prescription. Consumer satisfaction was high (100%) and most participants (93.4%, 123/131) would utilise the service again.

CONCLUSIONS

POC CRP testing was a feasible and well-accepted strategy to facilitate community pharmacy as a triage point for RTI. Consumer confidence in the pharmacists' advice, supported by CRP testing, potentially reduced unnecessary GP visits and antibiotic prescribing.

Point-of-Care Biomarkers to Guide Antibiotic Prescription for Acute Febrile Illness in Sub-Saharan Africa: Promises and Caveats

Empiric malaria treatment in Sub-Saharan Africa has significantly decreased with the scaling-up of malaria rapid diagnostic tests; this coincided with a pronounced increase in empiric antibiotic prescriptions. In high-income countries, guidance for antibiotic prescriptions using biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) has reduced antibiotic use while safe-guarding patient safety. Importantly, several low-cost point-of-care CRP/PCT tests are currently available. However, only a few studies on the role of CRP/PCT in differentiating bacterial vs viral infections in acute febrile illness have been conducted in Sub-Saharan Africa. Studies from Central and West Africa (most of which is malaria-endemic) are particularly scarce, and only 1 has included adults. The evidence base for point-of-care use of CRP/PCT biomarkers in acute fever in Sub-Saharan Africa should be urgently built. Before engaging in clinical trials to assess clinical impact, pilot studies should be conducted to address key knowledge gaps including recommended CRP/PCT cutoff values and the effect of malaria coinfection.

Analytical performance and user-friendliness of five novel point-of-care D-dimer assays

D-dimer testing combined with a clinical assessment has become a standard pathway for ruling-out venous thromboembolism (VTE). Recently, novel Point-of-Care (POC) D-dimer assays have been introduced, enabling low-volume blood sampling for rapid exclusion of VTE in a one-step procedure. We assessed the analytical validity and user-friendliness of a set of these novel POC D-dimer assays, and compared the results with a standard laboratory assay. Plasma samples were run on our reference assay (STA-Liatest D-di PLUS^®) and five POC assays: Nano-Checker 710^®, AFIAS-1^®; iChroma-II^®; Standard F200^® and Hipro AFS/1^®). After evaluating imprecision, Pearson Product-Moment correlation coefficients were calculated, Passing Bablok regression was performed and Bland-Altman plots were generated. User-friendliness was evaluated using the System Usability Scale (SUS). A set of 238 plasma samples of patients clinically suspected of VTE in general practice was available for analysis. Only one POC D-dimer assay (Nano-Checker 710) demonstrated an insufficient degree of imprecision. Pearson correlation coefficients and mean biases ranged from 0.68 to 0.93 and -165 to -53 μg/L respectively, and concordance with our reference assay varied from 71.8% to 89.5% using a 500 μg/L cut-off point. While we found considerable variation in overall user-friendliness, most devices were judged easy to use. In view of our findings regarding analytical performance and user-friendliness, we consider most of the novel POC D-dimer assays can be used in settings outside of the laboratory such as general practice, combining the possibility of multi-testing with low-volume capillary blood sampling and processing times of less than 15 min.

Using point-of-care C-reactive protein to guide antibiotic prescribing for lower respiratory tract infections in elderly nursing home residents (UPCARE): study design of a cluster randomized controlled trial

Background

Antibiotics are over-prescribed for lower respiratory tract infections (LRTI) in nursing home residents due to diagnostic uncertainty. Inappropriate antibiotic use is undesirable both on patient level, considering their exposure to side effects and drug interactions, and on societal level, given the development of antibiotic resistance. C-reactive protein (CRP) point-of-care testing (POCT) may be a promising diagnostic tool to reduce antibiotic prescribing for LRTI in nursing homes. The UPCARE study will evaluate whether the use of CRP POCT for suspected LRTI is (cost-) effective in reducing antibiotic prescribing in the nursing home setting.

Methods/design

A cluster randomized controlled trial will be conducted in eleven nursing homes in the Netherlands, with the nursing home as the unit of randomization. Residents with suspected LRTI who reside at a psychogeriatric, somatic, or geriatric rehabilitation ward are eligible for study participation. Nursing homes in the intervention group will provide care as usual with the possibility to use CRP POCT, and the control group will provide care as usual without CRP POCT for residents with (suspected) LRTI. Data will be collected from September 2018 for approximately 1.5 year, using case report forms that are integrated in the electronic patient record system. The primary study outcome is antibiotic prescribing for suspected LRTI at index consultation (yes/no).

Discussion

This is the first randomised trial to evaluate the effect of nursing home access to and training in the use of CRP POCT on antibiotic prescribing for LRTI, yielding high-level evidence and contributing to antibiotic stewardship in the nursing home setting. The relatively broad inclusion criteria and the pragmatic study design add to the applicability and generalizability of the study results.

Trial registration

Netherlands Trial Register, Trial NL5054. Registered 29 August 2018.

Economic considerations support C-reactive protein testing alongside malaria rapid diagnostic tests to guide antimicrobial therapy for patients with febrile illness in settings with low malaria endemicity

Malaria is no longer a common cause of febrile illness in many regions of the tropics. In part, this success is a result of improved access to accurate diagnosis and effective anti-malarial treatment, including in many hard-to-reach rural areas. However, in these settings, management of other causes of febrile illness remains challenging. Health systems are often weak and other than malaria rapid tests no other diagnostics are available. With millions of deaths occurring annually due to treatable bacterial infections and the ever increasing spread of antimicrobial resistance, improvement in the management of febrile illness is a global public health priority. Whilst numerous promising point-of-care diagnostics are in the pipeline, substantial progress can be made in the interim with existing tools: C-reactive protein (CRP) is a highly sensitive and moderately specific biomarker of bacterial infection and has been in clinical use for these purposes for decades, with dozens of low-cost devices commercially available. This paper takes a health-economics approach to consider the possible advantages of CRP point-of-care tests alongside rapid diagnostic tests for malaria, potentially in a single multiplex device, to guide antimicrobial therapy for patients with febrile illness. Three rudimentary assessments of the costs and benefits of this approach all indicate that this is likely to be cost-effective when considering the incremental costs of the CRP tests as compared with either (i) the improved health outcomes for patients with bacterial illnesses; (ii) the costs of antimicrobial resistance averted; or (iii) the economic benefits of better management of remaining malaria cases and shorter malaria elimination campaigns in areas of low transmission. While CRP-guided antibiotic therapy alone cannot resolve all challenges associated with management of febrile illness in remote tropical settings, in the short-term a multiplexed CRP and malaria RDT could be highly cost-effective and utilize the well-established funding and distribution systems already in place for malaria RDTs. These findings should spark further interest amongst industry, academics and policy-makers in the development and deployment of such diagnostics, and discussion on their geographically appropriate use.

Performance of the Ankylosing Spondylitis Disease Activity Score based on a quick quantitative C-reactive protein assay in patients with axial spondyloarthritis

OBJECTIVES

To evaluate the performance of the Ankylosing Spondylitis Disease Activity Score based on a validated quick quantitative C-reactive protein assay (ASDAS-qCRP) as compared to ASDAS based on a routine lab CRP assay (ASDAS-CRP) and ASDAS based on erythrocyte sedimentation rate (ASDAS-ESR).

METHODS

Disease activity assessment was performed in 50 patients with axial spondyloarthritis (axSpA). Routine lab CRP was measured in the central lab while the quantitative quick-CRP assay and ESR measurements were performed locally. ASDAS-CRP, ASDAS-qCRP and ASDAS-ESR were subsequently calculated.

RESULTS

The mean (±SD) serum level of the routine lab CRP (6.2±8.3mg/l) was lower than of the quick-CRP (7.4±8.4mg/l) (P<0.05). Whereat, there was no significant difference in the mean values of ASDAS-CRP and ASDAS-qCRP in axSpA patients (2.70±0.94 and 2.74±0.96, respectively, P=0.069), while the ASDAS-ESR (2.85±1.0) was significantly higher than ASDAS-CRP (P=0.036) and numerically higher than ASDAS-qCRP (P=0.125). In 47 of the 50 cases of axSpA (94%), patients were assigned to the same disease activity category according to ASDAS-CRP and ASDAS-qCRP.

CONCLUSIONS

ASDAS-qCRP performed similarly well compared to ASDAS-CRP with the absolute agreement on the disease activity category according to the ASDAS of 94%. ASDAS-qCRP is, therefore, feasible for an immediate decision-making in clinical practice and trials aimed at treating to target.

A multicenter evaluation of a point of care CRP Test

BACKGROUND

Point-of-care (POC) C-reactive protein (CRP) testing in the primary healthcare setting is a cost-effective approach for reducing antibiotic prescriptions, but has yet to be widely adopted.

METHODS

Analytical performance of the cobas CRP Test on the cobas b 101 system was evaluated at three POC sites and one reference laboratory. Within-run (repeatability), within-laboratory (intermediate precision), and between-laboratory precision (reproducibility) were assessed. Method comparison (reference test: CRPNX reagent [cobas c 501 module]) and matrix/lot-to-lot comparison experiments were conducted using prospectively collected blood samples from 217 adults (apparently healthy or with clinically relevant conditions). Usability and reliability were assessed by questionnaire and error reporting.

RESULTS

Coefficients of variation (CV) for repeatability and intermediate precision ranged from 1.7%-4.0% and 1.9%-4.5%, respectively, for human serum pools containing CRP 4.7-350.7 mg/L; repeatability in clinical samples ranged from 1.6%-5.9% (3.3-360.3 mg/L). CVs for reproducibility ranged from 2.5%-4.0% (4.7-344.3 mg/L). CRP concentrations were comparable for capillary whole blood, serum, Li-heparin whole blood/plasma, K2 and K3 EDTA whole blood/plasma (Pearson's r ≥ 0.996), and among three CRP Test lots (r ≥ 0.993). Clinically relevant CRP concentrations measured with the CRP Test showed good agreement with those measured by CRPNX reagent (serum, weighted Deming regression y = 0.97× + 0.11; Pearson's r ≥ 0.996). The overall mean usability score was 4.18/5 and the error rate across 9378 tests was 1.00%.

CONCLUSIONS

The cobas CRP Test on the cobas b 101 system demonstrates robust analytic performance when used by healthcare professionals in the POC setting.

Impact of point-of-care C reactive protein in ambulatory care: a systematic review and meta-analysis

OBJECTIVE

The aim of this review was to collate all available evidence on the impact of point-of-care C reactive protein (CRP) testing on patient-relevant outcomes in children and adults in ambulatory care.

DESIGN

This was a systematic review to identify controlled studies assessing the impact of point-of-care CRP in patients presenting to ambulatory care services. Ovid Medline, Embase, Cochrane Database of Systematic Reviews, Cochrane CENTRAL, DARE, Science Citation Index were searched from inception to March 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Controlled studies assessing the impact of point-of-care CRP in patients presenting to ambulatory care services, measuring a change in clinical care, including but not limited to antibiotic prescribing rate, reconsultation, clinical recovery, patient satisfaction, referral and additional tests. No language restrictions were applied.

DATA EXTRACTION

Data were extracted on setting, date of study, a description of the intervention and control group, patient characteristics and results. Methodological quality of selected studies and assessment of potential bias was assessed independently by two authors using the Cochrane Risk of Bias tool.

RESULTS

11 randomised controlled trials and 8 non-randomised controlled studies met the inclusion criteria, reporting on 16 064 patients. All included studies had a high risk of performance and selection bias. Compared with usual care, point-of-care CRP reduces immediate antibiotic prescribing (pooled risk ratio 0.81; 95% CI 0.71 to 0.92), however, at considerable heterogeneity (I2=72%). This effect increased when guidance on antibiotic prescribing relative to the CRP level was provided (risk ratios of 0.68; 95% CI 0.63 to 0.74 in adults and 0.56; 95% CI 0.33 to 0.95 in children). We found no significant effect of point-of-care CRP testing on patient satisfaction, clinical recovery, reconsultation, further testing and hospital admission.

CONCLUSIONS

Performing a point-of-care CRP test in ambulatory care accompanied by clinical guidance on interpretation reduces the immediate antibiotic prescribing in both adults and children. As yet, available evidence does not suggest an effect on other patient outcomes or healthcare processes.

PROSPERO REGISTRATION NUMBER

CRD42016035426; Results.

Point-of-care C reactive protein to identify serious infection in acutely ill children presenting to hospital: prospective cohort study

OBJECTIVE

Acute infection is the most common presentation of children to hospital. A minority of these infections are serious, but early recognition and adequate management are essential. We aimed to develop improved tools to assess children attending ambulatory hospital care, integrating clinical features with point-of-care C reactive protein (CRP).

DESIGN

Prospective observational diagnostic study.

SETTING AND PATIENTS

5517 acutely ill children (1 month-16 years) presenting to 106 paediatricians at six outpatient clinics and six emergency departments in Belgium.

INDEX TEST

Point-of-care CRP alongside vital signs and objective symptoms measurements.

MAIN OUTCOME

Hospital admission for >24 hours with a serious infection <5 days after presentation.

RESULTS

An algorithm was developed consisting of clinical features and CRP. This achieved 97.1% (95% CI 94.3% to 98.7%) sensitivity and 99.6% (95% CI 99.2% to 99.8%) negative predictive value, excluding serious infections in 36.4% of children. It stratifies patients into three groups based on CRP level: high-risk group with CRP >75 mg/L (26.8% risk of infection), intermediate-risk group with CRP 20-75 mg/L and at least one of seven clinical features (8.1%), and lower risk group with CRP <20 mg/L with at least one of the 11 features (3.8%). Children in intermediate-risk or low-risk groups with normal clinical assessment have 0.6% and 0.4% risk of serious infections, respectively.

CONCLUSIONS

Conducting a CRP test may first enable children to be stratified into three risk groups, guiding assessment of clinical features that could be performed by junior doctors or nurses. In one-third of acutely ill children, the algorithm could exclude serious infection. Prospective validation of the algorithm is needed.

CLINICAL TRIAL REGISTRATION

NCT02024282 (post-results).

A systematic evaluation of immunoassay point-of-care testing to define impact on patients' outcomes

Background Point-of-care testing has been developed to provide rapid test results. Most published studies focus on analytical performance, neglecting its impact on patient outcomes. Objective To review the analytical performance and accuracy of point-of-care testing specifically planned for immunoassay and to evaluate the impact of faster results on patient management. Methods A search of electronic databases for studies reporting immunoassay results obtained in both point-of-care testing and central laboratory scenarios was performed. Data were extracted concerning the study details, and the methodological quality was assessed. The analytical characteristics and diagnostic accuracy of six points-of-care testing: troponin, procalcitonin, parathyroid hormone, brain natriuretic peptide, C-reactive protein and neutrophil gelatinase-associated lipocalin were evaluated. Results A total of 116 scientific papers were analysed. Studies measuring procalcitonin, parathyroid hormone and neutrophil gelatinase-associated lipocalin reported a limited impact on diagnostic decisions. Seven studies measuring C-reactive protein claimed a significant reduction of antibiotic prescription. Several authors evaluated brain natriuretic peptide or troponin reporting faster decision-making without any improvement in clinical outcome. Forty-four per cent of studies reported analytical data, showing satisfactory correlations between results obtained through point-of-care testing and central laboratory setting. Half of studies defined the diagnostic accuracy of point-of-care testing as acceptable for troponin (median sensitivity and specificity: 74% and 94%, respectively), brain natriuretic peptide (median sensitivity and specificity: 82% and 88%, respectively) and C-reactive protein (median sensitivity and specificity 85%). Conclusions Point-of-care testing immunoassay results seem to be reliable and accurate for troponin, brain natriuretic peptide and C-reactive protein. The satisfactory analytical performance, together with an excellent practicability, suggests that it could be a consistent tool in clinical practice, but data are lacking regarding the patient outcomes.

Effect of Participating in a Quality Improvement System over Time for Point-of-Care C-Reactive Protein, Glucose, and Hemoglobin Testing

BACKGROUND

Users of point-of-care testing (POCT) in Norway participate in a quality improvement system that includes education and guidance in safe laboratory management along with participation in external quality assurance schemes (EQAS).

The aim of this study was to identify the effect on the analytical performance of POCT C-reactive protein (CRP), glucose, and hemoglobin (Hb) with the use of a quality improvement system over time and to identify which factors are associated with good performance.

METHODS

Participants' results from 19 EQAS for CRP, glucose, and Hb from 2006 to 2015 along with information on the instruments used and different practice characteristics were analyzed. Logistic regression analysis was used to evaluate the factors associated with good laboratory performance. An instrument evaluation and comparison for CRP determination was performed by using commutable EQA material.

RESULTS

The mean number of participants in each EQAS was 2134, 2357, and 2271 for CRP, glucose, and Hb, respectively. The percentage of good participant performances increased gradually whereas that of poor performances decreased with participation in a quality improvement system over 9 years for all 3 analytes. Independent factors associated with good performance were type of instrument, the number of times performing EQA, performing internal QC weekly, performing 10 or more tests weekly, and having laboratory-qualified personnel perform the tests. Considering CRP instrument performance, Afinion and QuikRead exhibited the lowest systematic deviation.

CONCLUSIONS

The analytical quality of CRP, glucose, and Hb testing is improved by systematic participation in a quality improvement system over time.

Should all acutely ill children in primary care be tested with point-of-care CRP: a cluster randomised trial

BACKGROUND

Point-of-care blood C-reactive protein (CRP) testing has diagnostic value in helping clinicians rule out the possibility of serious infection. We investigated whether it should be offered to all acutely ill children in primary care or restricted to those identified as at risk on clinical assessment.

METHODS

Cluster randomised controlled trial involving acutely ill children presenting to 133 general practitioners (GPs) at 78 GP practices in Belgium. Practices were randomised to undertake point-of-care CRP testing in all children (1730 episodes) or restricted to children identified as at clinical risk (1417 episodes). Clinical risk was assessed by a validated clinical decision rule (presence of one of breathlessness, temperature ≥ 40 °C, diarrhoea and age 12-30 months, or clinician concern). The main trial outcome was hospital admission with serious infection within 5 days. No specific guidance was given to GPs on interpreting CRP levels but diagnostic performance is reported at 5, 20, 80 and 200 mg/L.

RESULTS

Restricting CRP testing to those identified as at clinical risk substantially reduced the number of children tested by 79.9 % (95 % CI, 77.8-82.0 %). There was no significant difference between arms in the number of children with serious infection who were referred to hospital immediately (0.16 % vs. 0.14 %, P = 0.88). Only one child with a CRP < 5 mg/L had an illness requiring admission (a child with viral gastroenteritis admitted for rehydration). However, of the 80 children referred to hospital to rule out serious infection, 24 (30.7 %, 95 % CI, 19.6-45.6 %) had a CRP < 5 mg/L.

CONCLUSIONS

CRP testing should be restricted to children at higher risk after clinical assessment. A CRP < 5 mg/L rules out serious infection and could be used by GPs to avoid unnecessary hospital referrals.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02024282 (registered on 14^th September 2012).

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.

Analysis of recruitment in a pragmatic observational study on C-reactive protein point-of-care testing in primary care

INTRODUCTION

Failure to recruit all eligible study patients can lead to biased results. Little is known on selective patient recruitment in studies on implementation of diagnostic devices.

OBJECTIVES

The aim of this observational study was to measure recruitment of patients in an implementation study in primary care on use of point-of-care (POC) C-reactive protein (CRP) and to evaluate recruitment bias and its impact on the study endpoint.

METHODS

In a cross-sectional observational study on POC CRP implementation and related antibiotics prescribing, we compared included patients with all eligible patients to assess the representativeness of the included subjects. Eligible patients were adults presenting with acute cough in primary care between March and September 2012. The frequency of POC CRP testing and the proportion of prescribed antibiotics were compared between recruited and non-recruited patients. As measure of bias, odds ratios (ORs) with accompanying 95% confidence intervals (CIs) for the association between CRP level (<20 mg/l or not) and antibiotic prescribing were computed.

RESULTS

Of all 1473 eligible patients 348 (24%) were recruited. In recruited patients, POC CRP tests were conducted and antibiotics prescribed more frequently as compared to non-recruited patients (81% versus 6% and 44% versus 29%, respectively). The ORs were 18.2 (95%CI: 9.6-34.3), 30.5 (95%CI: 13.2-70.3) and 3.8 (95%CI: 0.9-14.8) respectively in all eligible patients, the recruited and the non-recruited patients.

CONCLUSION

Selective recruitment resulted in an overestimation of POC CRP test use and antibiotic prescribing.

C-reactive protein point-of-care testing and associated antibiotic prescribing

BACKGROUND

In clinical trials, the potential of point-of-care (POC) C-reactive protein (CRP) tests was demonstrated in decreasing antibiotic prescribing in adults with acute cough in general practice, but effects of implementation are unknown.

OBJECTIVE

To determine the overall effect of POC CRP testing on antibiotic prescribing rate in general practice.

METHODS

In an observational study, GPs were instructed to use POC CRP in adults with acute cough following current guidelines. After routine history taking and physical examination, they reported whether they intended to prescribe antibiotics ('pre-test decision'). They reported their revised decision after receiving the POC CRP test result ('post-test decision'). Primary outcome was the percentage of patients in whom the GP changed his or her decision to prescribe antibiotics. Secondary outcome was the difference between 'pre-test' and 'post-test' antibiotic prescribing % at group level.

RESULTS

A total of 40 GPs enrolled 939 patients, 78% of whom were tested for CRP. GPs changed their decision after POC CRP testing in 200 patients (27%). Antibiotic prescribing before and after CRP testing did not differ ('pre-test' 31%, 'post-test' 28%; 95% confidence interval of difference -7 to 1). In 41% of the tested patients, the indication for testing was in accordance with the guidelines.

CONCLUSION

POC CRP influenced GPs to change their decision about antibiotic prescribing in patients with acute cough. POC CRP testing does not reduce overall antibiotic prescribing by GPs who already have a low antibiotic prescribing rate.

Accuracy of commercially available c-reactive protein rapid tests in the context of undifferentiated fevers in rural Laos

BACKGROUND

C-Reactive Protein (CRP) has been shown to be an accurate biomarker for discriminating bacterial from viral infections in febrile patients in Southeast Asia. Here we investigate the accuracy of existing rapid qualitative and semi-quantitative tests as compared with a quantitative reference test to assess their potential for use in remote tropical settings.

METHODS

Blood samples were obtained from consecutive patients recruited to a prospective fever study at three sites in rural Laos. At each site, one of three rapid qualitative or semi-quantitative tests was performed, as well as a corresponding quantitative NycoCard Reader II as a reference test. We estimate the sensitivity and specificity of the three tests against a threshold of 10 mg/L and kappa values for the agreement of the two semi-quantitative tests with the results of the reference test.

RESULTS

All three tests showed high sensitivity, specificity and kappa values as compared with the NycoCard Reader II. With a threshold of 10 mg/L the sensitivity of the tests ranged from 87-98 % and the specificity from 91-98 %. The weighted kappa values for the semi-quantitative tests were 0.7 and 0.8.

CONCLUSION

The use of CRP rapid tests could offer an inexpensive and effective approach to improve the targeting of antibiotics in remote settings where health facilities are basic and laboratories are absent. This study demonstrates that accurate CRP rapid tests are commercially available; evaluations of their clinical impact and cost-effectiveness at point of care is warranted.

Performance of C-reactive protein and procalcitonin to distinguish viral from bacterial and malarial causes of fever in Southeast Asia

BACKGROUND

Poor targeting of antimicrobial drugs contributes to the millions of deaths each year from malaria, pneumonia, and other tropical infectious diseases. While malaria rapid diagnostic tests have improved use of antimalarial drugs, there are no similar tests to guide the use of antibiotics in undifferentiated fevers. In this study we estimate the diagnostic accuracy of two well established biomarkers of bacterial infection, procalcitonin and C-reactive protein (CRP) in discriminating between common viral and bacterial infections in malaria endemic settings of Southeast Asia.

METHODS

Serum procalcitonin and CRP levels were measured in stored serum samples from febrile patients enrolled in three prospective studies conducted in Cambodia, Laos and, Thailand. Of the 1372 patients with a microbiologically confirmed diagnosis, 1105 had a single viral, bacterial or malarial infection. Procalcitonin and CRP levels were compared amongst these aetiological groups and their sensitivity and specificity in distinguishing bacterial infections and bacteraemias from viral infections were estimated using standard thresholds.

RESULTS

Serum concentrations of both biomarkers were significantly higher in bacterial infections and malaria than in viral infections. The AUROC for CRP in discriminating between bacterial and viral infections was 0.83 (0.81-0.86) compared with 0.74 (0.71-0.77) for procalcitonin (p < 0.0001). This relative advantage was evident in all sites and when stratifying patients by age and admission status. For CRP at a threshold of 10 mg/L, the sensitivity of detecting bacterial infections was 95% with a specificity of 49%. At a threshold of 20 mg/L sensitivity was 86% with a specificity of 67%. For procalcitonin at a low threshold of 0.1 ng/mL the sensitivity was 90% with a specificity of 39%. At a higher threshold of 0.5 ng/ul sensitivity was 60% with a specificity of 76%.

CONCLUSION

In samples from febrile patients with mono-infections from rural settings in Southeast Asia, CRP was a highly sensitive and moderately specific biomarker for discriminating between viral and bacterial infections. Use of a CRP rapid test in peripheral health settings could potentially be a simple and affordable measure to better identify patients in need of antibacterial treatment and part of a global strategy to combat the emergence of antibiotic resistance.

The added diagnostic value of five different C-reactive protein point-of-care test devices in detecting pneumonia in primary care: A nested case-control study

BACKGROUND

The results obtained from various point-of-care (POC) test devices for estimating C-reactive protein (CRP) levels in a laboratory setting differ when compared to a laboratory reference test. We aimed to determine whether such differences meaningfully affect the accuracy and added diagnostic value in predicting radiographic pneumonia in adults presenting with acute cough in primary care.

METHODS

A nested case control study of adult patients presenting with acute cough in 12 different European countries (the Genomics to combat Resistance against Antibiotics in Community-acquired LRTI in Europe [GRACE] Network). Venous blood samples from 100 patients with and 100 patients without pneumonia were tested with five different POC CRP tests and a laboratory analyzer. Single test accuracy values and the added value of CRP to symptoms and signs were calculated.

RESULTS

Single test accuracy values showed similar results for all five POC CRP tests and the laboratory analyzer. The area under the curve of the different POC CRP tests and the laboratory analyzer (range 0.79-0.80) were all comparable and higher than the clinical model without CRP (0.70). Multivariable odds ratios were the same (1.2) for all CRP tests.

CONCLUSIONS

Five POC CRP test devices and the laboratory analyzer performed with similar accuracy in detecting pneumonia both as single test, and when used in addition to clinical findings. Variability in results obtained from standard CRP laboratory and POC test devices do not translate into clinically relevant differences when used for prediction of pneumonia in patients with acute cough in primary care.