A clinician's experience of using the Cardiac Reader NT-proBNP point-of-care assay in a clinical setting

Mixed‐methods evaluation of a multifaceted heart failure intervention in general practice: the OSCAR‐HF pilot study

AIMS

Heart failure (HF) is an important health problem for which multidisciplinary care is recommended, yet few studies involve primary care practitioners in the multidisciplinary management of HF. We set up a multifaceted prospective observational trial, OSCAR-HF, piloting audit and feedback, natriuretic peptide testing at the point of care, and the assistance of a specialist HF nurse in primary care. The aim was to optimize HF care in general practice.

METHODS AND RESULTS

This is an analysis at 6 month follow-up of the study interventions of the OSCAR-HF pilot study, a nonrandomized, noncontrolled prospective observational trial conducted in eight Belgian general practices [51 general practitioners (GPs)]. Patients who were assessed by their GP to have HF constituted the OSCAR-HF study population. We used descriptive statistics and mixed-effects modelling for the quantitative analysis and thematic analysis of the focus group interviews. There was a 10.2% increase in the registered HF population after 6 months of follow-up (n = 593) compared with baseline (n = 538) and a 27% increase in objectified HF diagnoses (baseline n = 359 to 456 at T6 M). Natriuretic peptide testing (with or without referral) accounted for 54% (n = 60/111) of the newly registered HF diagnoses. There was no difference in the proportion of patients with HF with reduced ejection fraction who received their target dosage of renin-angiotensin-aldosterone system inhibitors or beta-blockers at 6 months compared with baseline (P = 0.9). Patients who received an HF nurse intervention (n = 53) had significantly worse quality of life at baseline [difference in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score 9.2 points; 95% confidence interval (CI) 4.0, 14] and had a significantly greater improvement in quality-of-life scores at the 6 month follow-up [change in MLHFQ score -9.8 points; 95% CI -15, -4.5] than patients without an HF nurse intervention. GPs found audit and feedback valuable but time intensive. Natriuretic peptides were useful, but the point-of-care test was impractical, and the assistance of an HF nurse was a useful addition to routine HF care.

CONCLUSIONS

The use of audit and feedback combined with natriuretic peptide testing was a successful strategy to increase the number of registered and objectified HF diagnoses at 6 months. GPs and HF nurses selected patients with worse quality-of-life scores at baseline for the HF nurse intervention, which led to a significantly greater improvement in quality-of-life scores at the 6 month follow-up compared with patients without an HF nurse intervention. The interventions were deemed feasible and useful by the participating GPs with some specific remarks that can be used for optimization.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02905786), registered on 14 September 2016 at https://clinicaltrials.gov/.

Elevated proBNP levels are associated with disease severity, cardiac dysfunction, and mortality in congenital diaphragmatic hernia

BACKGROUND

Cardiac dysfunction is a key determinant of outcome in congenital diaphragmatic hernia (CDH). Pro-b-type natriuretic peptide (proBNP) is used as a prognosticator in heart failure and cardiomyopathy. We hypothesized that proBNP levels would be associated with ventricular dysfunction and high-risk disease in CDH.

METHODS

Patients in the CDH Study Group (CDHSG) from 2015-2019 with at least one proBNP value were included. Ventricular function was determined using echocardiograms from the first 48 h of life.

RESULTS

A total of 2,337 patients were identified, and 212 (9%) had at least one proBNP value. Of those, 3 (1.5%) patients had CDHSG stage A defects, 58 (29.6%) B, 111 (56.6%) C, and 24 (12.2%) D. Patients with high-risk defects (Stage C/D) had higher proBNP compared with low-risk defects (Stage A/B) (14,281 vs. 5,025, p = 0.007). ProBNP was significantly elevated in patients who died (median 14,100, IQR 4,377-22,900 vs 4,911, IQR 1,883-9,810) (p<0.001). Ventricular dysfunction was associated with higher proBNP than normal ventricular function (8,379 vs. 4,778, p = 0.005). No proBNP value was both sensitive and specific for ventricular dysfunction (AUC=0.61).

CONCLUSION

Among CDH patients, elevated proBNP was associated with high-risk defects, ventricular dysfunction, and mortality. ProBNP shows promise as a biomarker in CDH-associated cardiac dysfunction.

Optimising standards of care of heart failure in general practice the OSCAR-HF pilot study protocol

Background: Heart failure (HF) imposes a burden for patients and health economics. General practitioners (GPs) are confronted with the broadest range of HF management. Although guidelines exist, they are not fully implemented in the Belgian health care system. Methods: We will conduct a non-randomised, non-controlled prospective observational trial (six months follow-up) to implement a multifaceted intervention in Belgian general practice to support GPs in the implementation of evidence-based HF guidelines. The multifaceted intervention consists of an audit and feedback method to detect previously unrecognised patients with HF and to increase awareness for proactive HF management, an NT-proBNP point-of-care test to improve detection and adequate diagnosis of patients with HF and a specialist HF nurse to assist GPs in the education of patients, optimisation of treatment and follow-up after hospitalisation. All patients aged 40 years and older with a confirmed diagnosis of HF by their GP based on the clinical audit are eligible for participation. The main objective of this pilot study is to evaluate the feasibility of this multifaceted intervention and the evolution of predefined quality indicators. We will measure the impact on HF diagnosis, medication optimisation, multidisciplinary follow-up and patients' quality of life after six months. Additionally, the experiences of GPs and investigators will be studied. Conclusions: Heart failure is an important health problem in which GPs play a key role. Therefore, we will evaluate the feasibility of a multifaceted intervention to optimise diagnosis as well as implement the guideline recommended therapies in patients with HF in general practice.

Accuracy, user-friendliness and usefulness of the Cobas h232 point-of-care test for NT-proBNP in primary care

Aims

N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been shown to be useful for ruling out heart failure in primary care. In this study, we examined the accuracy of the Cobas h232 point-of-care (POC) instrument in primary care compared with an in-hospital measurement. Furthermore, we investigated the user-friendliness and usefulness of the POC device.

Methods

Five general practitioner (GP) groups were asked to evaluate adult patients who were suspected of having heart failure and to test NT-proBNP with the Cobas h232. The samples were subsequently delivered to and analysed at a central hospital laboratory by the Cobas e602 using conventional transport and storage. Difference between the paired measurements was analysed using a percentage difference plot, and correlation was assessed using Passing-Bablok linear regression analysis. User-friendliness and usefulness were assessed using semistructured questionnaires.

Results

Nineteen GPs studied 94 patients. Passing-Bablok analysis showed a slope of 1.05 (95% CI 1.00 to 1.11) (R2=0.97). The percentage difference plot showed a mean difference of 15.7% (95% CI −46.0% to –77.4%). User-friendliness and usefulness had median scores of 4 or 5 on a five-point Likert scale. Eighteen out of 19 GPs confirmed that the device influenced their clinical practice. During the study, GPs’ confidence in using NT-proBNP increased significantly from a mean score of 4.4 (95% CI 3.2 to 5.6) to 7.6 out of 10 (95% CI 7.1 to 8.2).

Conclusions

The Cobas h232 NT-proBNP POC test proved to be an accurate, user-friendly and useful test in primary care. Nearly all participating GPs were convinced that the test could benefit clinical decision making.

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.

Evidence for models of diagnostic service provision in the community: literature mapping exercise and focused rapid reviews

Background

Current NHS policy favours the expansion of diagnostic testing services in community and primary care settings.

Objectives

Our objectives were to identify current models of community diagnostic services in the UK and internationally and to assess the evidence for quality, safety and clinical effectiveness of such services. We were also interested in whether or not there is any evidence to support a broader range of diagnostic tests being provided in the community.

Review methods

We performed an initial broad literature mapping exercise to assess the quantity and nature of the published research evidence. The results were used to inform selection of three areas for investigation in more detail. We chose to perform focused reviews on logistics of diagnostic modalities in primary care (because the relevant issues differ widely between different types of test); diagnostic ultrasound (a key diagnostic technology affected by developments in equipment); and a diagnostic pathway (assessment of breathlessness) typically delivered wholly or partly in primary care/community settings. Databases and other sources searched, and search dates, were decided individually for each review. Quantitative and qualitative systematic reviews and primary studies of any design were eligible for inclusion.

Results

We identified seven main models of service that are delivered in primary care/community settings and in most cases with the possible involvement of community/primary care staff. Not all of these models are relevant to all types of diagnostic test. Overall, the evidence base for community- and primary care-based diagnostic services was limited, with very few controlled studies comparing different models of service. We found evidence from different settings that these services can reduce referrals to secondary care and allow more patients to be managed in primary care, but the quality of the research was generally poor. Evidence on the quality (including diagnostic accuracy and appropriateness of test ordering) and safety of such services was mixed.

Conclusions

In the absence of clear evidence of superior clinical effectiveness and cost-effectiveness, the expansion of community-based services appears to be driven by other factors. These include policies to encourage moving services out of hospitals; the promise of reduced waiting times for diagnosis; the availability of a wider range of suitable tests and/or cheaper, more user-friendly equipment; and the ability of commercial providers to bid for NHS contracts. However, service development also faces a number of barriers, including issues related to staffing, training, governance and quality control.

Limitations

We have not attempted to cover all types of diagnostic technology in equal depth. Time and staff resources constrained our ability to carry out review processes in duplicate. Research in this field is limited by the difficulty of obtaining, from publicly available sources, up-to-date information about what models of service are commissioned, where and from which providers.

Future work

There is a need for research to compare the outcomes of different service models using robust study designs. Comparisons of ‘true’ community-based services with secondary care-based open-access services and rapid access clinics would be particularly valuable. There are specific needs for economic evaluations and for studies that incorporate effects on the wider health system. There appears to be no easy way of identifying what services are being commissioned from whom and keeping up with local evaluations of new services, suggesting a need to improve the availability of information in this area.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

NT-proBNP on Cobas h 232 in point-of-care testing: Performance in the primary health care versus in the hospital laboratory

BACKGROUND

NT-proBNP may be useful for ruling out heart failure in primary health care. In this study we examined the analytical quality of NT-proBNP in primary health care on the Cobas h 232 point-of-care instrument compared with measurements performed in a hospital laboratory.

MATERIALS AND METHODS

Blood samples requested for NT-proBNP were collected in primary health care (n = 95) and in a hospital laboratory (n = 107). NT-proBNP was measured on-site on Cobas h 232 instruments both in primary health care centres and at the hospital laboratory and all samples were also analyzed with a comparison method at the hospital. Precision, trueness, accuracy, and lot-variation were determined at different concentration levels and evaluated according to acceptance criteria. Furthermore user-friendliness was assessed by questionnaires.

RESULTS

For Cobas h 232 repeatability CV was 8.5-10.7% in the hospital setting and 5.3-10.0% in the primary health care and within the analytical quality specifications, but higher than with the comparison method (< 4%). NT-proBNP results obtained in primary health care were significantly higher than by the hospital comparison method (bias ranged from 14.3-23.7%), whereas there was no significant bias when Cobas h 232 was used in the hospital setting (bias ranged from - 4.9 to 7.0%). User-friendliness of Cobas h 232 was overall acceptable.

CONCLUSION

Cobas h 232 point-of-care instrument for measurement of NT-proBNP performed satisfactorily with regard to precision, user-friendliness, and lot-variation. A decrease in NT-proBNP levels observed in samples transported to a central laboratory needs further attention and investigation.

A management programme for suspected heart failure in primary care in cooperation with specialists in cardiology

BACKGROUND

The diagnosis of new onset congestive heart failure (CHF) is often difficult as symptoms and signs are non-specific. Proper diagnostic investigations and treatments are underused in primary care.

OBJECTIVE

To describe a management programme for patients with suspected CHF in primary care in cooperation with specialists in cardiology.

METHODS

Prospective study of 102 consecutive primary care patients with suspected new onset CHF referred to an easily accessible hospital-based cardiology outpatient clinic management programme. Following clinical examination, ECG, echocardiography, blood chemistry including NT-proBNP, and assessment of NYHA class and quality of life (EQ5D), patients with a confirmed diagnosis of CHF were prescribed medication with advice on titration and target doses. Trained CHF nurses gave Information on CHF and provided follow up.

RESULTS

Half (47%) of the referred patients had the diagnosis of CHF confirmed. Low NT-proBNP values (< 300 ng/l) provided a negative predictive value of 73%. Respiratory tract diseases were common differential diagnoses. At one year of follow-up, medication in the CHF group was 86% ACE-inhibitors/angiotensin receptor blockers, 61% ß-blocking agents, and 81% diuretics (P < 0.001 for the increase in ACE-inhibitors/angiotensin receptor blockers from baseline). NYHA class improved from baseline (median 2, range: 1-3) to one year (P < 0.05), whereas NT-proBNP (1491-1261 ng/l), and quality of life (EQ5D; 67-67) were unchanged.

CONCLUSION

A management programme to optimize quality of care for patients with suspected new onset CHF in primary care, with referral to a hospital-based specialist team, can be applied successfully.

Measurement of natriuretic peptides at the point of care in the emergency and ambulatory setting: current status and future perspectives

The measurement of natriuretic peptides (NPs), B-type NP or N-terminal pro-B-type NP, can be an important tool in the diagnosis of acute heart failure in patients presenting to an Emergency Department (ED) with acute dyspnea, according to international guidelines. Studies and subsequent meta-analyses are mixed on the absolute value of routine NP assessment of ED patients. However, levels of NPs are likely to be used also to guide treatment and to assess risk of adverse outcomes in other patients at risk of developing heart failure, including those with pulmonary embolism or diabetes, or receiving chemotherapy. Natriuretic peptide levels, like other biomarkers, can now be measured at the point of care (POC). We have reviewed the current status of NP measurement together with the potential contribution of POC measurement of NPs to clinical care delivery in the emergency and other settings. Several POC systems for measuring NP levels are now available: these produce test results within 15 minutes and appear sufficiently sensitive and robust to be used routinely in diagnostic evaluations. Point-of-care systems could be used to assess NP levels in the ED and community outpatient settings to monitor the risk of acute heart failure. Furthermore, the use of protocol-driven POC testing of NP within the time frame of a patient consultation in the ED may facilitate and accelerate the throughput and disposition of at-risk patients. Appropriately designed clinical trials will be needed to confirm these potential benefits. It is also important that processes of care delivery are redesigned to take full advantage of the faster turnaround times provided by POC technology.

PATHFAST NT-proBNP (N-terminal-pro B type natriuretic peptide): a multicenter evaluation of a new point-of-care assay

BACKGROUND

The biochemical determination of cardiac natriuretic peptides, primarily brain natriuretic peptide (BNP) and the amino-terminal fragment of its pro-hormone proBNP (NT-proBNP), are reliable tools for diagnosing cardiac disease, establishing prognosis and evaluating the effectiveness of treatment. These biomarkers have proven to be of particular value in the management of chronic and acute heart failure patients, and in the outpatient and the emergency setting.

METHODS

A multicenter evaluation was performed to assess the practicability, and the analytical and clinical performance of a new point-of-care testing (POCT) PATHFAST NT-proBNP assay. This is an immunochemiluminescent assay using two polyclonal antibodies in a sandwich test format, and performed with a PATHFAST automated analyzer.

RESULTS

The limit of detection (mean+3 SD of the signal of 20 replicates of the zero calibrator obtained in one run) was 0.535 ng/L. An imprecision study, performed in accordance with the CLSI protocol, showed coefficients of variation of 4.0%-6.4% (within-run imprecision), 0.0%-3.4% (between-run imprecision), 5.5%-7.2% (between-day imprecision), 7.6%-8.9% (total imprecision). The method was linear to 28,755 ng/L. Slopes and intercepts ranged from 0.89 to 0.90 and from 10.96 to 22.85, respectively when lithium-heparin plasma samples (n=100) were used to compare the assay under evaluation with the routine laboratory methods (Dimension RxL, Stratus CS). When testing matched samples (n=52), a significant difference was found between the 50th percentile NT-proBNP concentration in K(2)EDTA whole blood, K(2)EDTA plasma, lithium-heparin plasma and serum. No significant interference was observed for NT-proBNP in lipemic (tryglicerides up to 28.54 mmol/L), icteric (total and conjugated bilirubin up to 513 and 13 micromol/L, respectively) or hemolyzed (hemoglobin up to 13.50 g/L) samples. The NT-proBNP concentration in a group of 180 healthy donors was significantly influenced by age and gender. In a selected population of patients (n=56) with acute dyspnea admitted to the emergency department, a marked reduction in cardiac natriuretic peptide concentrations was observed in hospitalized patients suffering from heart failure who had a better prognosis compared with those with a poorer prognosis (NT-proBNP mean Delta change, % from -22 to -71 vs. +9 to -11).

CONCLUSIONS

The satisfactory analytical and clinical performance of the PATHFAST NT-proBNP assay, together with its excellent practicability, suggests that it would be a reliable tool in clinical practice, in the emergency setting for point-of-care testing, as well as in the central laboratory.

A high-affinity recombinant antibody permits rapid and sensitive direct detection of myeloperoxidase

Over the past 10 years, a growing field of research supporting the value of myeloperoxidase (MPO) as a prognostic indicator in acute cardiac pathophysiologies has emerged. The availability of a rapid and disposable MPO detection platform would enable research clinicians to more readily assess MPO indications for guiding therapy and also facilitate clinicians at the patient interface to readily adopt MPO testing and potentially drive more informed prognoses. Here we describe the isolation of a high-affinity avian MPO-specific recombinant antibody panel using phage display. Rapid isolation of a suitable single-chain variable fragment (scFv) antibody was facilitated using a surface plasmon resonance (SPR)-based "off-rate ranking" screening process. The selected scFv was then successfully incorporated into a rapid, simple, and sensitive one-step lateral flow immunoassay (LFIA) for the detection of MPO. This "one-step" feature of the developed assay was made possible by the scFv's strong affinity for MPO, obviating the need for sandwich signal enhancement steps. The assay's rapid performance was also further enhanced by exploiting the intrinsic enzymatic properties of MPO in its final detection. Use of the optimized LFIA facilitated the sensitive detection of MPO in MPO-depleted serum within clinically relevant reference ranges.