C-reactive protein: a new rapid assay for managing infectious disease in primary health care

C-reactive protein point-of-care testing in primary care-broader implementation needed to combat antimicrobial resistance

This study presents the perspective of an international group of experts, providing an overview of existing models and policies and guidance to facilitate a proper and sustainable implementation of C-reactive protein point-of-care testing (CRP POCT) to support antibiotic prescribing decisions for respiratory tract infections (RTIs) with the aim to tackle antimicrobial resistance (AMR). AMR threatens to render life-saving antibiotics ineffective and is already costing millions of lives and billions of Euros worldwide. AMR is strongly correlated with the volume of antibiotics used. Most antibiotics are prescribed in primary care, mostly for RTIs, and are often unnecessary. CRP POCT is an available tool and has been proven to safely and cost-effectively reduce antibiotic prescribing for RTIs in primary care. Though established in a few European countries during several years, it has still not been implemented in many European countries. Due to the complexity of inappropriate antibiotic prescribing behavior, a multifaceted approach is necessary to enable sustainable change. The effect is maximized with clear guidance, advanced communication training for primary care physicians, and delayed antibiotic prescribing strategies. CRP POCT should be included in professional guidelines and implemented together with complementary strategies. Adequate reimbursement needs to be provided, and high-quality, and primary care-friendly POCT organization and performance must be enabled. Data gathering, sharing, and discussion as incentivization for proper behaviors should be enabled. Public awareness should be increased, and healthcare professionals' awareness and understanding should be ensured. Impactful use is achieved when all stakeholders join forces to facilitate proper implementation.

Adoption of C-reactive protein point-of-care tests for the management of acute childhood infections in primary care in the Netherlands and England: a comparative health systems analysis

BACKGROUND

The use of point of care (POC) tests varies across Europe, but research into what drives this variability is lacking. Focusing on CRP POC tests, we aimed to understand what factors contribute to high versus low adoption of the tests, and also to explore whether they are used in children.

METHODS

We used a comparative qualitative case study approach to explore the implementation of CRP POC tests in the Netherlands and England. These countries were selected because although they have similar primary healthcare systems, the availability of CRP POC tests in General Practices is very different, being very high in the former and rare in the latter. The study design and analysis were informed by the non-adoption, abandonment, spread, scale-up and sustainability (NASSS) framework. Data were collected through a review of documents and interviews with stakeholders. Documents were identified through a scoping literature review, search of websites, and stakeholder recommendation. Stakeholders were selected purposively initially, and then by snowballing. Data were analysed thematically.

RESULTS

Sixty-five documents were reviewed and 21 interviews were conducted. The difference in the availability of CRP POC tests is mainly because of differences at the wider national context level. In the two countries, early adopters of the tests advocated for their implementation through the generation of robust evidence and by engaging with all relevant stakeholders. This led to the inclusion of CRP POC tests in clinical guidelines in both countries. In the Netherlands, this mandated their reimbursement in accordance with Dutch regulations. Moreover, the prevailing better integration of health services enabled operational support from laboratories to GP practices. In England, the funding constraints of the National Health Service and the prioritization of alternative and less expensive antimicrobial stewardship interventions prevented the development of a reimbursement scheme. In addition, the lack of integration between health services limits the operational support to GP practices. In both countries, the availability of CRP POC tests for the management of children is a by-product of the test being available for adults. The tests are less used in children mainly because of concerns regarding their accuracy in this age-group.

CONCLUSIONS

The engagement of early adopters combined with a more favourable and receptive macro level environment, including the role of clinical guidelines and their developers in determining which interventions are reimbursed and the operational support from laboratories to GP practices, led to the greater adoption of the tests in the Netherlands. In both countries, CRP POC tests, when available, are less used less in children. Organisations considering introducing POC tests into primary care settings need to consider how their implementation fits into the wider health system context to ensure achievable plans.

Impact of point-of-care C-reactive protein testing intervention on non-prescription dispensing of antibiotics for respiratory tract infections in private community pharmacies in Nigeria: a cluster randomized controlled trial

OBJECTIVES

To ascertain if access to C-reactive protein (CRP) test kits-and staff training on how to use them in respiratory tract infection (RTI) management-in private community pharmacies (PCPs) can reduce non-prescription antibiotic dispensing for RTI.

METHODS

A parallel cluster randomized controlled trial was conducted in Nigeria. The clusters-which were equally the participating units-were PCPs with blood testing experience. Stratified block randomization was done. PCPs were stratified by the baseline value of the primary outcome. PCPs were not blinded. The intervention PCPs were provided with CRP kits and trained to use them to make decisions regarding non-prescription antibiotic dispensing for RTI. The control PCPs received no intervention. The primary outcome was the non-prescription antibiotic dispensing rate for RTI. Data were collected by blinded simulated clients who visited each PCP 30 times before and after the intervention without prescriptions. Analyses were by intention-to-treat.

RESULTS

Twenty PCPs were randomized, 1:1. Ten PCPs were analyzed in each arm. Each PCP contributed 30 data points to the multiple imputation analysis where antibiotic dispensing decreased by 15.66% (209/300 [intervention] vs 256/300 [control]) in the adjusted analysis (odds ratio = 0·279, 95% confidence interval = 0.107-0.726; P-value = 0.0090) and 16% (208/300 [intervention] vs 256/300 [control]) in the crude analysis (odds ratio = 0.299, 95% confidence interval = 0.098-0.911; P-value = 0.034).

CONCLUSION

Access to CRP kits-and staff training on how to use them in RTI management-in PCPs reduced non-prescription antibiotic dispensing for RTI.

Introducing the C-reactive protein point-of-care test: A conversation analytic study of primary care consultations for respiratory tract infection

The C-reactive protein point-of-care test (CRP-POCT) can help distinguish between viral and bacterial infection and has been promoted as a strategy to improve antimicrobial stewardship. The test is widely used in Sweden. National guidelines advocate conservative use in primary care consultations with patients presenting with symptoms of respiratory tract infection (RTI). Previous research suggests low adherence to guidelines. We provide new insights into the communication surrounding the CRP-POCT by documenting how the decision to administer the test is interactionally motivated and organized in Swedish primary care. The data consists of video-recordings of RTI-consultations. A CRP-POCT was performed in nearly two thirds of the consultations and our study is focused on a subset where the test is ordered by a medical doctor. We find that doctors order the test during the transition from or after physical examination, a practice that aligns with national guidelines. Guidelines indicate that pathological findings from physical examination are warrants for ordering the test but we only found one example where this was communicated to the patient. A more prevalent pattern was that doctors ordered the CRP-POCT even though the outcome of the physical examination was assessed as normal. Our analyses of these show that doctors can provide the rationale for ordering the test in subtle ways and that failure to provide a rationale is treated as a noticeable absence. We also find that the CRP-POCT can be used to reconcile the contrast between the normal physical examination and the patient's problem presentation. Doctors can also order the test in ways that position the CRP-POCT as criterial for antibiotic prescription. Consultations where the patients described the symptoms as particularly severe and/or persistent were more likely to engender elaborate accounts than consultations where patients presented their symptoms as less problematic.

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.

Near-patient tests and the clinical gaze in decision-making of Swedish GPs not following current guidelines for sore throat - a qualitative interview study

Background

Excessive antibiotics use increases the risk of resistance. Previous studies have shown that the Centor score combined with Rapid Antigen Detection Test (RADT) for Group A Streptococci can reduce unnecessary antibiotic prescribing in patients with sore throat. According to the former Swedish guidelines RADT was recommended with 2–4 Centor criteria present and antibiotics were recommended if the test was positive. C- reactive protein (CRP) was not recommended for sore throats. Inappropriate use of RADT and CRP has been reported in several studies.

Methods

From a larger project 16 general practitioners (GPs) who stated management of sore throats not according to the guidelines were identified. Half-hour long semi-structured interviews were conducted. The topics were the management of sore throats and the use of near-patient tests. Qualitative content analysis was used.

Results

The use of the near-patient test interplayed with the clinical assessment and the perception that all infections caused by bacteria should be treated with antibiotics. The GPs expressed a belief that the clinical picture was sufficient for diagnosis in typical cases. RADT was not believed to be relevant since it detects only one bacterium, while CRP was considered as a reliable numerical measure of bacterial infection.

Conclusions

Inappropriate use of near-patient test can partly be understood as remnants of outdated knowledge. When new guidelines are introduced the differences between them and the former need to be discussed more explicitly.

Synovial IL-6 as inflammatory marker in periprosthetic joint infections

We analyzed serum and synovial biomarkers of 69 patients. 31 of them suffered from a periprosthetic joint infection (PJI) and 38 from aseptic arthralgia after total joint arthroplasty. We used Receiver-Operating-Characteristic-curves to calculate the Area-under-the-curve (AUC), cutoff-values, positive (+LR), negative (-LR) and interval-Likelihood-Ratios (iLR) for predicting a PJI. The most significant parameter was synovial interleukin-6 (IL-6) (cutoff-value ≥ 30,750 pg/ml, AUC = 0.959, SE = 90.0%, SP = 94.7%, +LR = 17.27), followed by synovial lactate (cutoff-value ≥ 8.3 mmol/l, AUC = 0.844, SE = 71.4%, SP=88.0%, +LR = 5.95), and synovial glucose (cutoff-value ≤ 44 mg/dl, AUC = 0.829, SE = 79.2%, SP = 78.6%, +LR = 3.69). IL-6 ≥ 30,750 pg/ml and lactate ≥ 10 mmol/l make a PJI very likely, IL-6 <10,000pg/ml or lactate <4.3 mmol/l makes a PJI very unlikely. If none of these thresholds are met, physicians should use the iLR of IL-6, glucose and lactate to estimate the likelihood of PJI.

Antibiotic prescribing and C-reactive protein testing for pulmonary infections in patients with intellectual disabilities

BACKGROUND

Excessive prescribing of antibiotics in patients with lower respiratory tract infections (LRTIs) is common in the general population. Due to communication difficulties, it is hypothesised that prescriptions are even more commonplace in the primary care of individuals with intellectual disabilities. Point-of-care C-reactive protein (POC-CRP) testing might lead to more efficient prescribing of antibiotics.

AIM

To evaluate the effect of POC-CRP testing on antibiotic prescriptions for LRTIs by physicians specialising in the care of individuals with intellectual disabilities.

DESIGN AND SETTING

A prospective case-control study in four care centres for individuals with intellectual disabilities in The Netherlands.

METHOD

Between 27 October 2010 and 27 October 2011, a prospective efficiency study was performed with a base population of 1472 individuals. This population consisted of 882 individuals in whom POC-CRP tests were used and a control group (n = 590) in whom no POC-CRP test was performed.

RESULTS

Of the 48 patients in the control group who were diagnosed as having an LRTI, 43 (90%) received antibiotics, compared with 59 out of the 144 patients (41%) in the case group (OR = 12.0; 95% CI = 4.1-35.3). No significant differences in outcome were found between both groups during a follow-up period of 1 month.

CONCLUSION

This study shows that the use of POC-CRP testing in patients with intellectual disabilities and LRTIs can lead to a significant reduction in antibiotic prescriptions, with no significant differences in outcome during follow-up.

Bacterial superinfection in upper respiratory tract infections estimated by increases in CRP values: a diagnostic follow-up in primary care

OBJECTIVE

The aim of this study was to estimate the rate of bacterial superinfection in patients with URTI by using on-site determination of C-reactive protein (CRP).

DESIGN

A prospective cohort study.

SETTING

A total of 30 primary care practices.

SUBJECTS

Patients with URTI.

INTERVENTION

The CRP value was determined at the first consultation and at a follow-up within 3-5 days. CRP values of 30 units (mg) or higher were considered to be an indication of bacterial involvement.

MAIN OUTCOME MEASURES

CRP values during follow-up and duration of illness.

RESULTS

Among the 506 patients included, 73.1% exhibited a CRP value below the defined limit at their first visit and were considered to suffer from URTI of viral origin. The rate of subsequent bacterial superinfection was 8.1%. Compared with patients suffering from URTI of bacterial or viral origin the duration of illness in patients with bacterial superinfection was significantly longer.

CONCLUSION

During follow-up of patients with URTI, the prevalence of bacterial superinfection detected by using a near patient CRP determination is surprisingly low. This result should help to reduce the prescription rate of antibiotics in primary care.

Role of infection and antimicrobial therapy in acute exacerbations of chronic obstructive pulmonary disease

Over the past several years, the significance of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) in patients with chronic airflow obstruction has become increasingly apparent due to the impact these episodes have on the natural history of disease. It is now known that frequent AECOPD can adversely affect a patient's health-related quality of life and short- and long-term pulmonary function. The economic burden of these episodes is also substantial. AECOPDs represent a local and systemic inflammatory response to both infectious and noninfectious stimuli, but the majority of episodes are likely related to bacterial or viral pathogens. Patients with purulent sputum and multiple symptoms are the most likely to benefit from treatment with antibiotics. Antibiotic choice should be tailored to the individual patient, taking into account the severity of the episode and host factors which might increase the likelihood of treatment failure. Current evidence suggests that therapeutic goals not only include resolution of the acute episode, but also prolonging the time to the next event. In the future, preventing exacerbations will likely become increasingly accepted as an additional therapeutic goal in chronic obstructive pulmonary disease patients.

Economic consequence of immediate testing for C-reactive protein and leukocyte count in new outpatients with acute infection

BACKGROUND

There have been few well-designed studies that assess the cost-effectiveness of near-patient immediate testing.

METHODS

We analyzed the economic outcome of immediate testing for C-reactive protein (CRP) and white blood cell count (WBC) in 305 new outpatients with acute infections. Patients were randomized into two groups: 147 patients were tested immediately for CRP and WBC before the physician's initial consultation (advance testing), and 154 patients were not subjected to advance testing. The subsequent prescribing decision and the drug/testing/personnel costs were compared between the groups.

RESULTS

In the advance-testing group, the initial consultation was followed by a total of 84 prescriptions of oral antibiotics, against 158 in the other group. Comparing the total costs of oral and parenteral antibiotics between the two groups, a 30% reduction was achieved with advance testing ( yen105,830 vs. yen151,102). However, the savings were largely offset by frequent prescription of newer, expensive influenza neuraminidase inhibitors. Advance testing also significantly reduced additional laboratory use. More frequent urgent testing increased personnel costs in the non-advance-testing group. Overall, total cost was somewhat higher in the advance-testing group ( yen1,028,827 vs. yen984,105).

CONCLUSIONS

The cost per antibiotic prescription reduced with advance testing was yen604 (approximately 5.8 US dollars) in our clinical setting. Judicious use of antivirals and introduction of a simple CRP test kit would improve cost-effectiveness.

Diagnostic value of C reactive protein in infections of the lower respiratory tract: systematic review

OBJECTIVES

To evaluate the diagnostic accuracy of C reactive protein in detecting radiologically proved pneumonia and to evaluate how well it can discriminate between bacterial and viral infections of the lower respiratory tract.

DATA SOURCES

Medline and Embase (January 1966 to April 2004), with reference checking.

STUDY SELECTION

We included articles comparing C reactive protein with a chest radiograph or with microbiological work-up as a reference test. Two authors independently assessed methodological items.

RESULTS

None of the studies met all validity criteria. Six studies used an infiltrate on chest radiograph as reference test. Sensitivities ranged from 10% to 98%, specificities from 44% to 99%. For adults, the relation of C reactive protein with an infiltrate (in a subgroup analysis of five studies) showed an area under the curve of 0.80 (95% confidence interval 0.75 to 0.85). In 12 studies, the relation of C reactive protein with a bacterial aetiology of infection of the lower respiratory tract was studied. Sensitivities ranged from 8% to 99%, specificities from 27% to 95%. These data were epidemiologically and statistically heterogeneous, so overall outcomes could not be calculated.

CONCLUSION

Testing for C reactive protein is neither sufficiently sensitive to rule out nor sufficiently specific to rule in an infiltrate on chest radiograph and bacterial aetiology of lower respiratory tract infection. The methodological quality of the diagnostic studies is generally poor. The evidence not consistently and sufficiently supports a wide introduction of C reactive protein as a rapid test to guide antibiotics prescription.

Sensitive noninvasive marker for the diagnosis of probable bacterial or viral infection

Urinary trypsin inhibitor (uTi) is a product of elastase-mediated degradation of interleukin-alpha-inhibitor (I-alpha-I). Its activity increases in the urine of patients with a malignancy, inflammation, or infection, or in late pregnancy. The objective of this study was to compare the sensitivity of uTi in urine with that of serum quantitative C-reactive protein (CRP) for diagnosing infection, as indicated by white cell response and clinical assessment. Ninety controls and 171 patients with various systemic infections were enrolled. We measured uTi enzymatically on a Cobas Fara (Roche Diagnostics). Patients were separated into bacterial, probable bacterial, viral, or probable viral groups based on the results of a complete blood count with differential (CBC), urinalysis (UA), and clinical assessment. In the bacterial (n=70) and control (n=90) groups, the uTi values (mean+/-SE) were 25.3+/-3.1 mg/L and 2.8+/-0.8 mg/L, respectively. uTi (at 2.7 mg/L) had a diagnostic sensitivity of 91% and specificity of 82% (AUC=0.889), whereas CRP (at a cutoff of 10 mg/L) had a sensitivity and specificity of 82% and 96%, respectively (AUC=0.921). As a marker of infection (positive in both bacterial and viral groups), uTi had a sensitivity of 91% (AUC=0.884) vs. 89% (AUC=0.828) for CRP. Our data indicate that uTi has sufficient clinical sensitivity for screening systemic infections, and may have diagnostic value as a noninvasive test.

Clinical items not helpful in differentiating viral from bacterial lower respiratory tract infections in general practice

OBJECTIVE

Incorrect and unnecessary antibiotic prescribing enhancing bacterial resistance rates might be reduced if viral and bacterial lower respiratory tract infections (LRTI) could be differentiated clinically. Whether this is possible is often doubted but has rarely been studied in general practice.

STUDY DESIGN AND SETTING

This was an observational cohort study in 15 general practice surgeries in the Netherlands.

RESULTS

Etiologic diagnoses were obtained in 112 of 234 patients with complete data (48%). Viral pathogens were found as often as bacterial pathogens. Haemophilus (para-) influenzae was most frequently found. None of the symptoms and signs correlated statistically significantly with viral or bacterial LRTI. Erythrocyte sedimentation rate >50 (odds ratio [OR] 2.3-3.3) and C-reactive protein (CRP) >20 (OR 2.1-4.6) were independent predictors for viral LRTI and bacterial LRTI when compared with microbiologically unexplained LRTI.

CONCLUSION

Extensive history-taking and physical examination did not provide items that predict viral or bacterial LRTI in adult patients in daily general practice. We could not confirm CRP to differentiate between viral and bacterial LRTI.

Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis

A meta-analysis was performed to evaluate the accuracy of determination of procalcitonin (PCT) and C-reactive protein (CRP) levels for the diagnosis of bacterial infection. The analysis included published studies that evaluated these markers for the diagnosis of bacterial infections in hospitalized patients. PCT level was more sensitive (88% [95% confidence interval [CI], 80%-93%] vs. 75% [95% CI, 62%-84%]) and more specific (81% [95% CI, 67%-90%] vs. 67% [95% CI, 56%-77%]) than CRP level for differentiating bacterial from noninfective causes of inflammation. The Q value for PCT markers was higher (0.82 vs. 0.73). The sensitivity for differentiating bacterial from viral infections was also higher for PCT markers (92% [95% CI, 86%-95%] vs. 86% [95% CI, 65%-95%]); the specificities were comparable (73% [95% CI, 42%-91%] vs. 70% [95% CI, 19%-96%]). The Q value was higher for PCT markers (0.89 vs. 0.83). PCT markers also had a higher positive likelihood ratio and lower negative likelihood ratio than did CRP markers in both groups. On the basis of this analysis, the diagnostic accuracy of PCT markers was higher than that of CRP markers among patients hospitalized for suspected bacterial infections.

The use of CRP tests in patients with respiratory tract infections in primary care in Sweden can be questioned

A diagnosis-antibiotic prescribing study was performed in 5 counties in Sweden during 1 week in November in 2000 and 2002 respectively. As a part of the study, the use and results of C-reactive protein (CRP) tests in relation to duration of symptoms and antibiotic prescribing in 6778 patients assigned a diagnosis of respiratory tract infections were analysed. In almost half (42%) of the patients, a CRP test was performed. The majority of CRP tests (69%) were performed in patients assigned diagnosis upper respiratory tract infection, where the test is not recommended. Overall, there was a minor decrease in antibiotic prescribing when CRP was used (41%), in comparison to 44% of the patients where no CRP was performed (p < 0.01). Patients assigned diagnoses implying a bacterial aetiology were prescribed antibiotics irrespective of result of CRP or length of symptoms before consultation. For patients assigned viral diagnoses, antibiotic prescribing increased with increasing duration of symptoms and increasing value of CRP. The use of CRP decreased antibiotic prescribing in patients assigned to viral diagnoses and with longstanding symptoms (p < 0.001). However, 59% of the patients assigned viral diagnoses with CRP > or = 25 received antibiotics, which seems to indicate a misinterpretation of CRP and a non-optimal use of antibiotics.

Antimicrobial guidelines for the treatment of acute bacterial rhinosinusitis in immunocompetent children

Acute rhinosinusitis represents a condition for which educational efforts could help minimize the inappropriate use of antibiotics, particularly for children. The majority of acute rhinosinusitis cases are of viral etiology and thus, are self limiting. Although bacterial infection complicates a small number of cases, the lack of accessibility to the sinus, the limitations of diagnostic modalities and the lack of specificity among signs and symptoms often make it difficult to determine when bacterial infection occurs. Furthermore, antimicrobial resistance among the pathogens that frequently cause bacterial infection complicates the election of empiric therapy. The Sinus and Allergy Health Partnership recently developed and published antimicrobial guidelines to provide practitioners in the US with recommendations for the diagnosis and treatment of acute bacterial rhinosinusitis. The purpose of this paper is to review the rationale behind the development of these guidelines and how they apply to the management of acute bacterial rhinosinusitis in children.

Systematic review of near patient test evaluations in primary care

OBJECTIVE

To identify and qualitatively synthesise the findings from all studies that have examined the performance and effect of near patient tests in the primary care setting.

DESIGN

Systematic review of published and unpublished research 1986-99.

MAIN OUTCOME MEASURES

Test performance characteristics, measures of effect on clinical practice or patient outcome.

RESULTS

101 relevant publications were identified. The general quality of these papers was low, and consequently only 32 papers were assessed in detail. Although these papers gave some indication of the value of near patient testing in areas such as anticoagulation monitoring and group A beta haemolytic streptococcus testing, the research raised many more questions than it answered. Almost no reports were found of unbiased assessment of the effect of near patient tests in primary care on patient outcomes, organisational outcomes, or cost.

CONCLUSIONS

Available research provides little evidence to guide the expansion of use of near patient testing in primary care. Further research is needed in areas of clinical practice where near patient tests might be most beneficial.

Near-Patient Test for C-Reactive Protein in General Practice: Assessment of Clinical, Organizational, and Economic Outcomes

Background: The benefits of near-patient, point-of-care tests have not been fully examined. We have assessed the clinical, organizational, and economic outcomes of implementing a near-patient test for C-reactive protein (CRP) in general practice.

Methods: In a randomized crossover trial during intervention periods, general practitioners (GPs) were allowed to measure CRP within 3 min, using NycoCard® CRP. During control periods, they had to mail blood samples for CRP measurements to the hospital laboratory and received test results 24–48 h later. Twenty-nine general practice clinics participated (64 GPs), and 1853 patients were included in the study. Results were evaluated at both the level of participating GPs and the level of included patients.

Results: For participating GPs, the overall use of erythrocyte sedimentation rates (ESRs) decreased by 8% (95% confidence interval, 1–14%) during intervention periods, and the number of blood samples mailed to the hospital laboratory decreased by 6% (1–10%). No reduction in the prescription of antibiotics was seen. The proportion of study patients having a follow-up telephone consultation was reduced from 63% to 53% (P = 0.0001), and patients with CRP concentrations &gt;50 mg/L had their antibiotic treatments started earlier when CRP was measured in general practices (P = 0.0161).

Conclusion: The implementation of the near-patient CRP test was cost-effective mainly on the basis of a reduction in the use of services from the hospital laboratory by GPs. If the implementation is followed by education and clinical guidelines, opportunities exist for additional reduction in the use of ESR and for a more appropriate use of antibiotics.

Evaluation of a near-patient test for C-reactive protein used in daily routine in primary healthcare by use of difference plots

We have assessed the technical performance and robustness of NycoCard® CRP Whole Blood, a near-patient test for C-reactive protein (CRP), when used in realistic daily routine situations in general practice clinics (GPC). Thirteen GPCs participated, five of them with technician staff. From 898 patients, split-sample measurements for CRP were made. Results from GPCs were compared with results from a turbidimetric laboratory method, traceable to international reference preparations (IFCC CRM 470). Results were evaluated in difference plots where the expected distribution, due to an estimated analytical variation, was compared with measured differences. Of all difference points, 91.5% (n = 819) were within a 95% prediction interval based on the imprecision of both methods. Mean bias (95% confidence interval) was −0.3 mg/L (−0.9 to 0.3). No differences in analytic quality were found between GPCs with technician staffs and GPCs without, and between test results obtained within the first and second week, compared with the rest of the study period. We find the test as good when used in GPCs as could be expected from laboratory testing, and consequently robust, which is a necessity for use in routine situations in general practice. General application of difference plots in test evaluations are discussed in detail.

C-reactive protein in general practice--how commonly is it used and why?

OBJECTIVE

C-reactive protein (CRP) is a well-known diagnostic tool in general practice. The scope of this study was to assess how frequently CRP is used by general practitioners and to evaluate the reasons for using it.

DESIGN

A retrospective part based on data from a laboratory database system, and a prospective part with a questionnaire-based registration.

SETTING

30 general practice clinics in the catchment area of Vejle County Central Hospital.

SUBJECTS

Retrospectively, all patients from general practice serviced by the laboratory for one year. Prospectively, 1190 patients from whom a blood sample was taken for CRP-measurement during a 2 month study period.

MAIN OUTCOME MEASURES

The frequency of using CRP and the reason requesting it; A) diagnosing a new disease, B) monitoring a well-known disease, or C) "screening". Furthermore; 1) infections, 2) chronic inflammatory disease, 3) malignant disease, or 4) others.

RESULTS

CRP-measurements were ordered in 3.7% of all consultations in general practice and for 34.1% of all patients whose blood sample was analysed at the central laboratory. The use of CRP was as follows: A-1: 28.6%, A-2: 6.7%, A-3,4: 9.3%, B-1: 8.2%, B-2: 12.4%, B-3,4: 6.5%, C-1: 5.7%, C-2: 3.2%, C-3: 3.5% and C-4: 15.2%. Diagnosing a new (infectious) disease was the most frequent single reason for CRP-measurement. There was major interpractice variation.

CONCLUSIONS

CRP is frequently used in general practice, mostly (65.4%) in the field of infections and chronic inflammatory diseases. Because of major interpractice variation, the most correct way of using CRP should be evaluated and guidelines should be provided.

Predicting acute maxillary sinusitis in a general practice population

OBJECTIVE

To evaluate the diagnostic value of symptoms, signs, erythrocyte sedimentation rate, and C reactive protein for acute maxillary sinusitis.

DESIGN

Prospective cohort study.

SETTING

Danish general practice in cooperation with the otorhinolaryngology and neuroradiology department at Aalborg County Hospital.

SUBJECTS

174 patients aged 18-65 years who were suspected by the general practitioner of having acute maxillary sinusitis.

MAIN OUTCOME MEASURE

The independent association of symptoms, signs, erythrocyte sedimentation rate, and concentration of C reactive protein in patients with acute maxillary sinusitis defined as purulent or mucopurulent antral aspirate.

RESULTS

Only raised erythrocyte sedimentation rate (P = 0.01) and raised C reactive protein (P = 0.007) were found to be independently associated with a diagnosis of acute maxillary sinusitis. The combination of the two variables had a sensitivity of 0.82 and a specificity of 0.57.

CONCLUSION

Erythrocyte sedimentation rate and C reactive protein are useful diagnostic criteria for acute maxillary sinusitis.

Colloidal gold conjugated monoclonal antibodies, studied in the BIAcore biosensor and in the Nycocard immunoassay format

Interactions between immobilized capture monoclonal antibodies (mAbs), analyte molecules and colloidal gold conjugated second monoclonal antibodies have been investigated in the BIAcore biosensor and in the Nycocard immunoassay format. This report focuses on six monoclonal antibodies against human heart myoglobin, although, results with other antigens are also discussed. The BIAcore was used to screen monoclonal antibodies as antigen capture reagents, and for their function as colloidal gold conjugated second antibodies in the Nycocard. Some antibodies with low affinity caused by a rapid antigen dissociation rate, showed high affinity kinetics when used unlabelled or as gold conjugated detector reagents. One gold conjugated mAb with excellent properties in the Nycocard, showed double binding to one epitope, when tested in the BIAcore. The real time visualization of association and dissociation rates was a unique tool in the elucidation of antigen-antibody interactions. Our study confirmed that good antibody candidates selected with the BIAcore must always be tested in their actual conjugation situation before final optimization.

Diagnostic value of C-reactive protein measurement does not justify replacement of the erythrocyte sedimentation rate in daily general practice

The purpose of this paper was to establish the diagnostic value of the C-reactive protein measurement (CRP) in patients attending their general practitioner (GP) with a new complaint for which the GP considers determination of the erythrocyte sedimentation rate (ESR) to be indicated. During 4 successive months in 1992, 11 GPs in four general practice centres in the Netherlands identified patients indicated for the erythrocyte sedimentation rate. ESR and CRP were determined at the local hospital laboratory. One year later, an independent GP established the follow-up diagnoses. By comparing the test results with the follow-up diagnoses, using logistic regression analysis and Receiver Operating Characteristic curves, sensitivities, specificities, predictive values and odds ratios were established. In 396 patients the prevalence of inflammatory diseases and malignancies ('pathology') was found to be 26% in males and 15% in females. Both ESR and CRP were valuable in discriminating pathology from harmless, often self-limiting diseases. The optimal upper limits of reference values ('cut-off points') for ESR were found to be 31 mm in both males and females. At these cut-off points, the diagnostic gains from positive and negative test results (positive predictive value minus prevalence, and negative predictive value minus 100% minus prevalence) were 45% and 4% for males and 30% and 2% for females. The optimal cut-off point for CRP was found at 15 mg L-1 in males and 34 mg L-1 in females. The diagnostic gain from positive and negative test results were 18% and 9% in males and 25% and 4% in females.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of C-reactive protein and the erythrocyte sedimentation rate in general practice

OBJECTIVE

To evaluate the NycoCard:::CRP test (Nycomed A/S, Oslo, Norway) in relation to ESR in consecutive patients in general practice. NycoCard:::CRP test was also compared with a reference method for CRP quantitation.

DESIGN

C-reactive protein and ESR were simultaneously measured in 607 consecutive patients at four community health centres.

SETTING

Four community health centres in southern Sweden.

RESULTS

We obtained consistent results in 71% of the cases. In 20% CRP was increased more than ESR, while ESR was increased more than CRP in 9%. CRP was increased in 16% while ESR was below the upper reference limit for age and sex. On the other hand ESR was increased while CRP was below 10 mg/l in five % of the patients. In most of the cases where there was a discrepancy- for example, in infectious diseases-the CRP results were more clear-cut. Using the NycoCard test the CRP concentration can be measured directly in a whole blood sample with the result available within minutes. Comparison of the NycoCard:::CRP test with the reference method for CRP quantitation showed good agreement.

CONCLUSION

In clinical situations with suspected inflammatory diseases, the CRP test appears often to yield more useful results than the ESR. The NycoCard:::CRP test is suitable for use in general practice.

The erythrocyte sedimentation rate in general practice: clinical assessment based on case histories

Thirteen case histories were mailed to 273 general practitioners to study the clinical assessment of the ESR. Participants were asked to state their reference limits for the ESR, as well as action values for the ESR in several clinical situations typical of primary care. The action value should represent the minimal ESR change from a given value necessary to initiate some kind of action towards the patient. The response rate was 76%. In most case histories, half the general practitioners reacted on an ESR change of 10 mm h-1 or less, which is usually due to analytical and biological variation, thus underlining the need for good analytical quality. In general the response was of the same magnitude irrespective of type of case history, i.e. whether the ESR was used in case finding, in diagnosis, or in follow-up. Estimation of the reference limit displayed considerable variation, and knowledge of a previous 'normal' ESR was of minor clinical importance. Furthermore, we found substantial variation regarding the change in ESR necessary to take action in different clinical situations. In principle, for many general practitioners the action value increased as the given ESR increased whereas others reacted on a constant change in ESR, or the change necessary to take action depended on the clinical situation. We conclude that both the different assessments as to the clinical significance of the ESR, and the unawareness of the significance of analytical and biological variation indicate that guidelines for rational use are needed.

Does near-to-patient testing contribute to the diagnosis of streptococcal pharyngitis in adults?

OBJECTIVE

To asses the efficacy of near-to-patient laboratory testing in diagnosing group A beta haemolytic streptococci throat infection in adults, alone and in conjunction with the doctor's clinical judgement.

SETTING AND SUBJECTS

174 primary care patients with a sore throat, of which 59 (34%) were identified as having group A streptococci.

MAIN OUTCOME MEASURES

The erythrocyte sedimentation rate, leucocyte count, and C-reactive protein, and a specific streptococcal immunological assay were evaluated separately and in conjunction with the doctor's clinical diagnosis. The presence of GAS throat infection, the reference standard, was defined as those patients presenting with a chief complaint of sore throat and having a positive GAS culture or a four-fold or more increase or fall of AST or ADNase B serum levels during a four-week observation period.

RESULTS

The discriminatory ability of the sedimentation rate was not satisfactory and added little useful clinical information. Leucocytes and C-reactive protein both yielded clinically significant information and had similar test characteristics. The immunological test had the best characteristics of the tests evaluated.

CONCLUSION

Near-to-patient testing, except the erythrocyte sedimentation rate, may, in addition to the clinical evaluation, contribute to the differential diagnosis of streptococcal pharyngitis in adults.

Reliability of C-reactive protein measurement in general practice in The Netherlands

The aim of this study was to compare the reliability of the whole blood NycoCard C-reactive protein measurement (CRP) with the erythrocyte sedimentation rate (ESR) in four general practice centres (GPCs) in The Netherlands with 443 patients indicated for ESR. During 4 successive months in 1992 NycoCard CRP was measured in capillary (whole) blood at the GPC. A venous blood sample was then transported to the local hospital laboratory in order to determine CRP turbidimetrically in plasma. Westergren's ESR was measured at the GPC and at the laboratory. The dichotomized CRP values measured at the GPCs corresponded with the laboratory values in 88% of the cases. Kappa was 65% (p < 0.00001). Using a 20 mm cut-off point, ESR values measured at the GPCs and the laboratory corresponded in 96% of cases (Kappa = 90%, p < 0.00001). Interpractice variabilities and learning effects did not influence the results. 'False normal' rates for CRP and ESR were 8% and 1%; 'false elevated' rates were 28% and 12% respectively. The reliability of the NycoCard CRP measurement in whole blood disappointed. In particular the 'false elevated' rate is unacceptably high for daily general practice. The background of the poor reliability remains unclear.

Epitope mapping and binding kinetics of monoclonal antibodies studied by real time biospecific interaction analysis using surface plasmon resonance

The interaction between human heart myoglobin and ten specific monoclonal antibodies was investigated with a new biosensor technology, real time biospecific interaction analysis (RT BIA), using surface plasmon resonance. Analysis of association and dissociation kinetics was monitored in real time, with unlabelled reactants. Antibody isotyping was rapid and simple. Epitope mapping with RT BIA confirmed, with substantial time saving, the sum of results obtained in conventional labelled systems. Monoclonal antibodies with four different epitope specificities and optimal binding function were selected for a myoglobin sandwich assay with enhanced sensitivity. BIAcore can be used directly as a diagnostic tool, or as an analytical tool in immunoassay development.

Rapid C-reactive protein (CRP) measurements in the diagnosis of acute appendicitis

C-reactive protein (CRP) has been measured in plasma of patients with acute appendicitis and in controls without appendicitis to test the accuracy and diagnostic performance of a new rapid test kit for CRP (NycoCard CRP). The values obtained for CRP by the rapid test correlated well (Rs = 0.92) with the reference method for measuring CRP. The sensitivity, specificity and predictive values were calculated at different cut-off values. At values > 10 mg l-1 a sensitivity of 58% and a negative predictive value of 72% were found. Higher values of sensitivity were observed for men than for women, 69% and 44% respectively. Patients with acute appendicitis who had had symptoms for more than 24 h, had elevated CRP values (cut-off > 10 mg l-1) in more than 80% of cases. Our study shows that the rapid CRP test and the reference CRP test gave an almost identical result.