889. Another Respiratory Culture Nudge Improves Pneumonia Prescribing

Background

Nudging with purposeful, directed comments to microbiology results appears to improve antibiotic prescribing. The study objective was to assess prescribing before and after a β-lactamase interpretative comment for Haemophilus influenzae and Moraxella catarrhalis lower respiratory tract infections (LRTI).

Methods

IRB approved, quasi-experiment. Included: hospitalized adults prescribed antibiotics for H. influenzae or M. catarrhalis LRTI from 8/20/17-3/19/19 (pre-group) and 3/20/19-8/20/21 (post-group). Excluded: non-LRTI, polymicrobial infections, antibiotic prophylaxis, IgE-mediated β-lactam allergy. Intervention- automated comment for β-lactamase negative: “this organism is predictably susceptible to ampicillin or amoxicillin”; β-lactamase positive: “this organism is predictably susceptible to ampicillin-sulbactam or amoxicillin-clavulanate”. Primary endpoint: optimal de-escalation, defined as ampicillin, amoxicillin or aminopenicillins for β-lactamase negative; amoxicillin/clavulanate or ampicillin/sulbactam for β-lactamase positive. Secondary endpoints: clinical success, antibiotic duration, time to de-escalation. Sample size: 200 calculated for 30% difference in de-escalation, α=0.05, β=0.2.

Results

Enrolled 100 pre- and 101 post. 61% vs. 64% male; 63% vs. 73% community-acquired pneumonia; 20% vs. 15% hospital acquired pneumonia; 17% vs. 12% ventilator associated pneumonia; 81% vs. 77% H. influenzae; 46% vs. 52% β-lactamase positive; 4% vs. 7% non-IgE β-lactam allergy, respectively. Optimal de-escalation: 19 (19%) pre-, 51 (51%) post- (p< 0.001). After adjustment, post-group associated with 5-fold increased odds of optimal de-escalation (Table 1). Secondary endpoints pre and post: median (IQR) duration 7 (6, 8) and 7 days (6, 10); median time to de-escalation: 1 (0, 2) and 0 (0, 1) days; clinical success: 79 (79%) and 81 (80%).

Conclusion

An automated, β-lactamase nudge was associated with a reduction in definitive broad-spectrum antibiotics. Stewardship programs should continue to evaluate persuasive comments as an effective and efficient intervention.

Disclosures

All Authors: No reported disclosures.

Pharmacist-Driven Transitions of Care Practice Model for Prescribing Oral Antimicrobials at Hospital Discharge

IMPORTANCE

Although prescribers face numerous patient-centered challenges during transitions of care (TOC) at hospital discharge, prolonged duration of antimicrobial therapy for common infections remains problematic, and resources are needed for antimicrobial stewardship throughout this period.

OBJECTIVE

To evaluate a pharmacist-driven intervention designed to improve selection and duration of oral antimicrobial therapy prescribed at hospital discharge for common infections.

DESIGN, SETTING, AND PARTICIPANTS

This quality improvement study used a nonrandomized stepped-wedge design with 3 study phases from September 1, 2018, to August 31, 2019. Seventeen distinct medicine, surgery, and specialty units from a health system in Southeast Michigan participated, including 1 academic tertiary hospital and 4 community hospitals. Hospitalized adults who had urinary, respiratory, skin and/or soft tissue, and intra-abdominal infections and were prescribed antimicrobials at discharge were included in the analysis. Data were analyzed from February 18, 2020, to February 28, 2022.

INTERVENTIONS

Clinical pharmacists engaged in a new standard of care for antimicrobial stewardship practices during TOC by identifying patients to be discharged with a prescription for oral antimicrobials and collaborating with primary teams to prescribe optimal therapy. Academic and community hospitals used both antimicrobial stewardship and clinical pharmacists in a multidisciplinary rounding model to discuss, document, and facilitate order entry of the antimicrobial prescription at discharge.

MAIN OUTCOMES AND MEASURES

The primary end point was frequency of optimized antimicrobial prescription at discharge. Health system guidelines developed from national guidelines and best practices for short-course therapies were used to evaluate optimal therapy.

RESULTS

A total of 800 patients prescribed oral antimicrobials at hospital discharge were included in the analysis (441 women [55.1%]; mean [SD] age, 66.8 [17.3] years): 400 in the preintervention period and 400 in the postintervention period. The most common diagnoses were pneumonia (264 [33.0%]), upper respiratory tract infection and/or acute exacerbation of chronic obstructive pulmonary disease (214 [26.8%]), and urinary tract infection (203 [25.4%]). Patients in the postintervention group were more likely to have an optimal antimicrobial prescription (time-adjusted generalized estimating equation odds ratio, 5.63 [95% CI, 3.69-8.60]). The absolute increase in optimal prescribing in the postintervention group was consistent in both academic (37.4% [95% CI, 27.5%-46.7%]) and community (43.2% [95% CI, 32.4%-52.8%]) TOC models. There were no differences in clinical resolution or mortality. Fewer severe antimicrobial-related adverse effects (time-adjusted generalized estimating equation odds ratio, 0.40 [95% CI, 0.18-0.88]) were identified in the postintervention (13 [3.2%]) compared with the preintervention (36 [9.0%]) groups.

CONCLUSIONS AND RELEVANCE

The findings of this quality improvement study suggest that targeted antimicrobial stewardship interventions during TOC were associated with increased optimal, guideline-concordant antimicrobial prescriptions at discharge.

225. Antimicrobial Stewardship Program Interventions Targeting Intravenous Vancomycin Use at a Community Hospital Improves Prescribing and Safety

Background

Methods

Results

Conclusion

Disclosures

Communicating Microbiology Results. It’s Not Just What You Say, But How You Say It

Background

Gaps in microbiology communication can lead to suboptimal antibiotic prescribing. In May 2016, our laboratory modified reporting of respiratory cultures growing commensal flora only to specify “no methicillin-resistant Staphylococcus aureus/MRSA or Pseudomonas aeruginosa” (PA). The purpose of this study was to compare MRSA and PA antibiotic therapy utilization before and after the change.

Methods

IRB approved, quasi-experiment at four hospitals with an antimicrobial stewardship program. Dates: August 1, 2015–January 31, 2016 and August 1, 2016–January 31, 2017. Included: ≥18 years, commensal flora only respiratory culture, empiric MRSA and PA antibiotic for treatment of lower respiratory infection. Excluded: non-respiratory infection. Primary outcome: MRSA or PA therapy de-escalated. Secondary outcomes: time to culture result, MRSA and PA antibiotic days of therapy, length of stay. Safety outcomes: acute kidney injury (AKI), C. difficile (CDI), subsequent multi-drug-resistant organism (MDRO), in-hospital all-cause mortality.

Results

Two hundred and ten patients included, 105 per group. Median age 64 and 61 years, male sex 52% and 56% in pre- and post-group, respectively. Empiric antibiotics, pre vs. post: vancomycin 94% vs. 95%; cefepime 66% vs. 36%; piperacillin–tazobactam 10% vs. 46%. MRSA or PA antibiotics de-escalated: 39% pre and 73% post (P < 0.001). See Table 1 for variables associated with antibiotic de-escalation. Days of therapy: 7 vs. 5 days (P < 0.001). AKI 31% vs. 14% (P = 0.003). Eight subsequent MDRO in pre and one in post (P = 0.035). No differences: time to culture result, length of stay, mortality, CDI.

Conclusion

Improved microbiology communication to assist prescriber interpretation of commensal respiratory flora was associated with a reduction in the proportion of patients that received antibiotics targeting MRSA and PA.

Disclosures

S. Davis, Merck: Received grant through college that I’m faculty for, Grant recipient; Allergan: Speaker’s Bureau, Consulting fee; Allergan: Consultant and Scientific Advisor, Consulting fee; Medicines Company: Consultant and Scientific Advisor, Consulting fee; Zavante: Consultant and Scientific Advisor, Consulting fee.

Cost-effectiveness of fondaparinux versus enoxaparin in non-ST-elevation acute coronary syndrome in Canada (OASIS-5)

Background

Acute coronary syndrome (ACS) refers to a spectrum of life-threatening cardiac diseases usually due to coronary artery plaque rupture, subsequent thrombin generation plaque activation and thrombus formation. To date, no economic analyses have been published about the use of fondaparinux in NSTE-ACS patients in Canada. The purpose of our study is to estimate the lifetime cost-effectiveness of fondaparinux compared to enoxaparin for non-ST-elevation acute coronary syndrome (NSTE-ACS) patients in a Canadian hospital setting.

Methods

As an extension of a previous published economic analysis for US patients, an event-based decision analytic model was constructed using clinical and resource use data from OASIS-5, a randomized trial of 20,078 patients from 41 countries. A public payer perspective in the hospital setting was adopted. Resource use data from the trial were valued using Canadian costs. A cost regression model was developed to estimate the mean cost of managing the clinical events over the 180 day period. Annual costs of long-term care for ACS patients were added after 180 days until death. Long-term survival was incorporated using Canadian life tables with further adjustment for additional risks associated with NSTE-ACS. Quality-of-life (utility) decrements from published sources were applied to clinical events. Lifetime costs (2009 CAD$) and quality-adjusted life-years (QALYs), discounted annually at 5 %, were estimated for the typical patient in OASIS-5 (i.e., at mean covariate values).

Results

The trial data showed that fondaparinux is protective against all clinical events observed in the trial. The model showed that: over 180 days, fondaparinux dominates enoxaparin, producing similar estimates of QALYs gained and saving $439; over a patient’s lifetime, fondaparinux yields an ICER of $4293/QALY. Based on PSA, the probabilities that fondaparinux dominates enoxaparin (less costly and more effective) and that is cost-effective at a $50,000 threshold were 42 % and 96 %, respectively.

Conclusions

In the Canadian hospital setting, fondaparinux is cost-effective when compared to enoxaparin for the treatment of NSTE-ACS. This result holds both in the immediate post-event period and over the lifetimes of patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-015-0175-1) contains supplementary material, which is available to authorized users.

Abstract P6-07-02: Pharmacoeconomic evaluation of denosumab for the treatment of bone metastases in patients with advanced breast cancer in Canada

Background: Skeletal-related events (SREs) occur in 80% of patients with advanced breast cancer (BC) and bone metastases. SREs are costly and can be painful and debilitating, impacting patients’ quality of life and morbidity. While intravenous bisphosphonates such as pamidronate (PAM) and zoledronic acid (ZA) have demonstrated clinical benefit in reducing SREs, skeletal metastases remain a problem as treatments that are more efficacious, well tolerated, more convenient and less costly to administer are needed. Denosumab (XGEVA™) is a novel subcutaneous human monoclonal antibody therapy that significantly reduces the risk of developing SREs in patients with bone metastases from BC.

Objective: The objective of this project is to estimate the incremental cost-effectiveness of denosumab relative to ZA and PAM in the treatment of advanced BC patients with bone metastases.

Methods: A lifetime Markov model with four-week cycle lengths was developed with three health states: on treatment; off treatment; and death. The model included the risk of an SRE for patients on and off treatment and adverse events during treatment. Efficacy was measured as reduction in SREs. Head-to-head efficacy data, transition probabilities, and risk of adverse events were obtained from the clinical trial of denosumab versus ZA. (Stopeck AT et al JCO 2010) Efficacy data compared to PAM was determined from a published network meta-analysis. (Ford JA et al Eur J Cancer 2012) The baseline SRE risk was derived from clinical trial data due to the absence of real-world Canadian data. Analyses were conducted from the Canadian healthcare system perspective and reported in 2011 $CAD. Resource use was determined from a Canadian retrospective chart review of oncology patients with SREs. Costs were based on the published literature, the Ontario Case Costing Initiative, and input from a physician panel. Utility inputs were based on a time trade-off study. (Matza LS et al. Eur J Health Econ 2013) Bisphosphonate administration costs were derived from a published time and motion study. (Dranitsaris G et al. J Oncol Pharm Pract 2001) Outcomes were measured as both SREs avoided and quality-adjusted life years (QALYs) gained. Dominance was assessed or incremental cost-effectiveness ratios calculated per SRE avoided and per QALY gained, for denosumab compared to ZA and PAM. Future costs and QALYs were discounted at 5% per annum. Sensitivity analyses were conducted to test the robustness of the results.

Results: Denosumab was dominant and resulted in $5,733 in cost savings compared to ZA and $2,566 in cost savings compared to PAM based on a probabilistic analysis. Cost savings was driven by differences in drug administration costs and reduction in SREs. SREs avoided were 0.27 and 0.57 compared to ZA and PAM respectively. Denosumab resulted in 0.012 QALYs gained and 0.025 QALYs gained per patient compared to ZA and PAM, respectively. Sensitivity analyses showed the results were robust but most sensitive to drug administration costs and the relative risk of SREs.

Conclusion: Compared to both ZA and PAM, denosumab is more efficacious and offers better value for money (i.e. dominant) in Canada for managing SREs in patients with advanced BC and bone metastases.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-07-02.

Anti-tumor activity of motesanib in a medullary thyroid cancer model

BACKGROUND

Medullary thyroid cancer (MTC) is frequently associated with mutations in the tyrosine kinase Ret and with increased expression of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). Motesanib is an investigational, orally administered small molecule antagonist of VEGFR1, 2, and 3; platelet-derived growth factor receptor (PDGFR); Kit; and possibly Ret.

AIM

The aim of this study was to investigate the effects of motesanib on wildtype and mutant Ret activity in vitro and on tumor xenograft growth in a mouse model of MTC.

METHODS/RESULTS

In cellular phosphorylation assays, motesanib inhibited the activity of wild-type Ret (IC(50)=66 nM), while it had limited activity against mutant Ret C634W (IC(50)=1100 nM) or Ret M918T (IC(50)>2500 nM). In vivo, motesanib significantly inhibited the growth of TT tumor cell xenografts (expressing Ret C634W) and significantly reduced tumor blood vessel area and tumor cell proliferation, compared with control. Treatment with motesanib resulted in substantial inhibition of Ret tyrosine phosphorylation in TT xenografts and, at comparable doses, in equivalent inhibition of VEGFR2 phosphorylation in both TT xenografts and in mouse lung tissue.

CONCLUSIONS

The results of this study demonstrate that motesanib inhibited thyroid tumor xenograft growth predominantly through inhibition of angiogenesis and possibly via a direct inhibition of VEGFR2 and Ret expressed on tumor cells. These data suggest that targeting angiogenesis pathways and specifically the VEGF pathway may represent a novel therapeutic approach in the treatment of MTC.

A health impact assessment of the 2014 Commonwealth Games in Glasgow

OBJECTIVE

To influence the planning of the 2014 Commonwealth Games such that the positive impacts are maximized and the negative impacts are mitigated.

STUDY DESIGN

Participatory health impact assessment (HIA).

METHODS

A participatory HIA was performed using standard World Health Organization methods. A scoping event was held to involve decision makers in the process and to identify the key areas for consideration. A large community engagement exercise and a systematic review were conducted as part of the evidence-gathering phase. The results of the HIA were reported to the key decision makers involved in the Glasgow City Council legacy strategy.

RESULTS

The likely net health impact of hosting the Commonwealth Games was uncertain. It was suggested that the main mechanisms through which impacts were likely to be felt were: the economy; civic pride; engagement in decision making; the provision of new infrastructure; and participation in cultural events. A series of recommendations was produced in order to maximize positive health benefits and mitigate negative impacts.

CONCLUSIONS

HIA is a useful tool for engaging communities and decision makers in the public health agenda. HIAs of major multi-sport events are limited by a lack of quality evidence and the inability to predict impacts reliably.

Case of the month: Buffalo chest: a case of bilateral pneumothoraces due to pleuropleural communication

Simultaneous spontaneous bilateral pneumothoraces, the presentation of separate right and left pneumothoraces together, is a rare event. The pleural cavities in humans are separated completely and the only previous reports of pleuropleural communication have been associated with major invasive thoracic procedures, specifically mediastinal surgery. The term "buffalo chest" has been coined for the condition on the basis that the buffalo or bison has a single pleural cavity, one of the few mammals to do so. We present the case of a woman with a past history of a single right sided spontaneous pneumothorax but no major thoracic surgery, who presented to the emergency department with a second spontaneous right pneumothorax that was under tension. After thoracostomy, she was found to have bilateral pneumothoraces which resolved with a unilateral chest drain demonstrating pleuropleural communication. We believe this to be the first reported case of such a presentation in the literature. The case demonstrates an unusual emergency presentation of a rare anatomical anomaly.

Comprehensive DNA methylation profiling in a human cancer genome identifies novel epigenetic targets

Using a unique microarray platform for cytosine methylation profiling, the DNA methylation landscape of the human genome was monitored at more than 21,000 sites, including 79% of the annotated transcriptional start sites (TSS). Analysis of an oligodendroglioma derived cell line LN-18 revealed more than 4000 methylated TSS. The gene-centric analysis indicated a complex pattern of DNA methylation exists along each autosome, with a trend of increasing density approaching the telomeres. Remarkably, 2% of CpG islands (CGI) were densely methylated, and 17% had significant levels of 5 mC, whether or not they corresponded to a TSS. Substantial independent verification, obtained from 95 loci, suggested that this approach is capable of large scale detection of cytosine methylation with an accuracy approaching 90%. In addition, we detected large genomic domains that are also susceptible to DNA methylation reinforced inactivation, such as the HOX cluster on chromosome 7 (CH7). Extrapolation from the data suggests that more than 2000 genomic loci may be susceptible to methylation and associated inactivation, and most have yet to be identified. Finally, we report six new targets of epigenetic inactivation (IRX3, WNT10A, WNT6, RARalpha, BMP7 and ZGPAT). These targets displayed cell line and tumor specific differential methylation when compared with normal brain samples, suggesting they may have utility as biomarkers. Uniquely, hypermethylation of the CGI within an IRX3 exon was correlated with over-expression of IRX3 in tumor tissues and cell lines relative to normal brain samples.

Perchlorate in fish from a contaminated site in east-central Texas

Perchlorate, a known thyroid endocrine disruptor, contaminates surface waters near military instillations where solid fuel rocket motors are manufactured or assembled. To assess potential perchlorate exposure to fish and the human population which may feed on them, fish were collected around the Naval Weapons Industrial Reserve Plant in McLennan County, TX, and analyzed for the presence of the perchlorate anion. The sampling sites included Lake Waco and Belton Lake, and several streams and rivers within their watersheds. The general tendency was that perchlorate was only found in a few species sampled, and perchlorate was not detected in every individual within these species. When detected in the fish, perchlorate tissue concentrations were greater than that in the water. This may be due to highly variable perchlorate concentrations in the water coupled with individual-level variation in elimination from the body, or to routes of exposure other than water.

Effects of atrazine on metamorphosis, growth, and gonadal development in the green frog (Rana clamitans)

Embryos of the green frog (Rana clamitans) were collected from the field and exposed to 1 of 6 water-borne treatments for 273 d (mid July 2001 to mid April 2002). The treatments were 0, 10, or 25 microg/L atrazine, 0.005% ethanol (EtOH), or 0.1 mg/L estradiol or dihydrotestosterone carried in 0.005% EtOH. Treatments were applied in a static renewal system with a 50% test solution replacement approximately every 3 d. Following the exposure period, tadpoles were reared in freshwater until metamorphosis or until study termination (at d 506). Time to initiate and complete metamorphosis, stage-specific mortality, length and weight at metamorphosis, and gross morphology and histology of the gonads were examined. At environmentally relevant concentrations, atrazine did not consistently affect growth or metamorphosis. Compared to controls, the length of the larval period was greater in tadpoles exposed to 10 microg/L atrazine. However, the length of the larval period was not markedly different between tadpoles in the control and 25 microg/L atrazine treatments. Neither gross gonadal morphology nor histopathology of the gonads in postmetamorphic frogs was significantly altered in response to atrazine exposure. This study provides evidence that environmentally relevant concentrations of atrazine do not adversely affect the growth or reproductive development of R. clamitans.

Emergency nurse practitioners: a three part study in clinical and cost effectiveness

AIMS

To compare the clinical effectiveness and costs of minor injury services provided by nurse practitioners with minor injury care provided by an accident and emergency (A&E) department.

METHODS

A three part prospective study in a city where an A&E department was closing and being replaced by a nurse led minor injury unit (MIU). The first part of the study took a sample of patients attending the A&E department. The second part of the study was a sample of patients from a nurse led MIU that had replaced the A&E department. In each of these samples the clinical effectiveness was judged by comparing the "gold standard" of a research assessment with the clinical assessment. Primary outcome measures were the number of errors in clinical assessment, treatment, and disposal. The third part of the study used routine data whose collection had been prospectively configured to assess the costs and cost consequences of both models of care.

RESULTS

The minor injury unit produced a safe service where the total package of care was equal to or in some cases better than the A&E care. Significant process errors were made in 191 of 1447 (13.2%) patients treated by medical staff in the A&E department and 126 of 1313 (9.6%) of patients treated by nurse practitioners in the MIU. Very significant errors were rare (one error). Waiting times were much better at the MIU (mean MIU 19 minutes, A&E department 56.4 minutes). The revenue costs were greater in the MIU (MIU pound 41.1, A&E department pound 40.01) and there was a great difference in the rates of follow up and with the nurses referring 47% of patients for follow up and the A&E department referring only 27%. Thus the costs and cost consequences were greater for MIU care compared with A&E care (MIU pound 12.7 per minor injury case, A&E department pound 9.66 per minor injury case).

CONCLUSION

A nurse practitioner minor injury service can provide a safe and effective service for the treatment of minor injury. However, the costs of such a service are greater and there seems to be an increased use of outpatient services.

Red cell folate in elderly patients with myelodysplastic syndrome

During a 7-month period a prospective study of 71 anaemic patients (29 males and 42 females) over the age of 50 was undertaken in order to identify patients with myelodysplastic syndrome (MDS). The mean values of mean corpuscular volume (MCV), serum ferritin, folate, vitamin B12 and red cell folate (RCF) of patients grouped according to the diagnosis were compared to those observed in age-matched blood donors. Forty-four of the 71 elderly patients showed macrocytic anaemia: 21 of them had gastric disease and the remaining 23 MDS. Two further patients with MDS showed microcytic anaemia. The 25 patients diagnosed with MDS were subclassified according to the FAB nomenclature: 9 had a refractory anaemia with excess of blasts and 16 refractory anaemia. The mean values of MCV, serum folate, ferritin, vitamin B12 and RCF were statistically different between patients with macrocytic anaemia due to gastric disease and patients with MDS. Among patients with MDS, the RCF level pathologically high was inversely correlated to the haemoglobin level (r=-0.39; p<0.05). Thus the RCF and serum folate may represent useful parameters for the diagnosis of MDS in elderly anaemic patients.

Simultaneous differentiation and quantitation of erythroblasts and white blood cells on a high throughput clinical haematology analyser

After the neonatal period, the presence of nucleated red blood cells (NRBC) in peripheral blood is indicative of pathology. Despite the clinical utility of such measurements, automated NRBC counting has hitherto not been available on routine automated blood cell counting analysers. To address this, an automated method for the analysis of NRBC was developed and incorporated into the Abbott Cell Dyn 4000 (CD4000) haematology analyser. The system white blood cell (WBC) reagent was specifically formulated to preserve concomitantly white blood cell (WBC) morphology, rapidly lyse red blood cell and NRBC membranes, and subsequently stain NRBC nuclei with a nucleotide specific fluorochrome dye (Kim et al. 1996a). The fluorochrome itself does not permeabilize the membrane of intact viable white blood cells. The sample is processed by flow cytometry and the signals generated from an argon-ion laser light source are analysed. Axial light loss (AxLL), intermediate angle light scatter (IAS) and red fluorescence (FL3) are used to discriminate between particles of various types. By using these discriminators in a three-dimensional approach, NRBC from a discrete cluster which can easily be separated from leucocytes and enumerated as a distinct cell population during the optical WBC differential analysis. Consequently, accurate absolute WBC counts and differentials can be obtained even in the presence of NRBC. Background 'noise' (both fluorescent and non-fluorescent) from platelets. Howell-Jolly bodies, basophilic stippling, RNA from lysed reticulocytes, and DNA from leucocyte and megakaryocytic fragments are essentially eliminated (Kim et al. 1996b). While the membranes of intact and viable leucocytes remain impermeable to the passage of the fluorochrome stain, leucocytes with damaged membranes are permeable to the dye and generate FL3+ signals. Such cells, which are commonly seen as a consequence of sample ageing as well as in some distinctive pathologies, are identified by the algorithm (using their AxLL signal size) and are labelled as non-viable. Moreover, because non-viable leucocytes are retained in the WBC count and differential analyses, the CD4000 is further able to provide both numerical and graphical data regarding the relative frequency of viable and non-viable components. This additional information can serve as valuable 'decision-drivers' in the laboratory data review process.

Evaluation of the Abbott Cell Dyn 4000 automated fluorescent reticulocyte measurements: comparison with manual, FACScan and Sysmex R1000 methods

The Abbott Cell Dyn 4000 (CD4000) is the first haematology analyser in which fully-automated reticulocyte measurements can be routinely determined by fluorescence as part of the full blood count. This communication reports the first evaluation of this method which was undertaken by three independent reference laboratories in Belgium, Germany and Italy. A total of 695 different samples was entered into the study which was designed to compare CD4000 reticulocyte information (enumeration and qualitative maturational data) with results determined in parallel with the existing manual (supravital staining) reference procedure, and two semi-automated fluorescent assays (Becton Dickinson FACScan and Sysmex R1000 instruments). These studies revealed good agreement between the CD4000 and the manual procedure, with no inter-method bias. Comparison of CD4000 and FACScan reticulocyte measurements, however, indicated a distinct tendency for the FACScan to give higher reticulocyte estimates than the CD4000. Finally, the comparison of the CD4000 with the Sysmex R1000 showed excellent agreement in the range 0-6% reticulocytes, although there was some inter-method bias in the higher range (> 15%). Analysis of agreement levels between the methods using specific 'clinical decision points' confirmed the tendency for overestimation by the FACScan, in that 58% of the samples with a reticulocytopenia of < 0.5% as defined by the CD4000 gave FACScan results within the normal range (0.5-1.8%). In contrast, there was absolute agreement between the CD4000 and the Sysmex R1000 for all reticulocytopenias. Comparison (195 samples) of instrument fluorescent reticulocyte maturation profiles demonstrated an exponential relationship (r = 0.78) between CD4000 IRF and R1000 HFR (highly fluorescent reticulocyte fraction) values. The suggestion that the CD4000 IRF values includes some of the MFR as well the HFR reticulocyte fraction was confirmed as the correlation between the CD4000 IRF and the Sysmex R1000 MFR plus HFR percentages was linear (r = 0.82). This study confirms a high performance level for the CD4000 automated fluorescent reticulocyte method.

Central pontine myelinolysis after an operation

Images

Risk of neural tube defect-affected pregnancy is associated with a block in maternal one-carbon metabolism at the level of N-5-methyltetrahydrofolate:homocysteine methyltransferase

The disposition of whole blood mono-to hexaglutamyl methylfolate and plasma homocysteine (HCY) was used to evaluate potential lesion sites in one-carbon metabolism which could be responsible for neural tube defect(NTD)-affected pregnancies. An isocratic high-performance liquid chromatographic system (HPLC) with photodiode array detection was used to quantify and speciate whole-blood methylfolate into mono-, di-, tri-, tetra-, penta-, and hexaglutamate forms. This technique was also used with off-line radioassay to identify nonmethyl whole-blood folates. Isocratic HPLC with fluorescence detection was used to quantify SBDF derivatized homocysteine in plasma. The study investigated blood from 11 women who had experienced a previous NTD-affected pregnancy and 11 controls of similar age and social class. No subjects were pregnant. HCY levels were significantly higher in NTD subjects (P = 0.0486, 95% CI-2.799,0.001 using the Mann-Whitney test), as was the ratio of known intracellular (tri-to hexaglutamyl) methylfolate compared to extracellular (mono- and diglutamyl) methylfolate (P = 0.0062 95% CI-0.543, 3.862 using the Mann-Whitney test). Vitamin B12, red cell folate, circulating total methylfolate, and circulating mono-to hexaglutamyl methylfolates showed no difference between population groups. The disposition between individual and cumulative glutamate chain lengths of methylfolate showed significant trends which differed between population groups: (i) total blood methylfolate (Glu1-6) appears to be utilized by N-5-methyltetrahydrofolate:homocysteine methyltransferase (MS) in control blood but not NTD blood, where it appears to accumulate following a 45-min incubation; (ii) whole-blood hexaglutamyl methylfolate (5CH3-H4PteGlus) becomes a larger proportion of the total blood methylfolate in NTD than in control populations; and (iii) the intermediate glutamate chains of methylfolate (Glu1-5) remain relatively constant as 5CH3-H4PteGlu6 accumulates in NTD but appear to increase linearly with 5CH3-H4PteGlu6 in controls. The significant elevation of HCY in the NTD population is associated with the increasing proportion of 5CH3-H4PteGlu6 relative to the total methylfolate, since, when corrected for HCY level, the proportion of 5CH3-H4PteGlus to total methylfolate is similar in NTD and control populations. These trends are consistent with a defect at the level of vitamin B12 dependent MS which "traps" folate at the 5CH3-H4PteGlus level.

Serum erythropoietin during autologous bone marrow transplantation: relationship to measures of erythroid activity

Marked elevation of serum erythropoietin (sEPO) occurs following high dose chemotherapy for malignant disease. It has been proposed that the subsequent fall in sEPO constitutes a relative erythropoietin (EPO) deficiency, prompting trials of recombinant EPO to reduce red cell transfusion during chemotherapy. We have investigated these phenomena by serial estimations of reticulocytes and sEPO in 11 autologous marrow transplant recipients. sEPO reached two to five times baseline 0 to 5 days after transplant but the inverse relationship between sEPO and haematocrit was maintained. Observed to expected log sEPO (Epo ratio) rose and fell in parallel with sEPO, remaining greater than 1.0 throughout. A progressive fall in reticulocyte count during chemotherapy was followed by an increase during engraftment. The strong inverse relationships between reticulocytes and Epo ratio in the 10 days after initiating chemotherapy support the hypothesis that loss of EPO-receptor bearing erythroid precursors allows a rise in sEPO during chemotherapy. The elevation of Epo ratio levels during engraftment indicates that it is the availability of EPO-sensitive progenitors, rather than the supply of EPO, that limits the rate of resumption of erythropoiesis after high-dose chemotherapy.

Estimation of effective and total erythropoiesis in myelodysplasia using serum transferrin receptor and erythropoietin concentrations, with automated reticulocyte parameters

The erythroid abnormality in patients with myelodysplasia (MDS) is multifactorial, with ineffective erythropoiesis and poor in vitro progenitor response to erythropoietin (EPO). Serum EPO concentration is variable among patients for a given haemoglobin concentration. We studied 19 non-transfusion-dependent patients with MDS, and 13 healthy elderly control subjects in an attempt to define the factors governing variability in serum EPO and to further characterise the anaemia of MDS. Serum EPO concentration was appropriate for the degree of anaemia in 15/19 MDS patients, and was positively related to mean cell volume (MCV), mean cell haemoglobin (MCH), and percentage highly fluorescent reticulocytes (% HFR), but not to absolute or percentage reticulocyte count. Although the observed/predicted ratio for serum transferrin receptor (TfR) concentration was low in 12 of 19 MDS subjects, no relationship to haemoglobin concentration, reticulocytes or serum EPO was seen. Serum TfR was positively correlated with WBC and platelet counts. Serum TfR was higher in patients with sideroblastic anaemia than refractory anaemia. Standardized in vivo p50 was positively correlated to red cell 2,3 diphosphoglycerate concentration, although this was not the only factor influencing the oxygen dissociation curve. We conclude that effective erythroid output responsive to endogenous EPO drive in MDS is positively related to MCV, MCH and % HFR. Serum TfR may not represent effective output as precisely as % HFR, but may be proportional to total marrow erythropoietic activity.

The relationship of haemoglobin to serum erythropoietin concentrations in the anaemia of rheumatoid arthritis: the effect of oral prednisolone

Previous studies of the erythropoietin response to anaemia in RA have yielded conflicting findings. Some have found the response to be impaired and others have found a normal response. We have compared erythropoietin (EPO) levels measured by radioimmunoassay, in 54 anaemic rheumatoid patients and 55 patients with iron deficiency anaemia but no inflammatory disease. The erythropoietin response in the rheumatoid patients was impaired compared with the control group (P < 0.025) but only seven rheumatoid patients showed a response which fell below the 95% confidence intervals predicted for the control group. Rheumatoid patients who fell within the highest quartile for serum ferritin concentrations (i.e. those most likely to have anaemia of chronic disease) had significantly lower EPO levels compared with the control group (P < 0.01). EPO levels in rheumatoid patients within the lowest quartile for ferritin (i.e. those with iron deficiency anaemia) were not significantly different from the control group (P = 0.670). The difference in EPO response between the RA patients in the upper and lower quartile for ferritin approached but did not achieve significance (P = 0.056). In a second study 15 anaemic RA patients were given a 5-day course of oral prednisolone 1.5 mgkg-1. Hemoglobin did not rise significantly until day 4 but EPO levels fell by day 1 (P < 0.005) and remained lower than pretreatment values throughout the study. Thus, in RA patients, anaemia of chronic disease is associated with inappropriately low EPO concentrations but this does not appear to be the major cause of the anaemia and Hb response to prednisolone does not depend upon an increase in EPO concentration.

Captopril and hydrochlorthiazide--a safe antihypertensive for use in general practice?

The combination of captopril and hydrochlorthiazide was assessed in 15 hypertensive patients in a general practice setting. The first aim was to determine whether the fall in blood pressure, noted after the first dose of an ACE inhibitor given alone, became unacceptable when the drug was given with a diuretic. The second aim was to assess the impact of the ACE inhibitor on the biochemical abnormalities associated with thiazide diuretic therapy. The drug combination markedly reduced blood pressure but not below 110 systolic after the first dose. In the long-term the treatment significantly lowered blood pressure but did not produce any significant or clinically relevant changes in serum chemistry.

A generalized allergic reaction with acute interstitial nephritis following trimethoprim-sulfamethoxazole use

A severe generalized multisystem allergic reaction occurred in a 16-month-old infant following the use of trimethoprim-sulfamethoxazole. Acute interstitial nephritis developed three weeks following the onset of this reaction and resolved after three months. This is the first description of this renal toxicity with TMP-SMX in a child.

Immunomodulating properties of dimethylglycine in humans

Dimethylglycine (DMG), a tertiary amino acid, has had wide acceptance as a nonfuel nutrient; presumably it enhances oxygen utilization by tissue and complexes free radicals. Its potential as an immunoadjuvant has also been suggested by a study of an analog of DMG, calcium pangamate. A double-blind study in 20 human volunteers showed a fourfold increase in antibody response to pneumococcal vaccine in those receiving DMG orally as compared with controls (P less than 0.01). Production of leukocyte inhibitory factor in response to concanavalin A was similar in the two groups, but those taking DMG tablets had a significantly highr mean response of leukocyte inhibition factor to streptokinase-streptodornase (P less than 0.001). The in vitro responses of lymphocytes from patients with diabetes and those with sickle cell disease to phytohemagglutinin, convanavalin A, and pokeweed mitogen were increased almost threefold after addition of DMA. These results suggest that DMG enhances both humoral and cell-mediated immune responses in humans.