High-sensitivity troponin is a biomarker of medium term mortality in 20,000 consecutive hospital patients undergoing a blood test for any reason

Introduction

High sensitivity troponin (hs-cTn) concentrations above the manufacturer recommended upper limit of normal (ULN) are frequently seen in patients without a clinical presentation consistent with type 1 myocardial infarction. There is increasing evidence that these concentrations may act as a marker of prognosis in a range of conditions. However, previous studies have been limited because they have only included patients in whom the clinician has requested the test. The aim of this study was to assess the relationship between medium term mortality and hs-cTn concentration in a large consecutive hospital population undergoing a blood test, regardless of whether there was a clinical indication for performing the hs-cTn.

Method

This single centre study included 20,000 consecutive patients undergoing a blood test for any reason, in whom hs-cTnI was added, regardless of the clinical indication (CHARIOT population). Mortality data up to 2.25 years was obtained via NHS Digital. The association between hs-cTnI concentration and one year mortality was evaluated using Kaplan-Meier plots (with log-rank test) and Cox proportional hazards analyses. After the cohort was considered as a whole, each of the clinical areas (inpatient (IPD), outpatient (OPD), emergency department (ED)) were considered separately. Furthermore, in the IPD and ED populations, a landmark analysis was performed excluding those patients who died within 30 days to assess whether any longer term relationship was driven by short term mortality.

Results

Overall, 2825 (14.1%) patients had died at 2.25 years. The mortality at 2.25 years was significantly higher if the hs-cTnI concentration was above the ULN (45.3% versus 12.3%, p<0.001 (log rank) in the entire cohort (Figure 1). Multivariable Cox regression analysis demonstrated that the log10hs-cTnI concentration was independently associated with 2.25 year mortality (hazard ratio (HR) 1.69 (95% confidence interval (CI): 1.59–1.80)). This relationship was demonstrated for patients in each of the clinical areas (IPD HR 1.46 (95% CI: 1.33–1.60), OPD HR 2.19 (95% CI: 1.84–2.60), ED HR 1.87 (95% CI: 1.68–2.07)). Further analysis by excluding those patients that died within 30 days demonstrated that the relationship between hs-cTnI concentration and mortality persisted and it was not driven by short term mortality.

Conclusion

In a large, unselected hospital population of both in- and out-patients, the majority of whom there was no clinical indication for testing, hs-cTnI concentration was independently associated with medium term mortality. These data suggest that hs-cTnI may have a role as a biomarker of future risk.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Beckman Coulter

The prevalence and significance of mitral annular disjunction on clinical outcomes in patients undergoing mitral valve surgery

Funding Acknowledgements

Type of funding sources: None.

Background

Mitral annular disjunction (MAD) is a common structural abnormality involving a distinct separation of the left atrium/mitral valve annulus and myocardium continuum. MAD is commonly associated with altered mitral valve annular dynamics, increased left ventricular and mitral valve apparatus stress and potentially life threatening arrhythmias. At present there is limited data on the prevalence and significance of MAD in patients requiring mitral valve surgery.

Purpose

To ascertain the prevalence, extent and significance of MAD on a general cohort of patients with mitral valve disease who required mitral valve surgery. Primary outcomes included: duration of surgery, need for re-do operation (any cause), neurological and gastro-intestinal complications, cardiogenic shock and mortality. These were assessed during the surgical hospitalisation period.

Methods

The local cardiothoracic database within a large tertiary centre was used to identify all patients who underwent mitral valve surgery between 2013 and 2020. From this, patients who were found to have a transthoracic echocardiogram (TTE) pre and post mitral valve surgery were included. Two experienced sonographers retrospectively reviewed and analysed each TTE. The data collected included: presence, location and extent of MAD (pre and post-surgery). The local cardiothoracic database and electronic patient records were reviewed for primary outcomes.

Results

A total of 187 patients were included (age: 65.6 ± 13.7 years, 74.2% males). The most common reason for mitral valve surgery was mitral valve prolapse (31.6%), remaining aetiologies included functional MR, ischemic MR, infective endocarditis, rheumatic mitral stenosis and congenital abnormalities. Surgical intervention included: leaflet repair ± annuloplasty ring (57.2%), bio-prosthesis (19.8%) or mechanical prosthesis (23.0%). Pre surgery, MAD was present in 32.6% of all patients and was most commonly seen in patients with mitral valve prolapse (21.3%). In patients with MAD, the averaged MAD length was 8.4 ± 3.9mm (median 7 [IQR: 5-11]). Post-surgery, MAD was only identified in 2 patients, both of whom had mitral valve repair± annuloplasty ring. As seen in Table 1, there were no significant differences in clinical outcomes in patients with or without MAD.

Conclusion

MAD is common in a cohort of patients requiring mitral valve surgery. Surgical intervention is able to correct MAD in the vast majority of patients and its presence does not affect immediate post-surgical outcomes. Abstract Table 1.

Incidence and one year outcome of periprocedural myocardial infarction following cardiac surgery: are the universal definition and SCAI criteria fit for purpose?

Introduction

The diagnosis and clinical implication of periprocedural myocardial infarction (PPMI) following coronary artery bypass grafting (CABG) is contentious, especially given its importance in the interpretation of trial data. Two accepted definitions of PPMI yield discrepant results. Little is known about the association between the diagnosis of PPMI, using high sensitivity troponin (hs-cTn), and medium term mortality in patients who undergo CABG, either alone or in conjunction with another procedure. In addition, there are currently no criteria for the diagnosis of PPMI following non-CABG surgery.

Method

Consecutive patients admitted to a cardiothoracic critical care unit (CCCU) over a six month period following open cardiac surgery had hs-cTnI assay performed on admission and every day for forty-eight hours, regardless of whether there was a clinical indication. Patients were categorised as PPMI using both the Universal Definition of MI (UDMI) and Society of Cardiovascular Angiography and Interventions (SCAI) criteria. Comorbidity data, surgical details and clinical progress in CCCU were recorded. One year mortality data were obtained from NHS Digital.

Results

There were 245 CABG patients, of whom 20.4% met criteria for UDMI PPMI and 87.6% for SCAI UDMI (figure 1). The diagnosis of UDMI PPMI was independently associated with one year mortality (hazard ratio 4.175 (95% confidence interval 1.281 – 13.608)), whereas there was no association between SCAI PPMI and one year mortality (figure 2). Of the 243 patients who had non CABG cardiac surgery, 11.4% met criteria for UDMI PPMI and 85.2% for SCAI PPMI (figure1) but neither was associated with one year mortality.

Conclusions

The incidence of SCAI PPMI in a real world cohort of cardiac surgery patients is so high as to be of limited clinical value. By contrast, a diagnosis of UDMI PPMI post CABG is independently associated with one year mortality, so may have clinical utility.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Beckman Coulter - supplied the assays used in the study but had no role in the study Figure 1. Frequency of PPMIFigure 2. Kaplan Meier curves

The relationship between high-sensitivity troponin taken on admission to critical care, regardless of whether there was a clinical indication for testing, and one year mortality

Introduction

High-sensitivity troponin (hs-cTn) assays now form a key component of the diagnostic pathways for patients presenting to emergency medical services with chest pain. However, hs-cTn concentrations above the manufacturer-provided upper limit of normal (ULN) are now frequently reported in patients presenting with conditions not traditionally associated with type 1 myocardial infarction (T1MI). This is particularly true of severe illness states. We investigated the possible association between hs-cTn and 1 year mortality in critical care patients.

Method

Consecutive patients admitted to two adult critical care units (general critical care unit (GCCU) and neuroscience critical care unit (NCCU)) over a six month period had hs-cTnI assay performed on admission, regardless of whether there was a clinical indication, and the results nested unless a clinical request had been made. Comorbidity data, illness severity and critical care outcome were recorded and have been previously reported. One year mortality data were obtained from NHS Digital.

Results

After excluding patients diagnosed with T1MI by the clinical team, there were 1,033 patients remaining. At one year a total of 253 (24.5%) patients had died. The Kaplan-Meier curves in figure 1 demonstrate a positive association between mortality and increasing hs-cTnI concentrations relative to the ULN. Specifically, using the log-rank test, the mortality at one year was significantly higher (p<0.001) in patients with hs-cTnI concentrations above the ULN. Furthermore, on multivariable Cox regression analysis, the log(10) hs-cTnI concentration was independently associated with the hazard of one year mortality (hazard ratio 1.587 (95% confidence interval 1.358–1.856).

Conclusions

These data suggest that admission hs-cTnI is a biomarker for one year mortality in critical care patients. Further work is now required to assess whether any medical intervention can alter this risk.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Beckman Coulter provided the assays for the tests used in this study. They had no other involvement in the study

1673 Accuracy and prognostic value of physiologist-led stress echocardiography for coronary disease

Funding Acknowledgements

No funding sources

Background

Cardiac physiologist-led stress echocardiography (PLSE) services provide potential for expansion of SE services and increased productivity for cardiologists. There is no published data on the accuracy or prognostic value of PLSE.

Purpose

To assess and compare the accuracy and prognostic value of PLSE and cardiologist-led stress echocardiography (CLSE) for CAD assessment

Methods

Retrospective study of 898 subjects undergoing PLSE (n = 393) or CLSE (n = 505) for CAD assessment using exercise or dobutamine. For accuracy assessment, the primary outcome was the ability of stress echocardiography to identify significant CAD on invasive angiography (ICA). Incidence of 24-month non-fatal myocardial infarction (MI), total and cardiac mortality, revascularisation and combined major adverse cardiac events (MACE) were assessed.

Results

Demographics, comorbidities, CAD predictors and cardiac medications were matched between the PLSE and CLSE groups. PLSE had high sensitivity, specificity, positive and negative predictive value and accuracy (85%, 74%, 69%, 88%, 78% respectively). PLSE accuracy measures were similar and non-inferior to CLSE. There was a similar incidence of individual and combined outcomes in PLSE and CLSE subjects. Negative stress echocardiography conferred a low incidence of non-fatal MI (PLSE 1.4% vs. CLSE 0.9%, p = 0.464), cardiac mortality (0.6% vs. 0.0%, p = 0.277) and MACE (6.8% vs. 3.1%, p = 0.404).

Conclusion

This is the largest study of PLSE accuracy and first study of the prognostic value of PLSE. PLSE demonstrates high and non-inferior accuracy compared with CLSE for CAD assessment. Negative PLSE and CLSE confer a similarly very low incidence of cardiac outcomes, confirming for the first time the important prognostic value of PLSE.

Accuracy of PLSE and CLSE for CAD Marker of diagnostic test Total (n = 72) PLSE (n = 32) CLSE (n = 40) p Significant CAD present (n, %) 20 (27.8%) 12 (37.5%) 8 (20.0%) 0.167 * Single-vessel CAD 12 (60.0%) 7 (58.3%) 5 (62.5%) 0.325 * Multi-vessel CAD 8 (40.0%) 5 (41.7%) 3 (37.5%) 0.325 Sensitivity 76% (66-76%) 85% (73-97%) 63% (48-78%) Non-significant Specificity 73% (63-73%) 74% (59-89%) 72% (58-86%) Non-significant Positive predictive value (PPV) 53% (42-64%) 69% (53-85%) 29% (15-43%) Significant Negative predictive value (NPV) 88% (80-96%) 88% (77-99%) 88% (78-98%) Non-significant Overall accuracy 74% (64-84%) 78% (64-92%) 70% (56-84%) Non-significant Accuracy data expressed as value (95% confidence interval). CAD= coronary artery disease. Differences in values between PLSE and CLSE considered statistically significant if no crossover in 95% confidence intervals

Abstract 1673 Figure. Predicted coronary artery lesion from SE

P676Percutaneous coronary intervention and clinical outcomes in patients with lymphoma: a 10-year period United States nationwide inpatient sample (NIS) analysis

Background

Clinical outcomes and characteristics of patients with lymphoma undergoing percutaneous coronary intervention (PCI) are unknown.

Purpose

To describe clinical characteristics and procedural outcomes in patients that underwent PCI and had a concurrent diagnosis of Hodgkin (HL) or non-Hodgkin (NHL) lymphoma and compare risks of complications and in-hospital mortality in lymphoma subtypes to patients without lymphoma.

Methods

A total of 6,413,175 PCI procedures undertaken in the United States between 2004 and 2014 in the Nationwide Inpatient Sample were included in the analysis. Multivariable regression analysis was performed in order to examine the association between lymphoma diagnosis and clinical outcomes post-PCI including complications and in-hospital mortality.

Results

Patients with lymphoma generally had a significantly higher incidence of post-PCI complications and in-hospital mortality compared to patients without lymphoma (Figure 1). Patients with lymphoma were more likely to experience in-hospital mortality (OR 1.34, 95% CI 1.20–1.49), stroke or transient ischemic attack (TIA) (OR 1.59, 95% CI 1.47–1.73), and any in-hospital complication (OR 1.19, 95% CI 1.14–1.25), following PCI. In the lymphoma subtype-analysis, diagnosis of HL was associated with an increased likelihood of in-hospital death (OR 1.31, 95% CI 1.17–1.48), any in-hospital complication (OR 1.20, 95% CI 1.14–1,26), bleeding complications (OR 1.12 95% CI 1.05–1.19) and vascular complications (OR 1.10 95% CI 1.03–1.17) while these risks were not significantly associated with NHL diagnosis. Finally, both types of lymphoma were associated with an increased likelihood of stroke/TIA following PCI, with this effect being twice greater for HL than NHL diagnosis (OR 1.66, 95% CI 1.52–1.81 and OR 1.33, 95% CI 1.06–1.66, respectively) (Table 1).

Table 1. ORs for clinical outcomes Variable HL vs. No Lymphoma NHL vs. No Lymphoma Bleeding complications 1.12 (1.05–1.19) 1.07 (0.89–1.27) Vascular complications 1.10 (1.03–1.17) 1.13 (0.92–1.27) Cardiac complications 0.94 (0.85–1.03) 0.86 (0.68–1.11) Post-procedural stroke/TIA 1.66 (1.52–1.81) 1.33 (1.06–1.66) Any complication 1.20 (1.14–1.26) 1.04 (0.91–1.18) In-hospital mortality 1.31 (1.17–1.48) 0.89 (0.65–1.21) HL, Hodgkin's Lymphoma; NHL, non-Hodgkin's Lymphoma; TIA, Transient Ischemic Attack.

Figure 1. Type of lymphoma and outcomes

Conclusions

While the incidence of lymphoma in the observed PCI cohort was low, a diagnosis of lymphoma was associated with an adverse prognosis following PCI, primarily in patients with a diagnosis of HL.

P681Acute Myocardial Infarction in patients with Leukaemia: A national analysis of prevalence, predictors and outcomes in United States hospitalisations (2004 to 2014)

Background

Patients with leukaemia are at increased risk of cardiovascular events. There is limited outcomes data for patients with a history of leukaemia who present with an acute myocardial infarction (AMI).

Purpose

To examine the prevalence and clinical characteristics of patients with leukaemia presenting with AMI, and evaluate differences in clinical outcomes according to the subtype of leukaemia in comparison to patients without leukaemia.

Methods

We analysed the Nationwide Inpatient Sample (2004–2014) for patients with a primary discharge diagnosis of AMI and concomitant leukaemia, and further stratified according to the subtype of leukaemia into 4 groups; AML; ALL; CML; and CLL. Multiple logistic regression was conducted to identify the association between leukaemia and major acute cardiovascular and cerebrovascular events (MACCE; composite of mortality, stroke and cardiac complications) and bleeding.

Results

Out of 6,750,927 AMI admissions, a total of 21,694 patients had a leukaemia diagnosis. The leukaemia group experienced higher rates of MACCE (11.8% vs. 7.8%), mortality (10.3% vs. 5.8%) and bleeding (5.6% vs. 5.3%). Following adjustments, leukaemia was independently associated with increased odds of MACCE (OR 1.26 [1.20,1.31]) and mortality (OR 1.43 [1.37,1.50]) without an increased risk of bleeding (OR 0.86 [0.81,0.92]). Acute myeloid leukaemia (AML) was associated with approximately three-fold risk of MACCE (RR 2.81 [2.51, 3.13]) and a four-fold risk of mortality (RR 3.75 [3.34, 4.22]) (Figure 1). Patients with leukaemia were less likely to undergo coronary angiography (CA) (48.5% vs. 64.5%) and percutaneous coronary intervention (PCI) (28.2% vs. 42.9%) compared to those without leukaemia.

Figure 1.Relative risk of adverse events

Conclusion

Patients with leukaemia, especially those with AML, are associated with poor clinical outcomes after AMI, and are less likely to receive CA and PCI compared to those without leukaemia. A multi-disciplinary approach between cardiologists and haematology oncologists may improve the outcomes of patients with leukaemia after AMI.

P3611The effect of concomitant AF on in-hospital clinical outcomes of NSTE-ACS related hospitalizations in the United States: an analysis of rates, trends and predictors from 2004 to 2014

Background

Atrial fibrillation (AF) is the most common arrhythmia in patients presenting with acute coronary syndrome (ACS).

Purpose

We sought to examine the rates, trends, and clinical outcomes of non-ST Elevation acute coronary syndrome (NSTE-ACS) related hospitalisations in the United States in patients with AF compared to those with sinus rhythm (SR).

Methods

We analysed the Nationwide Inpatient Sample (NIS) database from 2004 to 2014 for patients with a primary discharge diagnosis of NSTEMI or UA, and further stratified the cohort on the basis of diagnoses into SR and AF groups. Multivariate analysis was performed to identify the association between AF and MACCE (composite of mortality, stroke and cardiac complications), mortality, stroke, and bleeding.

Results

A total of 4,668,737 NSTE-ACS admissions were included in our analysis. The proportions of SR and AF groups were 82.4% (3,848,202) and 17.6% (820,535), respectively. The incidence of AF increased significantly over time from 16.5% in 2004 to 19.3% in 2014 (p<0.001). The AF group was at a greater risk of adverse outcomes with higher overall rates and adjusted relative risk of MACCE (12.9% vs. 5.3%; RR: 1.74 [1.72, 1.75]), mortality (6.5% vs. 3.3%. RR: 1.12 [1.11, 1.13]), stroke (2.7% vs. 1.5%; RR: 1.32 [1.30, 1.34]) and bleeding (14.7% vs. 8.8%; RR: 1.42 [1.41, 1.43]). The AF group was less likely to receive coronary angiography (47.1% vs. 58%) and PCI (18.7% vs. 32.6%) and more likely to undergo CABG (13.9% vs. 7.6%) in comparison to SR.

Figure 1. Crude rates of adverse events

Conclusion

The prevalence of concomitant Atrial Fibrillation amongst patients presenting with NSTE-ACS has increased over a decade. However, this high-risk group remains less likely to receive invasive coronary management for NSTE-ACS than patients with sinus rhythm, independent of their comorbidities, and are associated with worse clinical outcomes.

P6510Frailty and in-hospital outcomes in percutaneous coronary interventions

Background

Frailty may be an important marker for poor outcomes in percutaneous coronary intervention (PCI) and there is limited literature on outcomes based on frailty from national cohorts.

Purpose

This study evaluates the prevalence of frailty, changes in frailty over time and outcomes associated with frailty in a national American cohort of patients who underwent PCI.

Methods

The study included adults who underwent PCI in the National Inpatients Sample between 2004 and 2014. Frailty risk was determined using a validated Hospital Frailty Risk Score (HFRS) using the cutoffs <5, 5–15 and >15 corresponding to low, intermediate and high HFRS.

Results

There were 7,306,007 PCI admissions in this cohort. A total of 94.58%, 5.39% and 0.03% of admissions were for low HFRS, intermediate HFRS and high HFRS, respectively. The proportion of intermediate or high frailty risk patients increased over time from 1.9% in 2004 to 11.7% in 2014. In-hospital death increased from 1.0% with low HFRS to 13.9% with high HFRS and average length of stay increased from 2.9±3.3 days to 17.1±15.5 days from low to high HFRS. Greater frailty risk was associated with greater average inpatient cost which was $17,743±11,059, $38,824±34,809 and $56,119±49,772 for low, intermediate and high HFRS, respectively. There were increased adverse outcomes with high frailty including greater in-hospital death (OR 9.91 95% CI 7.17–13.71), in-hospital bleeding complications (OR 4.99 95% CI 3.82–6.51), in-hospital vascular complications (OR 3.96 95% CI 3.00–5.23) and in-hospital stroke (OR 10.49 95% CI 8.28–13.29) comparing high to low HFRS.

Conclusions

More than 1 in 20 patients who undergo PCI have intermediate or high risk of frailty which has significantly increased over time. There are poor outcomes and increased inpatient costs associated with greater frailty. Improvements in education of healthcare workers and increased awareness of frailty could facilitate frailty-tailored care to minimise risk of adverse outcomes and its associated costs.

Acknowledgement/Funding

Research and Development Department at the Royal Stoke Hospital, Keele University and Biosensors International

Mode of presentation and mortality amongst patients hospitalized with heart failure? A report from the First Euro Heart Failure Survey

BACKGROUND

Heart failure is heterogeneous in aetiology, pathophysiology, and presentation. Despite this diversity, clinical trials of patients hospitalized for HF deal with this problem as a single entity, which may be one reason for repeated failures.

METHODS

The first EuroHeart Failure Survey screened consecutive deaths and discharges of patients with suspected heart failure during 2000-2001. Patients were sorted into seven mutually exclusive hierarchical presentations: (1) with cardiac arrest/ventricular arrhythmia; (2) with acute coronary syndrome; (3) with rapid atrial fibrillation; (4) with acute breathlessness; (5) with other symptoms/signs such as peripheral oedema; (6) with stable symptoms; and (7) others in whom the contribution of HF to admission was not clear.

RESULTS

The 10,701 patients enrolled were classified into the above seven presentations as follows: 260 (2%), 560 (5%), 799 (8%), 2479 (24%), 1040 (10%), 703 (7%), and 4691 (45%) for which index-admission mortality was 26%, 20%, 10%, 8%, 6%, 6%, and 4%, respectively. Compared to those in group 7, the hazard ratios for death during the index admission were 4.9 (p ≤ 0.001), 4.0 (p < 0.001), 2.2 (p < 0.001), 2.1 (p < 0.001), 1.4 (p < 0.04) and 1.4 (p = 0.04), respectively. These differences were no longer statistically significant by 12 weeks.

CONCLUSION

There is great diversity in the presentation of heart failure that is associated with very different short-term outcomes. Only a minority of hospitalizations associated with suspected heart failure are associated with acute breathlessness. This should be taken into account in the design of future clinical trials.

Soft drinks and sweetened beverages and the risk of cardiovascular disease and mortality: a systematic review and meta-analysis

BACKGROUND

Soft drink consumption is associated with adverse health behaviours that predispose to adverse cardiovascular risk factor profiles; however, it is unclear whether their intake independently leads to an increased risk of cardiovascular events and mortality. We conducted a systematic review and meta-analysis to evaluate this.

METHODS

Medline and EMBASE were searched in July 2015 for studies that considered soft drink intake and risk of mortality, myocardial infarction (MI) or stroke. Pooled risk ratios (RRs) for adverse outcomes were calculated using inverse variance with a random effects model, and heterogeneity was assessed using the I² statistic.

RESULTS

A total of seven prospective cohort studies with 308,420 participants (age range 34-75 years) were included in the review. The pooled results suggest a greater risk of stroke (RR 1.13, 95% CI 1.02-1.24), and MI (RR 1.22, 95% CI 1.14-1.30), but not vascular events with incremental increase in sugar-sweetened beverage (SSB) consumption. With incremental increase in artificially sweetened beverage (ASB) consumption, there was a greater risk of stroke (RR 1.08, 95% CI 1.03-1.14), but not vascular events or MI. In the evaluation of high vs. low SSB, there was a greater risk of MI (RR 1.19, 95% CI 1.09-1.31) but not stroke, vascular events or mortality. For ASB, there was a significantly greater risk of stroke (RR 1.14, 95% CI 1.04-1.26) and vascular events (RR 1.44, 95% CI 1.02-2.03) but not MI or mortality.

CONCLUSIONS

Our results suggest an association between consumption of sugar-sweetened and ASBs and cardiovascular risk, although consumption may be a surrogate for adverse health behaviours.

Habitual chocolate consumption and the risk of incident heart failure among healthy men and women

BACKGROUND

We aimed to examine the association between chocolate intake and the risk of incident heart failure in a UK general population. We conducted a systematic review and meta-analysis to quantify this association.

METHODS AND RESULTS

We used data from a prospective population-based study, the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort. Chocolate intake was quantified based on a food frequency questionnaire obtained at baseline (1993-1997) and incident heart failure was ascertained up to March 2009. We supplemented the primary data with a systematic review and meta-analysis of studies which evaluated risk of incident heart failure with chocolate consumption. A total of 20,922 participants (53% women; mean age 58 ± 9 years) were included of whom 1101 developed heart failure during the follow up (mean 12.5 ± 2.7 years, total person years 262,291 years). After adjusting for lifestyle and dietary factors, we found 19% relative reduction in heart failure incidence in the top (up to 100 g/d) compared to the bottom quintile of chocolate consumption (HR 0.81 95%CI 0.66-0.98) but the results were no longer significant after controlling for comorbidities (HR 0.87 95%CI 0.71-1.06). Additional adjustment for potential mediators did not attenuate the results further. We identified five relevant studies including the current study (N = 75,408). The pooled results showed non-significant 19% relative risk reduction of heart failure incidence with higher chocolate consumption (HR 0.81 95%CI 0.66-1.01).

CONCLUSIONS

Our results suggest that higher chocolate intake is not associated with subsequent incident heart failure.

Prognostic indices for early mortality in ischaemic stroke - meta-analysis

OBJECTIVES

Several models have been developed to predict mortality in ischaemic stroke. We aimed to evaluate systematically the performance of published stroke prognostic scores.

METHODS

We searched MEDLINE and EMBASE in February 2014 for prognostic models (published between 2003 and 2014) used in predicting early mortality (<6 months) after ischaemic stroke. We evaluated discriminant ability of the tools through meta-analysis of the area under the curve receiver operating characteristic curve (AUROC) or c-statistic. We evaluated the following components of study validity: collection of prognostic variables, neuroimaging, treatment pathways and missing data.

RESULTS

We identified 18 articles (involving 163 240 patients) reporting on the performance of prognostic models for mortality in ischaemic stroke, with 15 articles providing AUC for meta-analysis. Most studies were either retrospective, or post hoc analyses of prospectively collected data; all but three reported validation data. The iSCORE had the largest number of validation cohorts (five) within our systematic review and showed good performance in four different countries, pooled AUC 0.84 (95% CI 0.82-0.87). We identified other potentially useful prognostic tools that have yet to be as extensively validated as iSCORE - these include SOAR (2 studies, pooled AUC 0.79, 95% CI 0.78-0.80), GWTG (2 studies, pooled AUC 0.72, 95% CI 0.72-0.72) and PLAN (1 study, pooled AUC 0.85, 95% CI 0.84-0.87).

CONCLUSIONS

Our meta-analysis has identified and summarized the performance of several prognostic scores with modest to good predictive accuracy for early mortality in ischaemic stroke, with the iSCORE having the broadest evidence base.

Influenza, influenza-like symptoms and their association with cardiovascular risks: a systematic review and meta-analysis of observational studies

AIMS

To synthesise the evidence relating influenza and influenza-like symptoms to the risks of myocardial infarction (MI), heart failure (HF) and stroke.

METHODS

We conducted a systematic review and meta-analysis of the evidence relating influenza and influenza-like symptoms to the risks of MI, HF and stroke. We systematically searched all MEDLINE and EMBASE entries up to August 2014 for studies of influenza vs. the cardiovascular outcomes above. We conducted random effects meta-analysis using inverse variance method for pooled odds ratios (OR) and evaluated statistical heterogeneity using the I(2) statistic.

RESULTS

We identified 12 studies with a total of 84,003 participants. The pooled OR for risk of MI vs. influenza (serologically confirmed) was 1.27 (95% CI, confidence interval 0.54-2.95), I(2)  = 47%, which was significant for the only study that adjusted for confounders (OR 5.50, 95% CI 1.31-23.13). The pooled OR for risk of MI vs. influenza-like symptoms was 2.17 (95% CI 1.68-2.80), I(2)  = 0%, which was significant for both unadjusted (OR 2.23, 95% CI 1.65-3.01, five studies) and adjusted studies (OR 2.01, 95% CI 1.24-3.27, two studies). We found one study that evaluated stroke risk, one study in patients with HF, and one that evaluated mortality from MI - all of these studies suggested increased risks of events with influenza-like symptoms.

CONCLUSIONS

There is an association between influenza-like illness and cardiovascular events, but the relationship is less clear with serologically diagnosed influenza. We recommend renewed efforts to apply current clinical guidelines and maximise the uptake of annual influenza immunisation among patients with cardiovascular diseases, to decrease their risks of MI and stroke.

The SOAR stroke score predicts hospital length of stay in acute stroke: an external validation study

AIMS

The objective of this study is to externally validate the SOAR stroke score (Stroke subtype, Oxfordshire Community Stroke Project Classification, Age and prestroke modified Rankin score) in predicting hospital length of stay (LOS) following an admission for acute stroke.

METHODS

We conducted a multi-centre observational study in eight National Health Service hospital trusts in the Anglia Stroke & Heart Clinical Network between September 2008 and April 2011. The usefulness of the SOAR stroke score in predicting hospital LOS in the acute settings was examined for all stroke and then stratified by discharge status (discharged alive or died during the admission).

RESULTS

A total of 3596 patients (mean age 77 years) with first-ever or recurrent stroke (92% ischaemic) were included. Increasing LOS was observed with increasing SOAR stroke score (p < 0.001 for both mean and median) and the SOAR stroke score of 0 had the shortest mean LOS (12 ± 20 days) while the SOAR stroke score of 6 had the longest mean LOS (26 ± 28 days). Among patients who were discharged alive, increasing SOAR stroke score had a significantly higher mean and median LOS (p < 0.001 for both mean and median) and the LOS peaked among patients with score value of 6 [mean (SD) 35 ± 31 days, median (IQR) 23 (14-48) days]. For patients who died as in-patient, there was no significant difference in mean or median LOS with increasing SOAR stroke score (p = 0.68 and p = 0.79, respectively).

CONCLUSION

This external validation study confirms the usefulness of the SOAR stroke score in predicting LOS in patients with acute stroke especially in those who are likely to survive to discharge. This provides a simple prognostic score useful for clinicians, patients and service providers.

TIA, stroke and orthostatic hypotension: a disease spectrum related to ageing vasculature?

AIMS

We sought to identify the determinants of orthostatic hypotension (OH) among patients referred to the transient ischaemic attack (TIA) clinic.

METHODS

We conducted a retrospective analysis of prospectively collected data on patients who attended the TIA clinic in a UK hospital between January 2006 and September 2009. Each patient had their supine and standing or sitting blood pressure measured. Logistic regression was used to estimate the univariate and multivariate odds of OH for the subgroups of patients based on their diagnosis. A 10% significance level for the univariate analysis was used to identify variables in the multivariate model.

RESULTS

A total of 3222 patients were studied of whom 1131 had a TIA, 665 a stroke and 1426 had other diagnoses. The prevalence of either systolic or diastolic OH in the TIA, stroke and patients with other diagnoses was similar being 22% (n = 251), 24% (n = 162) and 20% (n = 292), respectively. Multivariate analyses showed age, prior history of TIA, and diabetes were independently significantly associated with systolic OH alone or diastolic OH alone or either systolic or diastolic OH [ORs 1.03 (1.02-1.05); 1.56 (1.05-2.31); 1.65 (1.10-2.47), respectively]. Among the patients with the diagnosis of stroke, peripheral vascular disease (PVD) was significantly associated with increased odds of OH (3.56, 1.53-8.31), whereas male gender had a significantly lower odds of OH (0.61, 0.42-0.88). In patients with other diagnoses, age (1.04, 1.02-1.05) and diabetes (1.47, 1.04-2.09) were associated with OH, whereas male gender was (0.76, 0.58-1.00) not associated with OH.

CONCLUSION

Orthostatic hypotension is prevalent among patients presenting to TIA clinic. Previous history of vascular disease (prior TIA/stroke/PVD) appears to be a significant associate of OH in this patient population.

Chronic obstructive pulmonary disease and mortality from pneumonia: meta-analysis

BACKGROUND

We aimed to determine whether patients with concomitant community-acquired pneumonia (CAP) and chronic obstructive pulmonary disease (COPD) are at greater risk of death when compared with those with CAP or acute COPD exacerbation alone. We also assessed the effect of inhaled corticosteroids (ICS) on pneumonia mortality in COPD.

METHODS

We searched MEDLINE and EMBASE from inception to March 2012 for studies reporting on mortality in patients with COPD and CAP. We assessed ascertainment of disease, mortality, drug exposure and adjustment for confounders. Data were pooled using random effects meta-analysis, and heterogeneity was estimated using I².

RESULTS

We identified 24 eligible articles overall. Evaluation of 13 studies revealed considerable heterogeneity and a non-significant mortality risk associated with concomitant COPD and CAP as compared with CAP in five studies that reported adjusted or severity-matched data, pooled RR 1.44 (95% CI 0.97-2.16, I² = 50%). There was also considerable inconsistency amongst the effect estimates from five studies that reported on the associated mortality with concomitant CAP and COPD as compared with acute COPD exacerbations alone. Evaluation of six datasets found that ICS use in COPD was not consistently associated with lower mortality in CAP. Reports of reduced mortality with prior ICS use stemmed from three studies that enrolled participants from the same healthcare database.

CONCLUSIONS

Evidence on associated mortality risk with concomitant CAP and COPD (as opposed to CAP alone, or COPD exacerbation alone) is weak and heterogeneous. ICS use was not consistently associated with reduced mortality from pneumonia.

Measures used to treat contrast-induced nephropathy: overview of reviews

OBJECTIVES

Despite many interventions that have been tried, controversy remains regarding the efficacy of interventions for contrast-induced nephropathy (CIN), so we aimed to evaluate the best evidence from recent meta-analyses.

METHODS

We searched MEDLINE, EMBASE and the Cochrane library for interventions which have been used for CIN. We included only the most recent meta-analysis of each intervention. We extracted data on the methodology, quality and results of each meta-analysis. We performed narrative synthesis and adjusted indirect comparison of interventions that were shown to be statistically significant compared with a placebo.

RESULTS

We included 7 systematic reviews and meta-analyses involving 9 different interventions for CIN, with a total of 15 976 participants. A significantly decreased risk of CIN was reported in meta-analysis of the following interventions: N-acetylcysteine [odds ratio (OR) 0.65, 95% confidence interval (CI) 0.48-0.88, I(2)=64%], theophylline [relative risk (RR) 0.48, 95% CI 0.26-0.89, I(2)=44%], statins (RR 0.51, 95% CI 0.34-0.77, I(2)=0%) and sodium bicarbonate (RR 0.62, 95% CI 0.45-0.86, I(2)=49%). Furosemide was shown to increase the risk of CIN (RR 3.27, 95% CI 1.48-7.26, I(2)=0%). Other interventions such as renal replacement therapy, angiotensin-converting enzyme inhibitors, dopamine and fenoldapam failed to show any significant difference from the control group.

CONCLUSION

Although there is some evidence to suggest that N-acetylcysteine, theophylline, sodium bicarbonate and statins may reduce incidence of CIN, limitations in the study quality and heterogeneity preclude any firm recommendations.

ADVANCES IN KNOWLEDGE

N-acetylcysteine, theophylline, sodium bicarbonate and statins show some promise as potentially efficacious agents for preventing CIN, but more high-quality studies are needed before they can be recommended for use in routine practice.

Dabigatran and rivaroxaban for prevention of venous thromboembolism--systematic review and adjusted indirect comparison

WHAT IS KNOWN AND OBJECTIVE

Dabigatran and rivaroxaban are new oral anticoagulants for thromboprophylaxis after elective orthopaedic surgery. We aimed to systematically compare their relative benefits and harms through meta-analysis, and adjusted indirect comparison.

METHODS

We searched PubMed, EMBASE, trial registries and regulatory documents through May 2009 for randomized controlled trials (RCTs) of dabigatran (150 and 220 mg daily) and rivaroxaban (10 mg daily) compared with enoxaparin (40-60 mg daily) in elective orthopaedic surgery. We used random effects meta-analysis to calculate pooled relative risks (RRs) and 95% confidence intervals (95% CI) for the outcomes of total venous thromboembolism, VTE (deep venous thrombosis, non-fatal pulmonary embolism and all-cause mortality), and haemorrhagic adverse events (major and clinically relevant non-major bleeds). Adjusted indirect comparison was used for the pooled RRs of dabigatran and rivaroxaban with enoxaparin as the common control.

RESULTS

Rivaroxaban was superior to enoxaparin for the prevention of venous thromoboembolism (RR 0.56, 95% CI 0.43-0.73, P<0.0001), with a trend for increased haemorrhage (RR 1.26, 95% CI 0.94-1.69, P=0.13). Dabigatran was not superior to enoxaparin for prevention of VTE (RR 1.12, 95% 0.97-1.29, P=0.12), and did not reduce haemorrhage risk (RR 1.10, 95% 0.90-1.35, P=0.32). Adjusted indirect comparison showed that rivaroxaban was superior to dabigatran in preventing VTE, RR 0.50 (95% CI 0.37-0.68), but with a slight trend towards increased haemorrhage RR 1.14 (95% CI 0.80-1.64).

WHAT IS NEW AND CONCLUSION

Rivaroxaban may be more effective than dabigatran for prevention of VTE after elective orthopaedic surgery but might also slightly increase the risk of haemorrhage.

Dissemination and publication of research findings: an updated review of related biases

OBJECTIVES

To identify and appraise empirical studies on publication and related biases published since 1998; to assess methods to deal with publication and related biases; and to examine, in a random sample of published systematic reviews, measures taken to prevent, reduce and detect dissemination bias.

DATA SOURCES

The main literature search, in August 2008, covered the Cochrane Methodology Register Database, MEDLINE, EMBASE, AMED and CINAHL. In May 2009, PubMed, PsycINFO and OpenSIGLE were also searched. Reference lists of retrieved studies were also examined.

REVIEW METHODS

In Part I, studies were classified as evidence or method studies and data were extracted according to types of dissemination bias or methods for dealing with it. Evidence from empirical studies was summarised narratively. In Part II, 300 systematic reviews were randomly selected from MEDLINE and the methods used to deal with publication and related biases were assessed.

RESULTS

Studies with significant or positive results were more likely to be published than those with non-significant or negative results, thereby confirming findings from a previous HTA report. There was convincing evidence that outcome reporting bias exists and has an impact on the pooled summary in systematic reviews. Studies with significant results tended to be published earlier than studies with non-significant results, and empirical evidence suggests that published studies tended to report a greater treatment effect than those from the grey literature. Exclusion of non-English-language studies appeared to result in a high risk of bias in some areas of research such as complementary and alternative medicine. In a few cases, publication and related biases had a potentially detrimental impact on patients or resource use. Publication bias can be prevented before a literature review (e.g. by prospective registration of trials), or detected during a literature review (e.g. by locating unpublished studies, funnel plot and related tests, sensitivity analysis modelling), or its impact can be minimised after a literature review (e.g. by confirmatory large-scale trials, updating the systematic review). The interpretation of funnel plot and related statistical tests, often used to assess publication bias, was often too simplistic and likely misleading. More sophisticated modelling methods have not been widely used. Compared with systematic reviews published in 1996, recent reviews of health-care interventions were more likely to locate and include non-English-language studies and grey literature or unpublished studies, and to test for publication bias.

CONCLUSIONS

Dissemination of research findings is likely to be a biased process, although the actual impact of such bias depends on specific circumstances. The prospective registration of clinical trials and the endorsement of reporting guidelines may reduce research dissemination bias in clinical research. In systematic reviews, measures can be taken to minimise the impact of dissemination bias by systematically searching for and including relevant studies that are difficult to access. Statistical methods can be useful for sensitivity analyses. Further research is needed to develop methods for qualitatively assessing the risk of publication bias in systematic reviews, and to evaluate the effect of prospective registration of studies, open access policy and improved publication guidelines.

Meta-analysis: the effects of proton pump inhibitors on cardiovascular events and mortality in patients receiving clopidogrel

BACKGROUND

Recent studies have suggested an adverse interaction between proton pump inhibitors (PPI) and clopidogrel.

AIM

To perform a meta-analysis of cardiovascular outcomes and mortality in patients taking clopidogrel, with and without concomitant PPI.

METHODS

We searched MEDLINE, EMBASE, Cochrane Controlled Trials Register in October 2009, and checked conference abstracts for randomized and nonrandomized studies that reported the risk of cardiovascular events and mortality with PPI exposure in patients taking clopidogrel. We performed random effects meta-analysis, stratified by study design and assessed heterogeneity using the I2 statistic.

RESULTS

Our review included 23 studies covering 93,278 patients. There was substantial heterogeneity in the meta-analyses of major cardiovascular events (19 studies, I2 = 79%) or myocardial infarction (12 studies, I2 = 77%). Analysis of propensity-matched or randomized trial participants showed no associated cardiovascular risk with PPIs, whereas other observational studies generally showed a significant association. Meta-analysis of 13 studies showed no significant association between PPI use and overall mortality (RR 1.09, 95% CI: 0.94-1.26, P = 0.23, I2 = 60%).

CONCLUSION

As there are conflicting and inconsistent data regarding the adverse clopidogrel-PPI interaction, clinicians should focus on potential harm from ulcers/haemorrhage before deciding to omit PPIs in patients taking clopidogrel.

Application of high-resolution radiochromic film dosimetry in verifying a small-field stereotactic radiosurgery plan

A high-resolution radiochromic film dosimetry (Hr-RCFD) method has been applied to verify a small-field stereotactic radiosurgery (SRS) plan. This was done by exposing a RCF in a Perspex head phantom undergoing the same treatment plan as the patient. The dose distribution obtained by the Hr-RCFD was verified against that calculated by the stereotactic treatment planning system and the result was satisfactory. The Hr-RCFD method has been found to be an accurate and practical tool in verifying small-field SRS plans.

Dual-peak dose measurement for radiochromic films by a newly developed spectral microdensitometer

Radiochromic film (RCF) dosimetry is usually based on densitometric methods which use an analyzing light source of a fixed or a broad spectrum of wavelengths. These methods have not exploited the sensitivity of the dose response of the RCF otherwise attainable by using a light source with wavelengths peaked at the two absorption peaks in the absorption spectrum of the RCF. A new algorithm of dual-peak dose measurement for the RCF has been proposed in this paper to make use of these dual absorption peaks to achieve the maximum attainable sensitivity. This technique relies on the measurement of the transmittance of the RCF at the wavelength of the major and minor absorption peaks, respectively. The dual-peak dose measurement is accomplished with the aid of a novel spectral microdensitometer developed in our Institute. The microdensitometer utilizes a monochromator to provide a light source of which the wavelength can be matched precisely to the wavelength of the absorption peaks of the RCF. The doses obtained at these wavelengths are fed into a weighted objective function and an optimum dose is searched by minimizing the objective function to give the best estimate of the dose deposited on the film. An initial test shows that there is a good agreement between the estimated and actual dose deposited; and the maximum discrepancy was found to be less than 1%.

Development and initial evaluation of a spectral microdensitometer for analysing radiochromic films

Radiation dose deposited on a radiochromic film is considered as a dose image. A precise image extraction system with commensurate capabilities is required to measure the transmittance of the image and translate it to radiation dose. This paper describes the development of a spectral microdensitometer which has been designed to achieve this goal under the conditions of (a) the linearity and sensitivity of the dose response curve of the radiochromic film being highly dependent on the wavelength of the analysing light, and (b) the inherent high spatial resolution of the film. The microdensitometer consists of a monochromator which provides an analysing light of variable wavelength, a film tray on a high-precision scanning stage, a transmission microscope coupled to a thermoelectrically cooled CCD camera, a microcomputer and corresponding interfaces. The measurement of the transmittance of the radiochromic film is made at the two absorption peaks with maximum sensitivities. The high spatial resolution of the instrument, of the order of micrometres, is achieved through the use of the microscope combined with a measure-and-step technique to cover the whole film. The performance of the instrument in regard to the positional accuracy, system reproducibility and dual-peak film calibration was evaluated. The results show that the instrument fulfils the design objective of providing a precise image extraction system for radiochromic films with micrometre spatial resolution and sensitive dose response.

Surface modification of polymers with self-assembled molecular structures: multitechnique surface characterization

A simple, one-step procedure for generating ordered, crystalline methylene chains on polymeric surfaces via urethane linkages was developed. The reaction of dodecyl isocyanate with surface hydroxyl functional groups, catalyzed by dibutyltin dilaurate, formed a predominantly all-trans, crystalline structure on a cross-linked poly(2-hydroxyethyl methacrylate) (pHEMA) substrate. Allophanate side-branching reactions were not observed. Both X-ray photoelectron spectrocopy and time-of-flight secondary ion mass spectrometry show that the surface reaction reached saturation after 30 min at 60 degrees C. Unpolarized Fourier transform infrared-attenuated total reflection showed that, after 30 min, the stretching frequencies, vCH2,asym and vCH2,sym, decreased and approached 2920 and 2850 cm-1, indicative of a crystalline phase. The distance between two hydroxyl groups is roughly 4 A. A tilt angle of 33.5 degrees +/- 2.4 degrees was estimated by dichoric ratios measured in polarized ATR according to the two-phase and Harrick thin film approximations. The findings reported here are significant in that the possibilities for using structures similar to self-assembled monolayers (SAMs) are expanded beyond the rigid gold and silicon surfaces used through most of the literature. Thus, SAMs, biomimetics for ordered lipid cell wall structures, can be applied to real-world biomedical polymers to modify biological interactions. The terminal groups of the SAM-like structure can be further functionalized with biomolecules or antibodies to develop surface-based diagnostics, biosensors, or biomaterials.

Self-assembled molecular structures as ultrasonically-responsive barrier membranes for pulsatile drug delivery

Noninvasive ultrasound has been shown to increase the release rate on demand from drug delivery systems; however, such systems generally suffer from background drug leaching. To address this issue, a drug-containing polymeric monolith coated with a novel ultrasound-responsive coating was developed. A self-assembled molecular structure coating based on relatively impermeable, ordered methylene chains forms an ultrasound-activated on-off switch in controlling drug release on demand, while keeping the drug inside the polymer carrier in the absence of ultrasound. The orderly structure and molecular orientation of these C12 n-alkyl methylene chains on polymeric surfaces resemble self-assembled monolayers on gold. Their preparation and characterization have been published recently (Kwok et al. [Biomacromolecules 2000;1(1):139-148]). Ultrasound release studies showed that a copolymer of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate (MW 400) coated with such an ultrasound-responsive membrane maintained sufficient insulin for multiple insulin delivery, compared with a substantial burst release during the first 2 h from uncoated samples. With appropriate surface coating coverage, the background leach rate can be precisely controlled. The biological activity of the insulin releasate was tested by assessing its ability to regulate [C14]-deoxyglucose uptake in 3T3-L1 adipocyte cells in a controlled cell culture environment. Uptake triggered by released insulin was comparable to that of the positive insulin control. The data demonstrate that the released insulin remains active even after the insulin had been exposed to matrix synthesis and the methylene chain coating process.

ROC curve analysis of lesion detectability on phantoms: comparison of digital spot mammography with conventional spot mammography

Although conventional screen--film mammography has excellent spatial resolution and is commonly used as a screening tool, certain inherent limitations prevent its further improvement. New digital mammography techniques, despite lower spatial resolution than screen--film mammography, may overcome these limitations. This study compared lesion detectability between charge coupled device-based digital spot mammography and conventional spot mammography. A total of 100 sets of images of specially designed breast phantoms was acquired, with variable background achieved by overlapping several layers of grapefruit fibre on a 4 cm thick lucite slab, using both modalities. 75 sets were "normal" images and 25 sets were images with simulated lesions. Four radiologists assessed the images according to a five-point confidence scale. The results were used to construct receiver operating characteristic curves. No statistical difference was observed between the two sets of curves for individual radiologists as well as pooled data. The lower spatial resolution of digital mammography was compensated for by its higher contrast sensitivity relative to conventional spot mammography.

Gadolinium prevents stretch-mediated contractile dysfunction in isolated papillary muscles

We tested the hypothesis that overstretching the myocardium could induce and/or exacerbate contractile dysfunction via stretch-activated (SA) ion channels. Maximum developed tension (T(max)), normalized to a control value, was compared in guinea pig papillary muscles held at one of three resting lengths (physiological stretch, overstretch, and unloaded) for 85 min. Overstretched muscles exhibited decreased contractile force (T(max) = 0.77 +/- 0.03) compared with physiological and unloaded muscles (T(max) = 0.93 +/- 0.05 and 1.03 +/- 0.07, respectively). Gd(3+), an SA channel antagonist, eliminated the adverse effect of overstretching (T(max) = 0.98 +/- 0.06), but nifedipine, a dihydropyridine (DHP) antagonist of L-type calcium channels, did not (T(max) = 0.82 +/- 0.04). Exposure to modified hypoxia-reoxygenation (MHR) during physiological stretch resulted in decreased contractility (T(max) = 0.63 +/- 0.07), an effect that was exacerbated by overstretching (T(max) = 0.44 +/- 0.04). Gd(3+) mitigated the effects of overstretch during MHR (T(max) = 0.64 +/- 0.05), but DHP did not (T(max) = 0.48 +/- 0.04). These data suggest that overstretching of the myocardium contributes to contractile abnormalities via SA channels that are distinct from L-type calcium channels.

Monte Carlo simulation of x-ray spectra in mammography

A model for generating x-ray spectra in mammography is presented. This model used the ITS version 3 Monte Carlo code for simulating the radiation transport. Various target/filter combinations such as tungsten/aluminium, molybdenum/molybdenum, molybdenum/rhodium and rhodium/rhodium were used in the simulation. Both bremsstrahlung and characteristic x-ray production were included in the model. The simulated x-ray emission spectra were compared with two sets of spectra, those of Boone et al (1997 Med. Phys. 24 1863-74) and IPEM report 78. The chi2 test was used for the overall goodness of fit of the spectral data. There is good agreement between the simulated x-ray spectra and the comparison spectra as the test yielded a probability value of nearly 1. When the transmitted x-ray spectra for specific target/filter combinations were generated and compared with a measured molybdenum/rhodium spectrum and spectra generated in IPEM report 78, close agreement is also observed. This was demonstrated by the probability value for the chi2 test being almost 1 for all the cases. However, minor differences between the simulated spectra and the 'standard' ones are observed.

Chemical conjugation of a novel antibody-interleukin 2 immunoconjugate against c-erbB-2 product

OBJECTIVE

To develop a new chemical method to produce a monoclonal antibody (MoAb) 520C9/recombinant human interleukin 2 (rhIL-2) conjugate.

METHODS

MoAb 520C9 reactive with the protooncogene c-erbB-2 product P185 was chemically conjugated with rhIL-2 by using a simple two-step method. First, the rhIL-2 was activated by Sulfosuccinimidyl 4-[N-maleimidomethyl] cyclohexane-1-carboxylate, a heterobifunctional linker, and N-succinimidyl s-acetylthioacetate was introduced onto 520C9. Then SATA on the 520C9 was reacted with the maleimide group on the activated rhIL-2 to generate 520C9-rhIL-2 immunoconjugate.

RESULTS

The immunoconjugate retained the antigen binding activity compared to the respective native antibody as determined by an indirect live cell binding assay. The immunoconjugate also possessed IL-2 activity as measured by the standard CTLL-2 cells proliferation assay and the stimulation of human peripheral blood mononuclear cells (PBMCs) into lymphokine-activated killer cells.

CONCLUSION

Our method of conjugation of rhIL-2 to 520C9 preserves the binding activity of the antibody and the cytokine function of IL-2. This simple and efficient method of conjugation should be applicable to other types of MoAbs and recombinant cytokines.

Design of infection-resistant antibiotic-releasing polymers. II. Controlled release of antibiotics through a plasma-deposited thin film barrier

In the first paper in this series, we described the methods to synthesize an antibacterial polyurethane (PU) incorporating ciprofloxacin as the releasable antibiotic and poly(ethylene glycol) as the pore-forming agent. Here, we report that a thin, RF-plasma-deposited, n-butyl methacrylate (BMA) overlayer on this drug-loaded PU can act as a rate-limiting barrier to achieve a constant, sustained release of ciprofloxacin. Deposition power and deposition time during the coating process were optimized to give an appropriate crosslinked coating barrier that yielded desirable release rates, above the minimum required killing rate, N(kill). Electron spectroscopy for chemical analysis (ESCA), also known as X-ray photoelectron spectroscopy (XPS), was used to characterize the coating, and its crosslinking degree was indirectly related to the C/O ratio. Increasing either deposition power (10-60 W) or duration (5-25 min) resulted in increased C/O ratios and decreased ciprofloxacin release rates. The correlation between increased C/O ratios and reduced release rates is believed to be due to the increased crosslinking, increased hydrophobicity and increased thickness of the coating. The optimal plasma conditions to attain an appropriate crosslinked plasma-deposited film (PDF) required argon etching, pre-treatment of the matrices with an 80W-BMA plasma for 1 min, followed by immediate BMA plasma deposition at 40 W and 150 mT for 20 min. By using these plasma deposition protocols, we eliminated the initial burst effect, significantly reduced the release rates, and closely approached the zero order release kinetics for at least five days. In this study, we also showed that ESCA could be used as a powerful tool to explain the release behavior of molecules through the plasma-deposited films (PDFs).

Design of infection-resistant antibiotic-releasing polymers: I. Fabrication and formulation

Biomaterials-related infections are often observed with prosthetic implants and in many cases result in the failure of the devices. To design a biomedically useful polymer that is intrinsically infection-resistant, we have developed a ciprofloxacin-loaded polyurethane (PU) matrix that releases antibiotic locally at the implant surface, thereby minimizing bacterial accumulation. We report here the methods of fabrication and formulation for making such antibiotic-loaded devices, as well as evidence of their bactericidal properties. Specifically, various pore-forming agents and drug loadings were examined. An optimum formulation consisting of BIOSPAN PU, poly(ethylene glycol) and ciprofloxacin offered the longest effective period of sustained release (5 days). The bactericidal efficacy of the released ciprofloxacin against Pseudomonas aeruginosa (PA) was four times that of the control PU without antibiotics. This bactericidal efficiency was due to an increase in the PA detachment from the surface. These observations suggested that the released ciprofloxacin was biologically active in preventing the bacteria from permanently adhering to the substratum, and thus decreasing the possibility of biofilm-related infection.

Study of hygroscopic properties of aqueous mixtures of disodium fluorescein and sodium chloride using an electrodynamic balance

PURPOSE

The purposes of this study are: a) to demonstrate the use of an Electrodynamic Balance (EDB) to investigate the hygroscopic properties of pharmaceutical aerosols; and b) to evaluate the applicability of the Zdanovskii-Stokes-Robinson model (ZSR) in the associated data analysis with multicomponent pharmaceutical aerosols.

METHODS

The compositional dependence of the water activity of two model materials commonly employed in the study of pharmaceutical aerosols, namely, NaCl and Disodium Fluorescein (DF), was investigated using an EDB. The water contents of single levitated droplets of NaCl and DF and their mixtures at mass ratios of 1:3, 1:1, 3:1, and 6:1 from dilute concentration to high supersaturation were determined as a function of relative humidity (RH).

RESULTS

At decreasing ambient RH, supersaturated aqueous NaCl droplets lose water and crystallize to form dry solid particles at an RH of approximately 50%. Aqueous DF droplet continues to lose water until it reaches a final state containing about 20% by mass of residual water. Mixed solutions of DF and NaCl crystallize at an RH of approximately 50% and then continue to lose water at lower RHs. The resulting "dried" particle still contains water whose amount depends on the mass ratios of DF and NaCl in the mixture. Good prediction of water activity of the DF-NaCl mixture can be achieved with the ZSR model. Collection of a full set of water activity-composition data at each mass ratio of DF-NaCl requires only a few hours.

CONCLUSIONS

The EDB, together with the application of the ZSR model in data treatment, appears to be a valuable tool for studying the hygroscopic properties of pharmaceutical aerosols.

Radiolabeling of monoclonal antibody B43.13 with rhenium-188 for immunoradiotherapy

In this study we report a novel method for direct radiolabeling of monoclonal antibody B43.13 (MAb-B43.13) with 188Re and have evaluated the product's radiochemical, biochemical, immunochemical and selected biological properties. 188Re-MAb-B43.13 was readily prepared by the addition of generator produced perrhenate to a preformulated antibody vial after an optimal amount of supplemental stannous ion, in the form of stannous tartrate, was added. The final radiolabeled product retained its biochemical purity (as determined by size-exclusion HPLC and R/NR-SDS-PAGE), its immunoreactivity (as determined by immunoassay) and presented with a typical stability (in the presence of serum and cysteine) and biodistribution (in tumored mice) profile. The evaluation of the product for immunoradiotherapy of ovarian cancer in a clinical setting requires further studies.

Effect of recombinant human interleukin 2 on neutrophil adherence to endothelial cells in vitro

Human neutrophils were demonstrated to possess interleukin-2 receptor (IL-2R) beta and gamma chains, not alpha chain and the binding of IL-2 to the IL-2R beta chain on neutrophils plays an important regulatory role in neutrophil functions. We have investigated in this study the hypothesis that recombinant human IL-2 (rhIL-2) can directly activate human neutrophils and increase their adherence to human umbilical vein endothelial cells (HUVEC). In an in vitro microtiter adherence assay, rhIL-2 significantly stimulated neutrophil adherence to HUVEC in a dose- and time-dependent manner, rhILI-2 concentration at 2000 u/ml and 2 hour incubation gave the best neutrophil stimulation. Treatment of neutrophils with rhIL-2 increased the expression of adhesion molecule CD18. Pretreatment of the stimulated neutrophils with a blocking monoclonal antibody to CD18 decreased but not completely blocked the adherence of neutrophils to HUVEC. These data suggest than rhIL-2 can directly stimulate and increase neutrophil adherence to HUVEC by enhancing the expression of CD18 and possibly other adhesion molecules on neutrophil surface. This may be a critical step in the early stage of the vascular leak syndrome (VLS) associated with high dose IL-2 therapy.

Autoradiography-based, three-dimensional calculation of dose rate for murine, human-tumor xenografts

A Fast Fourier Transform method for calculating the three-dimensional dose rate distribution for murine, human-tumor xenografts is outlined. The required input includes evenly-spaced activity slices which span the tumor. Numerical values in these slices are determined by quantitative 125I autoradiography. For the absorbed dose-rate calculation, we assume the activity from both 131I- and 90Y-labeled radiopharmaceuticals would be distributed as is measured with the 125I label. Two example cases are presented: an ovarian-carcinoma xenograft with an IgG 2ak monoclonal antibody and a neuroblastoma xenograft with meta-iodobenzylguanidine (MIBG). Considering all the volume elements in a tumor, we show, by comparison of histograms and also relative standard deviations, that the measured 125I activity and the calculated 131I dose-rate distributions, are similarly non-uniform and that they are more non-uniform than the calculated 90Y dose-rate distribution. However, the maximum-to-minimum ratio, another measure of non-uniformity, decreases by roughly an order of magnitude from one distribution to the next in the order given above.

A reanalysis of microdosimetric data pertaining to the quality factor of tritium

A recently developed procedure for estimating the quality factor from microdosimetric data is applied to a published experiment involving tritium. Arguments are presented indicating that the observed value is most likely an estimate of a lower limit for this quantity. It is concluded that the data support a value of 2 for the tritium quality factor.

An evaluation of the EGS4 and CYLTRAN Monte Carlo codes with regard to boundary beta-ray dosimetry by comparison with experimental beta-ray dose backscatter factors

Beta-ray dose backscatter factors or dose ratios at planar soft-tissue boundaries were calculated using the EGS4/RESTA and CYLTRAN (version 2.1) Monte Carlo codes and these data were compared with experimental results. Since the beta-ray source was 32P, this work addressed the transport of, and energy deposition by, electrons less energetic than 2 MeV. In particular, the simulations targeted the codes' performances with regard to the transport of low energy electrons across material boundaries and the backscattering of low energy electrons. In general, backscatter factors calculated at 7.25 mg/cm2 from several soft-tissue interfaces agreed with experimental values to within about five percent. CYLTRAN was also used to calculate the variation of backscatter factor with distance from aluminum/soft-tissue and air/soft-tissue interfaces and was found to reproduce the shapes of experimental backscatter factor depth profiles.