Cardiopulmonary bypass changes the plasma proteome in children undergoing tetralogy of Fallot repair

Introduction:

Cardiopulmonary bypass (CPB) can be associated with deleterious clinical effects. However, the impact of CPB on inflammatory, immunological and other homeostatic pathways remains poorly understood. We investigated the impact of CPB on the plasma proteome in children undergoing tetralogy of Fallot repair.

Methods:

Blood samples were taken from 20 children prior to and at the end of CPB and 6h, 12h and 24h after CPB. Plasma was analysed by liquid chromatography-mass spectrometry (LC-MS) in a label-free, untargeted approach. Data were analysed using Genedata software to identify peptides that were differentially expressed (p<0.01 above a false discovery rate). Proteins were identified from peptides that demonstrated differential expression.

Results:

The proteins that were found to be differentially expressed were haptoglobin isoform 1 preproprotein, isoform 2 of semaphorin-6C, vitamin D-binding protein, inter-alpha-trypsin inhibitor, ceruloplasmin, apolipoprotein B100 and fibrinogen alpha.

Conclusion:

CPB alters the plasma proteome with differences most apparent at 6h and 12h post CPB. There was a return to baseline with no proteins differentially regulated by 24h.

Beta (β)-antithrombin activity in children and adults: implications for heparin therapy in infants and children

BACKGROUND

Antithrombin, a hemostatic protein and naturally occurring anticoagulant, is a major thrombin inhibitor. The capacity of antithrombin to inhibit thrombin is known to increase a 1000-fold whilst in the presence of unfractionated heparin. β-antithrombin is an isoform of antithrombin with a high affinity for unfractionated heparin. This study aimed to determine the differences in the anticoagulant activity of the β-antithrombin isoform in children compared with adults.

METHODS

Plasma samples were obtained from 105 healthy individuals from the following age groups: neonates (day 1 and day 3), 28 days to 1 year, 1-5 years, 6-10 years, 11-16 years and adults. The method utilized to measure the activity of β-antithrombin in plasma is a modified version of the total antithrombin assay routinely used in diagnostic laboratories. The modified version of this assay allows for the specific quantification of the β-antithrombin glycoform anticoagulant activity alone, as the β-antithrombin molecule is activated under a high salt concentration, which in turn does not allow activation of other antithrombin isoforms.

CONCLUSIONS

This study demonstrated that there are no age-specific differences in the activity of β-antithrombin. However, considering that the total AT activity is significantly reduced in neonates, our results suggest that in this population β-antithrombin activity is a major contributor to the overall activity of AT.

Developmental hemostasis: age-specific differences in the levels of hemostatic proteins

INTRODUCTION

Developmental hemostasis recognizes the physiologic differences between the hemostatic system of neonates and children and that of adults. As compared with the knowledge of hemostatic system physiology in adults, our understanding in neonates and children remains inadequate. Routine clinical coagulation testing most commonly measures functional parameters of the hemostatic system. Very few studies have measured age-specific levels of hemostatic proteins. An understanding of the normal fluctuations in the levels of hemostatic proteins is vital in the prevention, diagnosis and treatment of hemostatic problems during infancy and childhood. This study was designed as the first comprehensive study of the age-specific changes in the levels of important hemostatic proteins in healthy neonates, children, and adults.

METHODS

Plasma samples were obtained from 120 healthy individuals from the following age groups: neonates (day 1 and day 3), 28 days to 1 year, 1-5 years, 6-10 years, 11-16 years, and adults. Factor II, FV, FVII, FVIII, FIX, FX, FXI, FXII, FXIII, plasminogen, protein C and total and free protein S were quantified with commercially available ELISA kits.

RESULTS

The levels of 10 proteins were significantly different between neonates and adults, and these differences persisted throughout childhood for most of these proteins.

CONCLUSION

The results of this study confirm that the levels of the majority of coagulation proteins vary significantly with age. Future studies should investigate how hemostatic protein level relates to functional changes with age.

The in vitro anticoagulant effect of rivaroxaban in children

INTRODUCTION

Current anticoagulation therapy in children is less than ideal, requiring regular venous monitoring and dosing adjustments. Limitations associated with conventional anticoagulants have prompted the development of novel drugs that specifically target key proteins in the coagulation system. Rivaroxaban is the first oral, direct Factor Xa inhibitor available for the prevention of venous thromboembolism in adults. Its predictable pharmacokinetic profile, high oral bioavailability and once-daily dosing make rivaroxaban an optimal anticoagulant that warrants investigation in children. The aim of this study was to investigate the age-related anticoagulant effect of rivaroxaban in vitro.

MATERIALS AND METHODS

Age-specific plasma pools were created (i.e. 28 days-23 months, 2-6, 7-11, 12-16 years and adults) and spiked with increasing concentrations of rivaroxaban (0-500 ng/ml). Commercially available PT, APTT and anti-Factor Xa assays, as well as sub-sampling thrombin generation assays, were used to measure rivaroxaban effect.

RESULTS

The results of this study indicate that there are no significant differences in rivaroxaban effect across the age groups in vitro.

CONCLUSION

In vivo studies are required to confirm the consistency of dose-response across the paediatric age groups.

Modelled cost-effectiveness of high cut-off haemodialysis compared to standard haemodialysis in the management of myeloma kidney

BACKGROUND

Approximately 10-20% of multiple myeloma patients experience dialysis-dependent renal failure. This is principally due to myeloma kidney, a tubulointerstitial injury caused by high circulating concentrations of monoclonal free light chains. Studies have found that between 3% and 37% of patients with myeloma kidney requiring dialysis recover renal function. In-vivo studies indicate that extended haemodialysis using high cut-off dialysers (HCO-HD) can remove significant quantities of free light chains and is associated with a renal recovery rate of 63-74% in these patients.

OBJECTIVE

The objective of this study was to assess the cost-effectiveness of HCO-HD compared to standard HD in the management of myeloma kidney.

METHODS

The study used a lifetime Excel-based decision tree model that followed all patients from treatment of the initial presentation with myeloma kidney requiring dialysis to death. It was populated with published clinical data, United Kingdom costs and expert opinion, using a National Health Service perspective and 3.5% annual discounting.

RESULTS

HCO-HD was dominant to standard HD, meaning it was both more effective (greater life years and quality adjusted life years) and less costly, due to a greater increase in the proportion of patients recovering renal function. The model projected lifetime costs of £31,345 per patient for patients treated with standard haemodialysis only and £24,845 for the new treatment (discounted). The model predicted an average survival of 19.92 months for patients on standard HD and 33.90 months for the new therapy (discounted).

CONCLUSIONS

The analysis found that treatment of myeloma kidney using an extended schedule of HCO-HD may substantially improve renal recovery in multiple myeloma patients compared to standard HD, resulting in greater life expectancy and cost savings due to avoided chronic dialysis. Limitations of the study include those common to rare diseases including small study sizes and limited natural history data.

Costs associated with erythropoiesis-stimulating agent administration to hemodialysis patients

BACKGROUND

Treatment of anemia in hemodialysis patients usually requires the use of expensive erythropoietic proteins. Cost analyses usually focus on drug acquisition costs. Other costs associated with anemia therapy include resources for anemia monitoring as well as preparation and administration of an erythropoiesis-stimulating agent.

METHODS

The nonacquisition costs associated with subcutaneous administration of epoetin alfa were determined in a Canadian hemodialysis unit. A time-and-motion technique was used to determine the nursing time for preparation and administration. Fixed anemia costs were inventory control, monitoring, blood sampling, and laboratory analysis. Variable costs were those which varied with dosing frequency. The costs are expressed in Canadian dollars (2005).

RESULTS

The mean time associated with preparation and administration was 3.2 min/injection. The annual nonacquisition per patient cost was CAD 2,290.04. Fixed costs were CAD 1,946.01, while the variable costs were CAD 344.03/year. Sensitivity analysis showed a decrease in cost to CAD 1,611.34, if iron monitoring were decreased from monthly to 3 monthly, and to CAD 2,090.66, if patients were converted to less frequent dosing using darbepoetin alfa.

CONCLUSIONS

The nonacquisition costs associated with anemia therapy in hemodialysis patients are considerable. Less frequent monitoring of iron therapy and less frequent dosing could decrease costs by CAD 678.40 and CAD 199.38/patient/year, respectively.

Cost effectiveness of adding ezetimibe to atorvastatin therapy in patients not at cholesterol treatment goal in Canada

INTRODUCTION

This analysis compared the cost effectiveness of adding ezetimibe to atorvastatin therapy versus atorvastatin titration or adding cholestyramine (a resin) for patients at high risk of a coronary artery disease (CAD) event who did not reach target cholesterol levels on their current atorvastatin dosage. The primary analysis focused on 65-year-old patients with low-density lipoprotein cholesterol (LDL-C) levels of 3.1 or 3.6 mmol/L with a treatment goal of <2.5 mmol/L, classified as very high risk according to the 2000 Canadian Guidelines for Management and Treatment of Hyperlipidaemia.

METHODS

A previously developed Markov model was utilised to capture the cost and clinical consequences of lipid-lowering therapy in primary and secondary prevention of CAD. Comparisons between treatment strategies were made using ICERs (cost per QALY) from a Canadian Ministry of Health perspective. The effects of lipid-lowering therapies were based on clinical trial data. The risks of CAD events were estimated using Framingham Heart Study risk equations. Treatment costs and the costs of acute and long-term care for CAD events were included in the analysis. Costs (Canadian dollar, 2002 values) and outcomes were discounted at 5% per annum.

RESULTS

Ezetimibe added to atorvastatin therapy compared with treatment with the most common fixed atorvastatin daily dosage (10 mg) or with common atorvastatin titration strategies (up to 20 mg daily; up to 40 mg daily) resulted in cost per QALY estimates ranging from 25,344 to 44,332 Canadian dollars. The addition of ezetimibe to atorvastatin therapy was less costly and more effective than the addition of cholestyramine (dominant).

CONCLUSION

Our analysis suggests that adding ezetimibe to atorvastatin for patients not achieving treatment goals with their current atorvastatin dose produces greater clinical benefits than treatment with a fixed-dose atorvastatin or atorvastatin titration at an increased overall cost. The cost-effectiveness ratios provide strong evidence for the adoption of ezetimibe within the Canadian healthcare system.

Cost-effectiveness of becaplermin for nonhealing neuropathic diabetic foot ulcers

Foot ulcers secondary to peripheral neuropathy and vascular disease are a commonly occurring complication for people with diabetes. Becaplermin, a genetically-engineered growth factor in a hydrogel vehicle, has been shown to be more effective than vehicle-only control in healing chronic foot ulcers of patients with adequate vasculature receiving best clinical care. To evaluate the cost-effectiveness of adding up to 20 weeks of becaplermin to a regimen of best clinical care, a 1-year decision-analytic model was developed and tested using data from a previously published controlled clinical study involving 251 people with diabetes (124 becaplermin/127 control) and adequate vasculature presenting with an infection-free ulcer that had failed to heal despite appropriate therapy. A 20-week healing rate was estimated based on the clinical trial data assuming becaplermin treatment was terminated at 10 weeks in non-responding ulcers, and follow-up data were extended to 1 year. Resource utilization was estimated by an expert panel using a modified Delphi approach. Using the model, it was found that incorporating becaplermin with best clinical care resulted in 26 fewer ulcer-days per patient per year compared to best clinical care alone with an incremental cost-effectiveness ratio of $6 per ulcer-day averted. Results were sensitive to becaplermin cost, efficacy, and effect on infection and recurrence rates. The clinical benefits of becaplermin deserve further investigation to enhance cost-effectiveness information for informed treatment decisions.

Cost-effectiveness of Apligraf in the treatment of venous leg ulcers

Venous ulcers are the most common chronic wounds of the lower leg. Skin substitutes recently have been introduced to stimulate nonhealing wounds. To conduct an incremental cost-effectiveness analysis, a model was developed to compare the four-layer bandage system, with and without one application of skin substitute, for the outpatient treatment of venous leg ulcers. The model estimated the costs and consequences of treatment with and without the skin substitute application. Two analytic horizons were explored: 3 months and 6 months. Determined by seven physicians, data and assumptions for the 3-month model were based on information from a clinical trial, published studies, and clinical experience. Data for the 6-month model were extrapolated from the shorter model. The model results indicate that over 3 months, the use of the skin substitute provided a benefit of 22 ulcer days averted per patient at an incremental cost of $304 (societal). The incremental cost-effectiveness ratio was $14 per ulcer day averted. Over 6 months, the incremental cost-effectiveness ratio was less than $5 per ulcer-day averted. The skin substitute plus a four-layer bandage was more costly and more effective than the four-layer bandage alone. The skin substitute is increasingly cost-effective over a longer analytic horizon and in a subgroup of patients with ulcers of long duration (greater than 1-year duration at baseline). The results come from a model that is based on a series of estimates and assumptions, and accordingly, confirmation of this finding in a prospective study is encouraged.

A novel method for the evaluation of the severity of nausea and vomiting of pregnancy

The symptomatology of nausea and vomiting of pregnancy (NVP) ranges from mild to very severe. The most advanced method to measure the burden of NVP, the Rhode's scores, incorporates physical signs (length and number of episodes of nausea, number and volume of vomits, and number of retching) with measures of distress caused by these symptoms. However, this system has been validated only for symptoms that occurred in the past 12 h, thus obviating its wide clinical use, and particularly its retrospective use.

OBJECTIVE

To examine whether the severity of the physical symptoms of NVP correlate with the degree of stress caused by them, and to develop simple scores that can be used clinically.

METHODS AND RESULTS

We prospectively scored 283 women with NVP using the Rhode's system. There was excellent and highly significant correlation between the physical symptoms and their degrees of distress. Subsequently, we examined two simple scoring systems, one with three and one with five physical symptoms. Both yielded distribution of severity of NVP not different from the one found with the use of the full Rhode's score.

CONCLUSION

A scoring system based on all five physical symptoms, or only on three (length of nausea, number of episodes of nausea and number of vomits) yielded accurate estimates of severity and changes in severity of NVP. Unlike the Rhode's score, this simple method can be used clinically to evaluate the severity and changes in NVP.

Variation in rheumatologists' and family physicians' perceptions of the indications for and outcomes of knee replacement surgery

OBJECTIVE

To assess agreement among rheumatologists and family physicians (FP) about the indications for knee replacement (KR) referral, use of nonsurgical management options, and perceived outcomes of KR, and to determine the relationship between these opinions and the number of patients seen with severe osteoarthritis (OA) of the knee.

METHODS

98 adult rheumatologists and a random sample of 250 FP in Ontario, Canada were surveyed. Of the practising and traceable rheumatologists and FP, 70.0 and 5.16% responded, respectively.

RESULTS

FP disagreed on how 28 of 32 patient factors affected their KR referral decision, while rheumatologists disagreed on 26 of these 32 factors (p = 0.03). Rheumatologists and FP consistently disagreed on the use of 8 of 10 treatments for knee OA (p = 0.37). While rheumatologists and FP reported similar KR outcomes, FP were less in agreement (p = 0.03). Clinical disagreement for the indications for KR (p < 0.0001) and KR outcomes (p < 0.0001) were greater among FP than among orthopedic surgeons who were surveyed in a prior study. Clinical disagreement about the indications for KR was greater among rheumatologists than among surgeons (p = 0.04), but there was no difference in perceived KR incomes (p = 0.18).

CONCLUSION

Referring physicians disagreed on the indications for KR referral an on the treatments for knee arthritis, but were in general agreement regarding KR outcomes. Clinical disagreement was greater among FP than among rheumatologists, who in turn reported more disagreement than orthopedic surgeons. Explanations for these difference in perceptions should be the focus of research, but guidelines specifically tailored for each physician specialty may be required to reduce clinical uncertainty.