Discontinuation of anti-tumour necrosis factor alpha treatment owing to blood test abnormalities, and cost-effectiveness of alternate blood monitoring strategies

BACKGROUND

There is no evidence base to support the use of 6-monthly monitoring blood tests for the early detection of liver, blood and renal toxicity during established anti-tumour necrosis factor alpha (TNFα) treatment.

OBJECTIVES

To evaluate the incidence and risk factors of anti-TNFα treatment cessation owing to liver, blood and renal side-effects, and to estimate the cost-effectiveness of alternate intervals between monitoring blood tests.

METHODS

A secondary care-based retrospective cohort study was performed. Data from the British Association of Dermatologists Biologic and Immunomodulators Register (BADBIR) were used. Patients with at least moderate psoriasis prescribed their first anti-TNFα treatment were included. Treatment discontinuation due to a monitoring blood test abnormality was the primary outcome. Patients were followed-up from start of treatment to the outcome of interest, drug discontinuation, death, 31 July 2021 or up to 5 years, whichever came first. The incidence rate (IR) and 95% confidence intervals (CIs) of anti-TNFα discontinuation with monitoring blood test abnormality was calculated. Multivariate Cox regression was used to examine the association between risk factors and outcome. A mathematical model evaluated costs and quality-adjusted life years (QALYs) associated with increasing the length of time between monitoring blood tests during anti-TNFα treatment.

RESULTS

The cohort included 8819 participants [3710 (42.1%) female, mean (SD) age 44.76 (13.20) years] that contributed 25 058 person-years (PY) of follow-up and experienced 125 treatment discontinuations owing to a monitoring blood test abnormality at an IR of 5.85 (95% CI 4.91-6.97)/1000 PY. Of these, 64 and 61 discontinuations occurred within the first year and after the first year of treatment start, at IRs of 8.62 (95% CI 6.74-11.01) and 3.44 (95% CI 2.67-4.42)/1000 PY, respectively. Increasing age (in years), diabetes and liver disease were associated with anti-TNFα discontinuation after a monitoring blood test abnormality [adjusted hazard ratios of 1.02 (95% CI 1.01-1.04), 1.68 (95% CI 1.00-2.81) and 2.27 (95% CI 1.26-4.07), respectively]. Assuming a threshold of £20 000 per QALY gained, no monitoring was most cost-effective, but all extended periods were cost-effective vs. 3- or 6-monthly monitoring.

CONCLUSIONS

Anti-TNFα drugs were uncommonly discontinued owing to abnormal monitoring blood tests after the first year of treatment. Extending the duration between monitoring blood tests was cost-effective. Our results produce evidence for specialist society guidance to reduce patient monitoring burden and healthcare costs.

Risk-stratified monitoring for sulfasalazine toxicity: prognostic model development and validation

BACKGROUND

Sulfasalazine-induced cytopenia, nephrotoxicity and hepatotoxicity is uncommon during long-term treatment. Some guidelines recommend 3 monthly monitoring blood tests indefinitely during long-term treatment while others recommend stopping monitoring after 1 year. To rationalise monitoring, we developed and validated a prognostic model for clinically significant blood, liver or kidney toxicity during established sulfasalazine treatment.

DESIGN

Retrospective cohort study.

SETTING

UK primary care. Data from Clinical Practice Research Datalink Gold and Aurum formed independent development and validation cohorts.

PARTICIPANTS

Age ≥18 years, new diagnosis of an inflammatory condition and sulfasalazine prescription.

STUDY PERIOD

1 January 2007 to 31 December 2019.

OUTCOME

Sulfasalazine discontinuation with abnormal monitoring blood-test result.

ANALYSIS

Patients were followed up from 6 months after first primary care prescription to the earliest of outcome, drug discontinuation, death, 5 years or 31 December 2019. Penalised Cox regression was performed to develop the risk equation. Multiple imputation handled missing predictor data. Model performance was assessed in terms of calibration and discrimination.

RESULTS

8936 participants were included in the development cohort (473 events, 23 299 person-years) and 5203 participants were included in the validation cohort (280 events, 12 867 person-years). Nine candidate predictors were included. The optimism adjusted R2 D and Royston D statistic in the development data were 0.13 and 0.79, respectively. The calibration slope (95% CI) and Royston D statistic (95% CI) in validation cohort was 1.19 (0.96 to 1.43) and 0.87 (0.67 to 1.07), respectively.

CONCLUSION

This prognostic model for sulfasalazine toxicity uses readily available data and should be used to risk-stratify blood-test monitoring during established sulfasalazine treatment.

Cost-effectiveness of spinal muscular atrophy newborn screening based on real-world data in Belgium

The objective of the study was to assess the cost-effectiveness of real-world spinal muscular atrophy newborn screening followed by treatment. We modeled the lifetime cost-effectiveness of the spinal muscular atrophy newborn screening followed by treatment (screening) compared to treatment without screening (no screening) from the Belgian healthcare perspective. Real-world data, including quality of life, costs, and motor development data, were collected on 12 patients identified by screening and 43 patients identified by their symptoms. "Screening" was associated with slightly higher healthcare costs (€ 6,858,061 vs. € 6,738,120) but more quality-adjusted life years (QALY) (40.95 vs. 20.34) compared to "no screening", leading to an incremental cost-effectiveness ratio of € 5,820 per QALY gained. "Screening" was dominant from a societal perspective (negative incremental costs: € -14,457; incremental QALY = 20.61), when incorporating the burden on caregivers (negative incremental costs = € -74,353; incremental QALY = 27.51), and when the treatment was chosen by the parents (negative incremental costs = € -2,596,748; incremental QALY = 20.61). Spinal muscular atrophy newborn screening coupled with early treatment is thus cost-effective compared with late treatment following clinical diagnosis and is dominant when societal perspective, caregiver burden, and treatment based on parental preference were considered.

Risk-stratified monitoring for thiopurine toxicity in immune-mediated inflammatory diseases: prognostic model development, validation, and, health economic evaluation

Background

Patients established on thiopurines (e.g., azathioprine) are recommended to undergo three-monthly blood tests for the early detection of blood, liver, or kidney toxicity. These side-effects are uncommon during long-term treatment. We developed a prognostic model that could be used to inform risk-stratified decisions on frequency of monitoring blood-tests during long-term thiopurine treatment, and, performed health-economic evaluation of alternate monitoring intervals.

Methods

This was a retrospective cohort study set in the UK primary-care. Data from the Clinical Practice Research Datalink Aurum and Gold formed development and validation cohorts, respectively. People age ≥18 years, diagnosed with an immune mediated inflammatory disease, prescribed thiopurine by their general practitioner for at-least six-months between January 1, 2007 and December 31, 2019 were eligible. The outcome was thiopurine discontinuation with abnormal blood-test results. Patients were followed up from six-months after first primary-care thiopurine prescription to up to five-years. Penalised Cox regression developed the risk equation. Multiple imputation handled missing predictor data. Calibration and discrimination assessed model performance. A mathematical model evaluated costs and quality-adjusted life years associated with lengthening the interval between blood-tests.

Findings

Data from 5982 (405 events over 16,117 person-years) and 3573 (269 events over 9075 person-years) participants were included in the development and validation cohorts, respectively. Fourteen candidate predictors (21 parameters) were included. The optimism adjusted R2 and Royston D statistic in development data were 0.11 and 0.76, respectively. The calibration slope and Royston D statistic (95% Confidence Interval) in the validation data were 1.10 (0.84-1.36) and 0.72 (0.52-0.92), respectively. A 2-year period between monitoring blood-test was most cost-effective in all deciles of predicted risk but the gain between monitoring annually or biennially reduced in higher risk deciles.

Interpretation

This prognostic model requires information that is readily available during routine clinical care and may be used to risk-stratify blood-test monitoring for thiopurine toxicity. These findings should be considered by specialist societies when recommending blood monitoring during thiopurine prescription to bring about sustainable and equitable change in clinical practice.

Funding

National Institute for Health and Care Research.

Risk stratified monitoring for methotrexate toxicity in immune mediated inflammatory diseases: prognostic model development and validation using primary care data from the UK

OBJECTIVE

To develop and validate a prognostic model to inform risk stratified decisions on frequency of monitoring blood tests during long term methotrexate treatment.

DESIGN

Retrospective cohort study.

SETTING

Electronic health records within the UK's Clinical Practice Research Datalink (CPRD) Gold and CPRD Aurum.

PARTICIPANTS

Adults (≥18 years) with a diagnosis of an immune mediated inflammatory disease who were prescribed methotrexate by their general practitioner for six months or more during 2007-19.

MAIN OUTCOME MEASURE

Discontinuation of methotrexate owing to abnormal monitoring blood test result. Patients were followed-up from six months after their first prescription for methotrexate in primary care to the earliest of outcome, drug discontinuation for any other reason, leaving the practice, last data collection from the practice, death, five years, or 31 December 2019. Cox regression was performed to develop the risk equation, with bootstrapping used to shrink predictor effects for optimism. Multiple imputation handled missing predictor data. Model performance was assessed in terms of calibration and discrimination.

RESULTS

Data from 13 110 (854 events) and 23 999 (1486 events) participants were included in the development and validation cohorts, respectively. 11 candidate predictors (17 parameters) were included. In the development dataset, the optimism adjusted R² was 0.13 and the optimism adjusted Royston D statistic was 0.79. The calibration slope and Royston D statistic in the validation dataset for the entire follow-up period was 0.94 (95% confidence interval 0.85 to 1.02) and 0.75 (95% confidence interval 0.67 to 0.83), respectively. The prognostic model performed well in predicting outcomes in clinically relevant subgroups defined by age group, type of immune mediated inflammatory disease, and methotrexate dose.

CONCLUSION

A prognostic model was developed and validated that uses information collected during routine clinical care and may be used to risk stratify the frequency of monitoring blood test during long term methotrexate treatment.

A Systematic Review of Methods to Incorporate External Evidence into Trial-Based Survival Extrapolations for Health Technology Assessment

BACKGROUND

External evidence is commonly used to inform survival modeling for health technology assessment (HTA). While there are a range of methodological approaches that have been proposed, it is unclear which methods could be used and how they compare.

PURPOSE

This review aims to identify, describe, and categorize established methods to incorporate external evidence into survival extrapolation for HTA.

DATA SOURCES

Embase, MEDLINE, EconLit, and Web of Science databases were searched to identify published methodological studies, supplemented by hand searching and citation tracking.

STUDY SELECTION

Eligible studies were required to present a novel extrapolation approach incorporating external evidence (i.e., data or information) within survival model estimation.

DATA EXTRACTION

Studies were classified according to how the external evidence was integrated as a part of model fitting. Information was extracted concerning the model-fitting process, key requirements, assumptions, software, application contexts, and presentation of comparisons with, or validation against, other methods.

DATA SYNTHESIS

Across 18 methods identified from 22 studies, themes included use of informative prior(s) (n = 5), piecewise (n = 7), and general population adjustment (n = 9), plus a variety of "other" (n = 8) approaches. Most methods were applied in cancer populations (n = 13). No studies compared or validated their method against another method that also incorporated external evidence.

LIMITATIONS

As only studies with a specific methodological objective were included, methods proposed as part of another study type (e.g., an economic evaluation) were excluded from this review.

CONCLUSIONS

Several methods were identified in this review, with common themes based on typical data sources and analytical approaches. Of note, no evidence was found comparing the identified methods to one another, and so an assessment of different methods would be a useful area for further research.HighlightsThis review aims to identify methods that have been used to incorporate external evidence into survival extrapolations, focusing on those that may be used to inform health technology assessment.We found a range of different approaches, including piecewise methods, Bayesian methods using informative priors, and general population adjustment methods, as well as a variety of "other" approaches.No studies attempted to compare the performance of alternative methods for incorporating external evidence with respect to the accuracy of survival predictions. Further research investigating this would be valuable.

The Cost-Effectiveness of Belimumab and Voclosporin for Patients with Lupus Nephritis in the United States

BACKGROUND AND OBJECTIVES

Despite existing therapies, people with lupus nephritis progress to kidney failure and have reduced life expectancy. Belimumab and voclosporin are two new disease-modifying therapies recently approved for the treatment of lupus nephritis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A de novo economic model was developed to estimate the cost-effectiveness of these therapies, including the following health states: "complete response," "partial response," and "active disease" defined by eGFR and proteinuria changes, kidney failure, and death. Short-term data and mean cohort characteristics were sourced from pivotal clinical trials of belimumab (the Belimumab International Study in Lupus Nephritis) and voclosporin (the Aurinia Urinary Protection Reduction Active-Lupus with Voclosporin trial and Aurinia Renal Response in Active Lupus With Voclosporin). Risk of mortality and kidney failure were on the basis of survival modeling using published Kaplan-Meier data. Each drug was compared with the standard of care as represented by the comparator arm in its respective pivotal trial(s) using US health care sector perspective, with a societal perspective also explored.

RESULTS

In the health care perspective probabilistic analysis, the incremental cost-effectiveness ratio for belimumab compared with its control arm was estimated to be approximately $95,000 per quality-adjusted life year. The corresponding incremental ratio for voclosporin compared with its control arm was approximately $150,000 per quality-adjusted life year. Compared with their respective standard care arms, the probabilities of belimumab and voclosporin being cost effective at a threshold of $150,000 per quality-adjusted life year were 69% and 49%, respectively. Cost-effectiveness was dependent on assumptions made regarding survival in response states, costs and utilities in active disease, and the utilities in response states. In the analysis from a societal perspective, the incremental ratio for belimumab was estimated to be approximately $66,000 per quality-adjusted life year, and the incremental ratio for voclosporin was estimated to be approximately $133,000 per quality-adjusted life year.

CONCLUSIONS

Compared with their respective standard care arms, belimumab but not voclosporin met willingness-to-pay thresholds of $100,000 per quality-adjusted life year. Despite potential clinical superiority in the informing trials, there remains high uncertainty around the cost-effectiveness of voclosporin.

Non-invasive diagnosis of deep vein thrombosis from ultrasound imaging with machine learning

Deep vein thrombosis (DVT) is a blood clot most commonly found in the leg, which can lead to fatal pulmonary embolism (PE). Compression ultrasound of the legs is the diagnostic gold standard, leading to a definitive diagnosis. However, many patients with possible symptoms are not found to have a DVT, resulting in long referral waiting times for patients and a large clinical burden for specialists. Thus, diagnosis at the point of care by non-specialists is desired. We collect images in a pre-clinical study and investigate a deep learning approach for the automatic interpretation of compression ultrasound images. Our method provides guidance for free-hand ultrasound and aids non-specialists in detecting DVT. We train a deep learning algorithm on ultrasound videos from 255 volunteers and evaluate on a sample size of 53 prospectively enrolled patients from an NHS DVT diagnostic clinic and 30 prospectively enrolled patients from a German DVT clinic. Algorithmic DVT diagnosis performance results in a sensitivity within a 95% CI range of (0.82, 0.94), specificity of (0.70, 0.82), a positive predictive value of (0.65, 0.89), and a negative predictive value of (0.99, 1.00) when compared to the clinical gold standard. To assess the potential benefits of this technology in healthcare we evaluate the entire clinical DVT decision algorithm and provide cost analysis when integrating our approach into diagnostic pathways for DVT. Our approach is estimated to generate a positive net monetary benefit at costs up to £72 to £175 per software-supported examination, assuming a willingness to pay of £20,000/QALY.

Probabilistic Sensitivity Analysis in Cost-Effectiveness Models: Determining Model Convergence in Cohort Models

Probabilistic sensitivity analysis (PSA) demonstrates the parameter uncertainty in a decision problem. The technique involves sampling parameters from their respective distributions (rather than simply using mean/median parameter values). Guidance in the literature, and from health technology assessment bodies, on the number of simulations that should be performed suggests a 'sufficient number', or until 'convergence', which is seldom defined. The objective of this tutorial is to describe possible outcomes from PSA, discuss appropriate levels of accuracy, and present guidance by which an analyst can determine if a sufficient number of simulations have been conducted, such that results are considered to have converged. The proposed approach considers the variance of the outcomes of interest in cost-effectiveness analysis as a function of the number of simulations. A worked example of the technique is presented using results from a published model, with recommendations made on best practice. While the technique presented remains essentially arbitrary, it does give a mechanism for assessing the level of simulation error, and thus represents an advance over current practice of a round number of simulations with no assessment of model convergence.

Conceptual model for the health technology assessment of current and novel interventions in rheumatoid arthritis

The objective of this study was to evaluate current approaches to economic modeling in rheumatoid arthritis (RA) and propose a new conceptual model for evaluation of the cost-effectiveness of RA interventions. We followed recommendations from the International Society of Pharmacoeconomics and Outcomes Research-Society of Medical Decision Making (ISPOR-SMDM) Modeling Good Research Practices Task Force-2. The process involved scoping the decision problem by a working group and drafting a preliminary cost-effectiveness model framework. A systematic literature review (SLR) of existing decision-analytic models was performed and analysis of an RA registry was conducted to inform the structure of the draft conceptual model. Finally, an expert panel was convened to seek input on the draft conceptual model. The proposed conceptual model consists of three separate modules: 1) patient characteristic module, 2) treatment module, and 3) outcome module. Consistent with the scope, the conceptual model proposed six changes to current economic models in RA. These changes proposed are to: 1) use composite measures of disease activity to evaluate treatment response as well as disease progression (at least two measures should be considered, one as the base case and one as a sensitivity analysis); 2) conduct utility mapping based on disease activity measures; 3) incorporate subgroups based on guideline-recommended prognostic factors; 4) integrate realistic treatment patterns based on clinical practice/registry datasets; 5) assimilate outcomes that are not joint related (extra-articular outcomes); and 6) assess mortality based on disease activity. We proposed a conceptual model that incorporates the current understanding of clinical and real-world evidence in RA, as well as of existing modeling assumptions. The proposed model framework was reviewed with experts and could serve as a foundation for developing future cost-effectiveness models in RA.

Associations of objective physical activity with insulin sensitivity and circulating adipokine profile: the Framingham Heart Study

The purpose of this study was to explore the relation of physical activity (PA) and sedentary time (SED) to insulin sensitivity and adipokines. We assessed PA and SED using Actical accelerometers and insulin resistance (HOMA-IR) in 2109 participants (free of type 1 and 2 diabetes mellitus) from Framingham Generation 3 and Omni 2 cohorts (mean age 46 years, 54% women). Systemic inflammation (C-reactive protein [CRP]) and circulating adipokines were measured 6 years earlier. Steps per day, moderate-to-vigorous PA (MVPA) and SED per wear time (%SED) were predictor variables in multivariable regression analyses, with HOMA-IR, CRP and circulating adipokines as outcome measures. We reported that higher MVPA and more steps per day were associated with lower HOMA-IR, adjusting for %SED (β = -0.036, P = 0.002; β = -0.041, P = 0.005). Steps were inversely associated with CRP, but were directly associated with insulin-like growth factor (IGF)-1 levels (β = -0.111, P = 0.002; β = 3.293, P = 0.007). %SED was positively associated with HOMA-IR (β = 0.033, P < 0.0001), but non-significant after adjusting for MVPA (P = 0.13). %SED was associated with higher ratio of leptin/leptin receptor (sOB-R) and higher adipocyte fatty acid-binding protein (FABP)4 (β = 0.096, P < 0.0001; β = 0.593, P = 0.002). Our findings suggest differential influences of PA vs. SED on metabolic pathways, with PA modulating insulin resistance and inflammation, whereas SED influences FABPs.

Gaussian Process Modeling in Conjunction with Individual Patient Simulation Modeling: A Case Study Describing the Calculation of Cost-Effectiveness Ratios for the Treatment of Established Osteoporosis

Individual patient-level models can simulate more complex disease processes than cohort-based approaches. However, large numbers of patients need to be simulated to reduce 1storder uncertainty, increasing the computational time required and often resulting in the inability to perform extensive sensitivity analyses. A solution, employing Gaussian process techniques, is presented using a case study, evaluating the cost-effectiveness of a sample of treatments for established osteoporosis. The Gaussian process model accurately formulated a statistical relationship between the inputs to the individual patient model and its outputs. This model reducedthe time required for future runs from 150 min to virtually-instantaneous, allowing probabilistic sensitivity analyses-to be undertaken. This reduction in computational time was achieved with minimal loss in accuracy. The authors believe that this case study demonstrates the value of this technique in handling 1st- and 2nd-order uncertainty in the context of health economic modeling, particularly when more widely used techniques are computationally expensive or are unable to accurately model patient histories.

Enhancements to angioplasty for peripheral arterial occlusive disease: systematic review, cost-effectiveness assessment and expected value of information analysis

BACKGROUND

There have been rapid technological developments aimed at improving short- and long-term results of percutaneous transluminal balloon angioplasty (PTA) in peripheral arterial occlusive disease (PAD).

OBJECTIVES

To assess current clinical effectiveness and cost-effectiveness evidence of additional techniques to standard PTA for PAD, develop a health economic model to assess cost-effectiveness and to identify where further research is needed.

DATA SOURCES

Relevant electronic databases, including MEDLINE, EMBASE and The Cochrane Library were searched from inception to 2011, between May and October 2011.

METHODS

Systematic reviews were conducted of clinical effectiveness and cost-effectiveness. The population was participants with symptomatic PAD undergoing endovascular treatment for disease distal to the inguinal ligament. Interventions were modifications of and adjuncts to PTA in the peripheral circulation, compared with conventional PTA. Outcomes included measures of clinical effectiveness and costs. Data were extracted from randomised controlled trials (RCTs), which were quality assessed using standard criteria. Where appropriate, meta-analyses using fixed- and random-effects methods produced relative risks (RRs). A discrete-event simulation model was developed to assess the relative cost-effectiveness of the interventions from a NHS perspective over a lifetime. The patient populations of intermittent claudication (IC) and critical limb ischaemia (CLI) were modelled separately. Univariate and probabilistic sensitivity analyses were undertaken.

RESULTS

In total, 40 RCTs were included, many of which had small sample sizes. Significantly reduced restenosis rates were shown in meta-analyses of self-expanding stents (SES) {RR 0.67 [95% confidence interval (CI) 0.52 to 0.87]}, endovascular brachytherapy (EVBT) [RR 0.63 (95% CI 0.48 to 0.83)] at 12 months and drug-coated balloons (DCBs) at 6 months [RR 0.40 (95% CI 0.23 to 0.69)], and single studies of stent-graft or drug-eluting stent (DES), compared with PTA; a single study showed improvements with DES versus bare-metal stents (BMSs). Compared with PTA, walking capacity was not significantly affected by cutting balloon, balloon-expandable stents or EVBT; in SES, there was evidence of improvement in walking capacity after up to 12 months. The use of DCBs dominated both the assumed standard practice of PTA with bailout BMS and all other interventions because it lowered lifetime costs and improved quality of life (QoL). These results were seen for both patient populations (IC and CLI). Sensitivity analyses showed that the results were robust to different assumptions about the clinical benefits attributable to the interventions, suggesting that the use of DCBs is cost-saving.

LIMITATIONS

Differing definitions of restenosis made direct comparison across trials difficult. There were few data available for walking capacity and QoL.

CONCLUSIONS

The evidence showed a significant benefit to reducing restenosis rates for self-expanding and DESs, stent-graft, EVBT and DCBs. If it is assumed that patency translates into beneficial long-term clinical outcomes, then DCB and bail-out DES are most likely to be the cost-effective enhancements to PTA. A RCT comparing current recommended practice (PTA with bail-out BMS) with DCB and bail-out DES could assess long-term follow-up and cost-effectiveness. Data relating patency status to the need for reintervention and to the probability of symptoms returning should be collected, as should health-related QoL measures [European Quality of Life-5 Dimensions (EQ-5D) and maximum walking distance].

STUDY REGISTRATION

This study is registered as PROSPERO CRD42012002014.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Predictors of unattempted central venous catheterization in septic patients eligible for early goal-directed therapy

INTRODUCTION

Central venous catheterization (CVC) can be an important component of the management of patients with severe sepsis and septic shock. CVC, however, is a time- and resource-intensive procedure associated with serious complications. The effects of the absence of shock or the presence of relative contraindications on undertaking central line placement in septic emergency department (ED) patients eligible for early goal-directed therapy (EGDT) have not been well described. We sought to determine the association of relative normotension (sustained systolic blood pressure >90 mmHg independent of or in response to an initial crystalloid resuscitation of 20 mL/kg), obesity (body mass index [BMI] ≥30), moderate thrombocytopenia (platelet count <50,000 per μL), and coagulopathy (international normalized ratio ≥2.0) with unattempted CVC in EGDT-eligible patients.

METHODS

This was a retrospective cohort study of 421 adults who met EGDT criteria in 5 community EDs over a period of 13 months. We compared patients with attempted thoracic (internal jugular or subclavian) CVC with those who did not undergo an attempted thoracic line. We also compared patients with any attempted CVC (either thoracic or femoral) with those who did not undergo any attempted central line. We used multivariate logistic regression analysis to calculate adjusted odd ratios (AORs).

RESULTS

In our study, 364 (86.5%) patients underwent attempted thoracic CVC and 57 (13.5%) did not. Relative normotension was significantly associated with unattempted thoracic CVC (AOR 2.6 95% confidence interval [CI], 1.6-4.3), as were moderate thrombocytopenia (AOR 3.9; 95% CI, 1.5-10.1) and coagulopathy (AOR 2.7; 95% CI, 1.3-5.6). When assessing for attempted catheterization of any central venous site (thoracic or femoral), 382 (90.7%) patients underwent attempted catheterization and 39 (9.3%) patients did not. Relative normotension (AOR 2.3; 95% CI, 1.2-4.5) and moderate thrombocytopenia (AOR 3.9; 95% CI, 1.5-10.3) were significantly associated with unattempted CVC, whereas coagulopathy was not (AOR 0.6; 95% CI, 0.2-1.8). Obesity was not significantly associated with unattempted CVC, either thoracic in location or at any site.

CONCLUSION

Septic patients eligible for EGDT with relative normotension and those with moderate thrombocytopenia were less likely to undergo attempted CVC at any site. Those with coagulopathy were also less likely to undergo attempted thoracic central line placement. Knowledge of the decision-making calculus at play for physicians considering central venous catheterization in this population can help inform physician education and performance improvement programs.

The cost-effectiveness of diagnostic management strategies for children with minor head injury

AIM

To estimate the cost-effectiveness of diagnostic management strategies for children with minor head injury and identify an optimal strategy.

METHODS

A probabilistic decision analysis model was developed to estimate the costs and quality-adjusted life years (QALYs) accrued by each of six potential management strategies for minor head injury, including a theoretical 'zero option' strategy of discharging all patients home without investigation. The model took a lifetime horizon and the perspective of the National Health Service.

RESULTS

The optimal strategy was based on the Children's Head injury Algorithm for the prediction of Important Clinical Events (CHALICE) rule, although the costs and outcomes associated with each strategy were broadly similar.

CONCLUSIONS

Liberal use of CT scanning based on a high sensitivity decision rule is not only effective but also cost saving, with the CHALICE rule being the optimal strategy, although there is some uncertainty in the results. Incremental changes in the costs and QALYs are very small when all selective CT strategies are compared. The estimated cost of caring for patients with brain injury worsened by delayed treatment is very high compared with the cost of CT scanning. This analysis suggests that all hospitals receiving children with minor head injury should have unrestricted access to CT scanning for use in conjunction with evidence-based guidelines.

A self-assembling peptide matrix used to control stiffness and binding site density supports the formation of microvascular networks in three dimensions

A three-dimensional (3-D) cell culture system that allows control of both substrate stiffness and integrin binding density was created and characterized. This system consisted of two self-assembling peptide (SAP) sequences that were mixed in different ratios to achieve the desired gel stiffness and adhesiveness. The specific peptides used were KFE ((acetyl)-FKFEFKFE-CONH2), which has previously been reported not to support cell adhesion or MVN formation, and KFE-RGD ((acetyl)-GRGDSP-GG-FKFEFKFE-CONH2), which is a similar sequence that incorporates the RGD integrin binding site. Storage modulus for these gels ranged from ∼60 to 6000Pa, depending on their composition and concentration. Atomic force microscopy revealed ECM-like fiber microarchitecture of gels consisting of both pure KFE and pure KFE-RGD as well as mixtures of the two peptides. This system was used to study the contributions of both matrix stiffness and adhesiveness on microvascular network (MVN) formation of endothelial cells and the morphology of human mesenchymal stem cells (hMSC). When endothelial cells were encapsulated within 3-D gel matrices without binding sites, little cell elongation and no network formation occurred, regardless of the stiffness. In contrast, matrices containing the RGD binding site facilitated robust MVN formation, and the extent of this MVN formation was inversely proportional to matrix stiffness. Compared with a matrix of the same stiffness with no binding sites, a matrix containing RGD-functionalized peptides resulted in a ∼2.5-fold increase in the average length of network structure, which was used as a quantitative measure of MVN formation. Matrices with hMSC facilitated an increased number and length of cellular projections at higher stiffness when RGD was present, but induced a round morphology at every stiffness when RGD was absent. Taken together, these results demonstrate the ability to control both substrate stiffness and binding site density within 3-D cell-populated gels and reveal an important role for both stiffness and adhesion on cellular behavior that is cell-type specific.

Cost-effectiveness analysis of enhancements to angioplasty for infrainguinal arterial disease

Background

The aim was to perform an economic evaluation of the cost-effectiveness of endovascular enhancements to percutaneous transluminal balloon angioplasty (PTA) with bail-out bare metal stents for infrainguinal peripheral arterial disease.

Methods

The following interventions were considered: PTA with no bail-out stenting, PTA with bail-out drug-eluting stents, drug-coated balloons, primary bare metal stents, primary drug-eluting stents, endovascular brachytherapy, stent-grafts and cryoplasty. A discrete-event simulation model was developed to assess the relative cost-effectiveness of the interventions from a health service perspective over a lifetime. Populations of patients with intermittent claudication (IC) and critical leg ischaemia (CLI) were modelled separately. Univariable and probabilistic sensitivity analyses were undertaken. Effectiveness was measured by quality-adjusted life-years (QALYs).

Results

For both patient populations, the use of drug-coated balloons dominated all other options by having both lower lifetime costs and greater effectiveness. For willingness-to-pay thresholds between £0 and £100 000 per additional QALY, the probability of drug-coated balloons being cost-effective was at least 58·3 per cent for patients with IC and at least 72·2 per cent for patients with CLI. Sensitivity analyses showed that the results were robust to different assumptions regarding the clinical benefits attributable to the interventions.

Conclusion

The use of drug-coated balloons represents a cost-effective alternative to the use of PTA with bail-out bare metal stents.

The cost-effectiveness of diagnostic management strategies for adults with minor head injury

STUDY OBJECTIVE

To estimate the cost-effectiveness of diagnostic management strategies for adults with minor head injury.

METHODS

A mathematical model was constructed to evaluate the incremental costs and effectiveness (Quality Adjusted Life years Gained, QALYs) of ten diagnostic management strategies for adults with minor head injuries. Secondary analyses were undertaken to determine the cost-effectiveness of hospital admission compared to discharge home and to explore the cost-effectiveness of strategies when no responsible adult was available to observe the patient after discharge.

RESULTS

The apparent optimal strategy was based on the high and medium risk Canadian CT Head Rule (CCHRhm), although the costs and outcomes associated with each strategy were broadly similar. Hospital admission for patients with non-neurosurgical injury on CT dominated discharge home, whilst hospital admission for clinically normal patients with a normal CT was not cost-effective compared to discharge home with or without a responsible adult at £39 and £2.5 million per QALY, respectively. A selective CT strategy with discharge home if the CT scan was normal remained optimal compared to not investigating or CT scanning all patients when there was no responsible adult available to observe them after discharge.

CONCLUSION

Our economic analysis confirms that the recent extension of access to CT scanning for minor head injury is appropriate. Liberal use of CT scanning based on a high sensitivity decision rule is not only effective but also cost-saving. The cost of CT scanning is very small compared to the estimated cost of caring for patients with brain injury worsened by delayed treatment. It is recommended therefore that all hospitals receiving patients with minor head injury should have unrestricted access to CT scanning for use in conjunction with evidence based guidelines. Provisionally the CCHRhm decision rule appears to be the best strategy although there is considerable uncertainty around the optimal decision rule. However, the CCHRhm rule appears to be the most widely validated and it therefore seems appropriate to conclude that the CCHRhm rule has the best evidence to support its use.

Diagnosis of DVT: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Objective testing for DVT is crucial because clinical assessment alone is unreliable and the consequences of misdiagnosis are serious. This guideline focuses on the identification of optimal strategies for the diagnosis of DVT in ambulatory adults.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that clinical assessment of pretest probability of DVT, rather than performing the same tests in all patients, should guide the diagnostic process for a first lower extremity DVT (Grade 2B). In patients with a low pretest probability of first lower extremity DVT, we recommend initial testing with D-dimer or ultrasound (US) of the proximal veins over no diagnostic testing (Grade 1B), venography (Grade 1B), or whole-leg US (Grade 2B). In patients with moderate pretest probability, we recommend initial testing with a highly sensitive D-dimer, proximal compression US, or whole-leg US rather than no testing (Grade 1B) or venography (Grade 1B). In patients with a high pretest probability, we recommend proximal compression or whole-leg US over no testing (Grade 1B) or venography (Grade 1B).

CONCLUSIONS

Favored strategies for diagnosis of first DVT combine use of pretest probability assessment, D-dimer, and US. There is lower-quality evidence available to guide diagnosis of recurrent DVT, upper extremity DVT, and DVT during pregnancy.

Trabectedin for the treatment of relapsed ovarian cancer

The paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of trabectedin for the treatment of relapsed platinum-sensitive ovarian cancer, based upon a review of the manufacturer's submission to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal process. The submission addressed only part of the decision problem and did not provide evidence to compare trabectedin (Yondelis®, PharmaMar) and pegylated liposomal doxorubicin hydrochloride (PLDH) (Caelyx®, Schering-Plough) with key comparators. The submission's direct comparison evidence came from one reasonable-quality randomised controlled trial (RCT) of trabectedin and PLDH versus PLDH alone (ET743-OVA-301). The results of the RCT were subdivided into the entire platinum-sensitive population (> 6-month relapse after initial platinum-based chemotherapy) and partially platinum-sensitive (≥ 6- to 12-month relapse) and fully platinum-sensitive (> 12-month relapse) populations. The outcomes included were overall survival, progression-free survival measured by three types of assessor, response rates, adverse effects of treatment, health-related quality of life and cost per quality-adjusted-life-year (QALY) gained. A mixed treatment comparison (MTC) meta-analysis comparing trabectedin and PLDH with single-agent PLDH within the entire platinum-sensitive population, with paclitaxel or with topotecan also formed part of the submission. The RCT data showed that trabectedin plus PLDH compared with PLDH monotherapy had a significant effect on overall survival only within the partially platinum-sensitive subgroup. PFS results reported by the independent radiologists showed significant effects in favour of the trabectedin and PLDH arm for the entire and partially platinum-sensitive populations only. Rates of grade 3 and 4 adverse events were mostly higher in the trabectedin and PLDH arm than in the PLDH alone arm. There were several issues regarding the undertaking of the MTC, and thus the data were not considered robust. Furthermore, the ERG did not believe the MTC to be necessary to answer the decision problem. The manufacturer submitted a de novo cost-effectiveness model. The main analysis compared trabectedin in combination with PLDH versus paclitaxel, topotecan and PLDH (each as monotherapy) in the entire platinum-sensitive population, using results estimated from the MTC. Additional analyses were presented comparing trabectedin in combination with PLDH versus PLDH monotherapy using direct evidence from the OVA-301 trial for the fully, partially and entire platinum-sensitive populations. The cost per QALY gained for trabectedin in combination with PLDH versus PLDH monotherapy was estimated to be £ 70,076 in the main analysis. In the additional analyses, the cost per QALY gained for trabectedin in combination with PLDH versus PLDH monotherapy was £ 94,832, £ 43,996 and £ 31,092 for the entire, partially and fully platinum-sensitive populations, respectively. Additional work was undertaken by the ERG using patient-level data and amending some assumptions to provide a better statistical fit to the Kaplan-Meier data than the exponential distribution assumed by the manufacturer. The ERG base-case estimate of the cost per QALY of trabectedin in combination with PLDH ranged from £46,503 to £54,607 in the partially platinum-sensitive population. At the time of writing, trabectedin in combination with PLDH for the treatment of women with relapsed platinum-sensitive ovarian cancer is not recommended by NICE in the final appraisal determination.

Trabectedin for the treatment of relapsed ovarian cancer

The paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of trabectedin for the treatment of relapsed platinum-sensitive ovarian cancer, based upon a review of the manufacturer’s submission to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal process. The submission addressed only part of the decision problem and did not provide evidence to compare trabectedin (Yondelis®, PharmaMar) and pegylated liposomal doxorubicin hydrochloride (PLDH) (Caelyx®, Schering-Plough) with key comparators. The submission’s direct comparison evidence came from one reasonable-quality randomised controlled trial (RCT) of trabectedin and PLDH versus PLDH alone (ET743-OVA-301). The results of the RCT were subdivided into the entire platinum-sensitive population (> 6-month relapse after initial platinum-based chemotherapy) and partially platinum-sensitive (≥ 6- to 12-month relapse) and fully platinum-sensitive (> 12-month relapse) populations. The outcomes included were overall survival, progression-free survival measured by three types of assessor, response rates, adverse effects of treatment, health-related quality of life and cost per quality-adjusted-life-year (QALY) gained. A mixed treatment comparison (MTC) meta-analysis comparing trabectedin and PLDH with single-agent PLDH within the entire platinum-sensitive population, with paclitaxel or with topotecan also formed part of the submission. The RCT data showed that trabectedin plus PLDH compared with PLDH monotherapy had a significant effect on overall survival only within the partially platinum-sensitive subgroup. PFS results reported by the independent radiologists showed significant effects in favour of the trabectedin and PLDH arm for the entire and partially platinum-sensitive populations only. Rates of grade 3 and 4 adverse events were mostly higher in the trabectedin and PLDH arm than in the PLDH alone arm. There were several issues regarding the undertaking of the MTC, and thus the data were not considered robust. Furthermore, the ERG did not believe the MTC to be necessary to answer the decision problem. The manufacturer submitted a de novo cost-effectiveness model. The main analysis compared trabectedin in combination with PLDH versus paclitaxel, topotecan and PLDH (each as monotherapy) in the entire platinum-sensitive population, using results estimated from the MTC. Additional analyses were presented comparing trabectedin in combination with PLDH versus PLDH monotherapy using direct evidence from the OVA-301 trial for the fully, partially and entire platinum-sensitive populations. The cost per QALY gained for trabectedin in combination with PLDH versus PLDH monotherapy was estimated to be £70,076 in the main analysis. In the additional analyses, the cost per QALY gained for trabectedin in combination with PLDH versus PLDH monotherapy was £94,832, £43,996 and £31,092 for the entire, partially and fully platinum-sensitive populations, respectively. Additional work was undertaken by the ERG using patient-level data and amending some assumptions to provide a better statistical fit to the Kaplan–Meier data than the exponential distribution assumed by the manufacturer. The ERG base-case estimate of the cost per QALY of trabectedin in combination with PLDH ranged from £46,503 to £54,607 in the partially platinum-sensitive population. At the time of writing, trabectedin in combination with PLDH for the treatment of women with relapsed platinum-sensitive ovarian cancer is not recommended by NICE in the final appraisal determination.

Trabectedin for the treatment of advanced metastatic soft tissue sarcoma

This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of trabectedin for the treatment of advanced metastatic soft tissue sarcoma, in accordance with the licensed indication, based on the evidence submission from the manufacturer to NICE as part of the single technology appraisal (STA) process. The outcomes stated in the manufacturer's definition of the decision problem were overall survival (OS), progression-free survival (PFS), response rates, adverse effects of treatment, health-related quality of life, and cost per quality-adjusted life-year (QALY) gained. The clinical evidence was derived from one randomised controlled trial (RCT), in which the licensed dose of trabectedin was compared with a different dose of trabectedin, and three phase II studies. In the RCT, the median OS was 13.9 months for the licensed dose of trabectedin, which was not significantly different from that for the comparator dose of trabectedin, which was 11.8 months. From the phase II uncontrolled trials, median OS was reported as 9.2 or 12.8 months. The RCT reported significantly superior PFS for the licensed dose of trabectedin (median 3.3 months) over the comparator trabectedin dose (median 2.3 months). One phase II uncontrolled trial reported median PFS as 1.9 months in the licensed dose of trabectedin. The RCT reported PFS rates at 6 months were 35.5% for the licensed dose of trabectedin, and 27.5% for the comparator dose of trabectedin. From the phase II uncontrolled trials, PFS rates at 6 months were 24.4% or 29%. For the RCT, deaths attributed to trabectedin occurred in 3.1% of the licensed dose, and 2.3% of the comparator group. The most common severe adverse events were neutropenia, although with a low rate of febrile neutropenia, thrombocytopenia, and aspartate aminotransferase and alanine aminotransferase elevation, although these were reported to be non-cumulative and reversible. Following dialogue iterations with the ERG team, the manufacturer revised the model twice. However, despite revisions, errors/inconsistencies were found in the latest version of the model and were corrected by the ERG (only for the base case). In the latest manufacturer's submission, the cost per QALY gained of trabectedin compared with best supportive care (BSC) was estimated to be 56,985 pounds for the base case using effectiveness from the STS (Soft Tissue Sarcomas)-201 trial for trabectedin and a pool analysis of the European Organisation for Research and Treatment of Cancer data set for BSC. This analysis was constrained to patients with L-sarcomas only. When the joint uncertainty between parameters was considered, the cost-effectiveness acceptability curve showed that trabectedin has a very low probability of being cost-effective at a threshold of 30,000 pounds per QALY gained compared with BSC for any scenario. The guidance has yet to be issued by NICE.

Intensity-modulated radiotherapy for the treatment of prostate cancer: a systematic review and economic evaluation

BACKGROUND

Prostate cancer (PC) is the most common cancer in men in the UK. Radiotherapy (RT) is a recognised treatment for PC and high-dose conformal radiotherapy (CRT) is the recommended standard of care for localised or locally advanced tumours. Intensity-modulated radiotherapy (IMRT) allows better dose distributions in RT.

OBJECTIVE

This report evaluates the clinical effectiveness and cost-effectiveness of IMRT for the radical treatment of PC.

DATA SOURCES

The following databases were searched: MEDLINE (1950-present), EMBASE (1980-present), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982-present), BIOSIS (1985-present), the Cochrane Database of Systematic Reviews (1991-present), the Cochrane Controlled Trials Register (1991-present), the Science Citation Index (1900-present) and the NHS Centre for Reviews and Dissemination databases (Database of Abstracts of Reviews of Effects, NHS Economic Evaluation Database, Health Technology Assessment) (1991-present). MEDLINE In-Process & Other Non-Indexed Citations was searched to identify any studies not yet indexed on MEDLINE. Current research was identified through searching the UK Clinical Research Network, National Research Register archive, the Current Controlled Trials register and the Medical Research Council Clinical Trials Register. In addition, abstracts of the American Society of Clinical Oncology, the American Society for Therapeutic Radiology and Oncology, and European Society for Therapeutic Radiology and Oncology conferences were browsed.

REVIEW METHODS

A systematic literature review of the clinical effectiveness and cost-effectiveness of IMRT in PC was conducted. Comparators were three-dimensional conformal radiotherapy (3DCRT) or radical prostatectomy. Outcomes sought were overall survival, biochemical [prostate-specific antigen (PSA)] relapse-free survival, toxicity and health-related quality of life (HRQoL). Fifteen electronic bibliographic databases were searched in January 2009 and updated in May 2009, and the reference lists of relevant articles were checked. Studies only published in languages other than English were excluded. An economic model was developed to examine the cost-effectiveness of IMRT in comparison to 3DCRT. Four scenarios were modelled based on the studies which reported both PSA survival and late gastrointestinal (GI) toxicity. In two scenarios equal PSA survival was assumed for IMRT and 3DCRT, the other two having greater PSA survival for the IMRT cohort. As there was very limited data on clinical outcomes, the model estimates progression to clinical failure and PC death from the surrogate outcome of PSA failure.

RESULTS

No randomised controlled trials (RCTs) of IMRT versus 3DCRT in PC were available, but 13 non-randomised studies comparing IMRT with 3DCRT were found, of which five were available only as abstracts. One abstract reported overall survival. Biochemical relapse-free survival was not affected by treatment group, except where there was a dose difference between groups, in which case higher dose IMRT was favoured over lower dose 3DCRT. Most studies reported an advantage for IMRT in GI toxicity, attributed to increased conformality of treatment compared with 3DCRT, particularly with regard to volume of rectum treated. There was some indication that genitourinary toxicity was worse for patients treated with dose escalated IMRT, although most studies did not find a significant treatment effect. HRQoL improved for both treatment groups following radiotherapy, with any group difference resolved by 6 months after treatment. No comparative studies of IMRT versus prostatectomy were identified. No comparative studies of IMRT in PC patients with bone metastasis were identified.

LIMITATIONS

The strength of the conclusions of this review are limited by the lack of RCTs, and any comparative studies for some patient groups.

CONCLUSIONS

The comparative data of IMRT versus 3DCRT seem to support the theory that higher doses, up to 81 Gy, can improve biochemical survival for patients with localised PC, concurring with data on CRT. The data also suggest that toxicity can be reduced by increasing conformality of treatment, particularly with regard to GI toxicity, which can be more easily achieved with IMRT than 3DCRT. Whether differences in GI toxicity between IMRT and 3DCRT are sufficient for IMRT to be cost-effective is uncertain, depending on the difference in incidence of GI toxicity, its duration and the cost difference between IMRT and 3DCRT.

Trabectedin for the treatment of advanced metastatic soft tissue sarcoma

This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of trabectedin for the treatment of advanced metastatic soft tissue sarcoma, in accordance with the licensed indication, based on the evidence submission from the manufacturer to NICE as part of the single technology appraisal (STA) process. The outcomes stated in the manufacturer’s definition of the decision problem were overall survival (OS), progression-free survival (PFS), response rates, adverse effects of treatment, health-related quality of life, and cost per quality-adjusted life-year (QALY) gained. The clinical evidence was derived from one randomised controlled trial (RCT), in which the licensed dose of trabectedin was compared with a different dose of trabectedin, and three phase II studies. In the RCT, the median OS was 13.9 months for the licensed dose of trabectedin, which was not significantly different from that for the comparator dose of trabectedin, which was 11.8 months. From the phase II uncontrolled trials, median OS was reported as 9.2 or 12.8 months. The RCT reported significantly superior PFS for the licensed dose of trabectedin (median 3.3 months) over the comparator trabectedin dose (median 2.3 months). One phase II uncontrolled trial reported median PFS as 1.9 months in the licensed dose of trabectedin. The RCT reported PFS rates at 6 months were 35.5% for the licensed dose of trabectedin, and 27.5% for the comparator dose of trabectedin. From the phase II uncontrolled trials, PFS rates at 6 months were 24.4% or 29%. For the RCT, deaths attributed to trabectedin occurred in 3.1% of the licensed dose, and 2.3% of the comparator group. The most common severe adverse events were neutropenia, although with a low rate of febrile neutropenia, thrombocytopenia, and aspartate aminotransferase and alanine aminotransferase elevation, although these were reported to be non-cumulative and reversible. Following dialogue iterations with the ERG team, the manufacturer revised the model twice. However, despite revisions, errors/inconsistencies were found in the latest version of the model and were corrected by the ERG (only for the base case). In the latest manufacturer’s submission, the cost per QALY gained of trabectedin compared with best supportive care (BSC) was estimated to be £56,985 for the base case using effectiveness from the STS (Soft Tissue Sarcomas)-201 trial for trabectedin and a pool analysis of the European Organisation for Research and Treatment of Cancer data set for BSC. This analysis was constrained to patients with L–sarcomas only. When the joint uncertainty between parameters was considered, the cost-effectiveness acceptability curve showed that trabectedin has a very low probability of being cost-effective at a threshold of £30,000 per QALY gained compared with BSC for any scenario. The guidance has yet to be issued by NICE.

Thrombophilia testing in people with venous thromboembolism: systematic review and cost-effectiveness analysis

OBJECTIVES

To assess whether thrombophilia testing following a venous thrombotic event is clinically effective and cost-effective in the management of thrombosis compared with no testing for thrombophilia.

DATA SOURCES

Major electronic databases were searched from September to November 2006.

REVIEW METHODS

A systematic review of the clinical effectiveness and cost-effectiveness literature was undertaken according to standard methods. A discrete event simulation model was constructed to assess the cost-effectiveness of changing the standard 3-month duration of warfarin treatment to 10 years, 20 years or lifelong.

RESULTS

No clinical studies were identified that met the inclusion criteria for the systematic review. Further literature searches and clinical opinion were therefore used to inform the cost-effectiveness analysis. Thrombophilia testing in patients with pulmonary embolism (PE) had an estimated mean cost per quality-adjusted life-year (QALY) of below 20,000 pounds regardless of sex or age. In patients with a previous deep vein thrombosis (DVT), thrombophilia testing had an estimated mean cost per QALY of below 20,000 pounds in men aged 69 years or less and in women aged 49 years or less. The estimated duration of warfarin treatment (lifelong, 20 years, 10 years or no extended treatment) that was most cost-effective is presented for each age, sex, initial venous thromboembolism (VTE) event and type of thrombophilia.

CONCLUSIONS

In terms of determining the duration of anticoagulation management, scenarios were found in which the cost per QALY of thrombophilia testing was below 20,000 pounds. However, these results are subject to great uncertainty, largely because of lack of knowledge about the increased risk of recurrence with each type of thrombophilia. Results are influenced by the fact that men have a greater risk of recurrence than women and by the fact that the frequency of adverse events associated with warfarin treatment increases with age. Further research, for example on the likely sensitivity and specificity of the tests for specific types of thrombophilia, is needed to reduce the uncertainty associated with these results. Studies comparing patients with VTE tested for thrombophilia with those whose risk assessment was based on personal and family history of thrombosis would also be beneficial.

Triaging patients with serious head injury: results of a simulation evaluating strategies to bypass hospitals without neurosurgical facilities

OBJECTIVES

to inform the debate on whether seriously head-injured adult patients should be transported directly to the regional neurosurgical unit or indirectly after evaluation and stabilisation at the nearest hospital.

DESIGN

a simulation model was constructed to compare triage strategies and to identify those that predicted the maximum survivors. In each strategy, an estimate of the patient's condition in the field was used to determine the receiving hospital. The model used data from previous publications and local ambulance service and hospital databases. In the absence of valid data, expert clinical estimates were made and subjected to sensitivity analyses.

SETTING

an area in the North West Midlands of UK, covered by six acute hospitals including one with a regional neurosurgical unit.

OUTCOME MEASURE

the number of survivors predicted by each triage strategy.

RESULTS

five strategies were identified which consistently predicted the highest number of survivors. Compared with current policy it was predicted that in the North West Midlands, ten lives per year could be saved (6 per million total population per year). The results from sensitivity analyses did not alter these successful policies.

CONCLUSION

the successful strategies should be considered as potential improvements to be introduced into clinical practice.

Evaluation of the Low-Energy Value for the Adsorption Energy Distribution Function

This note presents an analytical method for calculating the minimal energy required to evaluate overall adsorption using Dubinin-Radushkevich theory. The method produces a result that is at least two orders of magnitude more accurate than that possible with numerical techniques.