Implantable cardioverter defibrillators: arrhythmias. A rapid and systematic review

PROPOSED SERVICE: The service proposed is the use of implantable cardioverter defibrillators (ICDs) in the management of risk factors leading to sudden cardiac death (SCD). ICDs are similar in size to a pacemaker and are intended to prevent death due to life-threatening ventricular tachyarrhythmias.

EPIDEMIOLOGY AND BACKGROUND

SCD occurs in approximately 100,000 people annually in the UK and is usually due to ventricular tachyarrhythmia. Increasing numbers of people are surviving a first episode of ventricular tachyarrhythmia and are at high risk of further episodes. Standard treatments for those at high risk have been anti-arrhythmic drugs, catheter ablation or surgery and, increasingly, vasodilating beta-blockers.

METHODS

Electronic databases were searched for the period 1980-99. In addition, bibliographies of related papers were assessed for relevant studies, and experts were contacted to identify additional published and unpublished references. Studies were included if they were systematic reviews, meta-analyses or randomised controlled trials (RCTs) comparing ICDs with conventional therapy in people at high risk of SCD.

NUMBER AND QUALITY OF STUDIES AND DIRECTION OF EVIDENCE

Seven RCTs on effectiveness the majority of which were of good quality, eight cost-effectiveness analyses most of which were older studies and based on non-UK data, and two good-quality literature reviews one of which was a critical appraisal of the literature of effectiveness and cost-effectiveness of ICD therapy, and the other a review of the cost-effectiveness of ICD therapy. These showed changes in absolute risk of total mortality ranging from an increase of 1.7% to a reduction of 22.8% (relative risk reductions of -7% to +54%).

SUMMARY OF BENEFITS

Estimated benefits from RCT data are 0.23-0.8 additional years of life with ICD therapy compared with anti-arrhythmic drug therapy.

COSTS

Unit cost of ICDs (based on 1999/2000 prices), ranges from pound 12,500 to pound 22,000. Total discounted costs for 3 years range from pound 20,000 to pound 29,000. COST-EFFECTIVENESS: Cost-effectiveness estimates in the literature identified range from $11,000 to $146,000 per life-year saved. Using UK cost data from three hospitals and trial survival data from one RCT, the estimate of cost-effectiveness from this review ranges between pound 20,250 and pound 87,000 per life-year saved. COST-UTILITY: Cost per quality-adjusted life-year is estimated by the authors of this review at pound 21,300 to pound 108,800 (using survival data from one trial and quality-of-life indices derived from clinical opinion). These figures remain speculative until quality-of-life data from ongoing trials are available to inform future UK cost-effectiveness/utility analyses.

IMPLICATIONS

If implemented for indications supported by evidence from RCTs, ICDs may cost the NHS in excess of pound 24 million per annum.

FUTURE RESEARCH

Future research should include the use of British Pacing and Electrophysiological Group registries to assess the use of different types of ICD and current service provision.

What are the relative merits of the sources used to identify potential research priorities for the NHS HTA programme?

The NHS Health Technology Assessment (HTA) Programme runs an annual process of identifying suggestions for health technology assessment. The objective of this paper is to describe and evaluate the relative importance of the different sources used by the program in 1998 to identify potential priorities. There were four different sources: a) a widespread consultation of healthcare commissioners, providers and consumers; b) research recommendations from systematic reviews; c) reconsidering previous research priorities which had not been taken forward for funding; and d) horizon scanning. Collectively, the four sources generated just over 1,100 HTA suggestions. By far the largest source of suggestions and priorities was the widespread consultation. However, the success rate of this source, in terms of being commissioned, was low. Research recommendations from systematic reviews provided the second largest source of priorities and the best success rate of all sources. Value was found from different sources for different healthcare areas.

Teaching critical appraisal skills in health care settings

BACKGROUND

Critical appraisal is the process of assessing and interpreting evidence by systematically considering its validity, results and relevance to an individual's work. Within the last decade critical appraisal has been added as a topic to many medical school and UK Royal College curricula, and several continuing professional development ventures have been funded to provide further training.

OBJECTIVES

To assess the effects of teaching critical appraisal skills to health professionals, on the process of care, patient outcomes and knowledge of health professionals.

SEARCH STRATEGY

We searched The Cochrane Library (to Issue 2 2000), MEDLINE (1966 to 1997), EMBASE (1980 to 1997), Eric (1966 to 1997), Cinahl (1982 to 1997), Lisa (1976 to 1997), Sigle (1980 to 1997), Science Citation Index (1981 to 1997), PsycLit (1974 to 1997), the world-wide-web, and reference lists of articles. We also contacted major medical education centres.

SELECTION CRITERIA

Randomised trials, controlled clinical trials, controlled before and after studies and interrupted time series analyses of educational interventions teaching critical appraisal to health professionals. The outcomes were: process of care; patient mortality, quality of life, and satisfaction; and health professional knowledge/awareness based upon objective, standardised, validated instruments.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and three reviewers independently assessed study quality.

MAIN RESULTS

One USA hospital-based randomised trial was included involving 44 doctors. The outcome assessed was critical appraisal knowledge. Process of care, patient health or attitude/awareness outcomes were not assessed. Critical appraisal teaching was reported to have resulted in a 25% improvement (adjusted figure) in critical appraisal knowledge in the intervention group compared to a 6% improvement in the control group, which was statistically significant (p=0.02).

REVIEWER'S CONCLUSIONS

There is evidence that critical appraisal teaching has positive effects on participants' knowledge, but as only one study met the inclusion criteria the validity of drawing general conclusions about the effects of teaching critical appraisal is debatable. There are large gaps in the evidence as to whether teaching critical appraisal impacts on decision-making or patient outcomes. It is also unclear whether the size of benefit seen is large enough to be of practical significance, or whether this varies according to participant background or teaching method. The evidence supporting all outcomes is weakened by the generally poorly designed, executed and reported studies that we found.

Apolipoprotein D

Apolipoprotein D (apoD) is a 29-kDa glycoprotein that is primarily associated with high density lipoproteins in human plasma. It is an atypical apolipoprotein and, based on its primary structure, apoD is predicted to be a member of the lipocalin family. Lipocalins adopt a beta-barrel tertiary structure and transport small hydrophobic ligands. Although apoD can bind cholesterol, progesterone, pregnenolone, bilirubin and arachidonic acid, it is unclear if any, or all of these, represent its physiological ligands. The apoD gene is expressed in many tissues, with high levels of expression in spleen, testes and brain. ApoD is present at high concentrations in the cyst fluid of women with gross cystic disease of the breast, a condition associated with increased risk of breast cancer. It also accumulates at sites of regenerating peripheral nerves and in the cerebrospinal fluid of patients with neurodegenerative conditions, such as Alzheimer's disease. ApoD may, therefore, participate in maintenance and repair within the central and peripheral nervous systems. While its role in metabolism has yet to be defined, apoD is likely to be a multi-ligand, multi-functional transporter. It could transport a ligand from one cell to another within an organ, scavenge a ligand within an organ for transport to the blood or could transport a ligand from the circulation to specific cells within a tissue.

Orlistat for the treatment of obesity: rapid review and cost-effectiveness model

The aim of this study is to clarify the potential benefits, disbenefits and costs of Orlistat for the treatment of obesity. The method was a search for relevant systematic reviews and randomized controlled trials, in Medline, Pre-Medline, Embase and the Cochrane Library, using Orlistat and its synonyms. Identified trials were appraised using a standard appraisal checklist and trial data were extracted for use in cost-effectiveness modelling. Three large multicentre, randomized placebo controlled trials were included in the rapid review. On average, Orlistat results in obese people losing an additional 3-4% of their initial body weight over diet alone during a 2 year period. There was no strong evidence that this short-term weight loss would have a longer-term impact on morbidity and mortality. The cost utility of Orlistat treatment was estimated at around 46,000 Pounds per Quality Adjusted Life Year gained (extreme values sensitivity analysis 14,000 Pounds to 132,000 Pounds). This rapid review raises some important questions about the potential value of Orlistat in the treatment of obesity. Further research is needed, not only to clarify the longer-term impact of Orlistat treatment, but also to uncover the longer-term impact on mortality and morbidity from short-term weight loss.

Positron emission tomography: establishing priorities for health technology assessment

BACKGROUND

Positron emission tomography (PET) is an expensive diagnostic imaging technology. Despite the long history of PET development, the costs and effectiveness of its use in routine clinical practice remain unknown. Against this background of uncertainty regarding the clinical role of PET, the UK Standing Group on Health Technology requested a review of its current and potential role which would enable research priorities in this area to be established.

OBJECTIVES

This 3-month project had two explicit objectives: (1) to review the state of knowledge regarding the clinical applications of PET; (2) to determine the key health technology assessment (HTA) research questions relating to the use of PET in the UK.

METHODS

A literature review to ascertain the state of knowledge regarding the clinical applications of PET and a three-round Delphi study to inform the key HTA research questions relating to the use of PET in the UK were undertaken. The results of an earlier systematic review, published by the Veteran's Health Administration (VHA) in the USA in 1996, were used as the starting point for the literature review. The VHA review was updated and extended by means of MEDLINE and Cochrane Library database searches. Participants in the Delphi study were selected by discussion with five individuals in the UK with an interest in, and awareness of, developments in PET. As a result of their suggestions, 43 individuals were initially invited to participate, of whom two did not feel appropriately qualified. Questionnaires were sent by facsimile to all invited participants, who were asked to return the completed forms by facsimile within a week. The content and structure of the Delphi study was informed by the results of the literature review. The responses and comments of the participants were a major source of information for this report.

RESULTS

Clinical applications for PET have been advocated in three broad disease groups: oncology, cardiology and neuropsychiatric disorders. There are currently four PET modalities that need to be considered when assessing its potential clinical role in the UK: full ring PET scanners operating in two or three dimensions (available at five sites); partial ring rotating PET scanners (one currently operating in the UK); coincidence imaging with modified gamma camera technology; and high-energy collimator imaging of 511 keV photons with modified gamma camera technology. There is a paucity of available evidence relating to the cost-effectiveness of the various PET modalities in all of the clinical indications for which the technology is currently being advocated. In addition, many existing reports on the diagnostic accuracy of PET are limited because they are liable to bias and often relate only to very small patient numbers. The results of the Delphi study indicated that the four most important research priorities for the NHS, in descending order of their importance, are: (1) the relative cost-effectiveness of (a) full ring PET, (b) gamma camera PET using coincidence imaging and (c) existing diagnostic strategies to determine staging prior to operative intervention for lung cancer; (2) partial ring PET compared with full ring PET in oncology (3) the relative cost-effectiveness of (a) full ring PET, (b) gamma camera PET using coincidence imaging and (c) existing diagnostic strategies to stage and monitor treatment response in breast cancer; (4) the relative cost-effectiveness of (a) gamma camera PET using coincidence imaging and (b) 511 keV collimated positron imaging for assessing myocardial viability when selecting patients for revascularisation surgery. Vignettes describing each of the research priorities are provided in the main report.

CONCLUSIONS

The findings of this project, which was undertaken rapidly in order to inform HTA research prioritization in the UK, provide a contemporary overview of the potential clinical role for PET in the NHS. Evidence is needed that using PET as a diagnostic

Leflunomide and rheumatoid arthritis: a systematic review of effectiveness, safety and cost implications

OBJECTIVE

To assess the effectiveness, safety and cost implications of leflunomide treatment for rheumatoid arthritis.

DESIGN

Systematic review.

SETTING

Four trials retrieved from Medline, Embase, the Cochrane Library, Econlit, HMIC (Dhdata), HMIC (Helmis), HMIC (King's Fund Database) and Best Evidence3.

MAIN OUTCOME MEASURES

Efficacy measures (including tender joint counts, swollen joint counts, assessment of functioning, Health Assessment Questionnaire, Modified Health Assessment Questionnaire, pain (visual analogue scale), Erythrocyte Sedimentation Rate, C-reactive Protein), radiological progression and treatment adverse events.

RESULTS

Leflunomide therapy was demonstrated to be significantly superior to placebo in relation to the efficacy outcome measures and it slowed the radiological progression of patients' disease in three studies. Treatment success and duration of sustained response were also significantly superior than on placebo, as were quality of life measures. Leflunomide treatment was comparable to sulphasalazine and methotrexate with respect to efficacy, radiological progression and quality of life measures. The most common adverse effects leading to withdrawal from leflunomide treatment were gastrointestinal symptoms (diarrhoea and nausea), allergic reactions (rash and pruritus), alopecia, dyspepsia, hypertension and elevated transaminase levels. Weight loss and dizziness have also been reported for leflunomide therapy. Leflunomide is more expensive than most DMARDs, costing about pound400 a year more than sulphasalazine.

CONCLUSION

Despite the small number of published articles relating to leflunomide treatment, the evidence suggests that leflunomide is similar in efficacy to both sulphasalazine and methotrexate, although with a differential pattern of side-effects. There is a need for further research to assess the long-term outcomes of leflunomide treatment.

Eye movement desensitization and reprocessing in the treatment of post-traumatic stress disorder: a review of an emerging therapy

BACKGROUND

Eye Movement Desensitization and Reprocessing (EMDR) is a relatively new form of psychotherapy for post-traumatic stress disorder. We critically reviewed randomized controlled trials of EMDR.

METHODS

A wide range of electronic databases and reference lists of articles obtained were searched and relevant experts were consulted. Studies were critically appraised according to established criteria.

RESULTS

We found 16 published randomized controlled trials (RCTs) comparing EMDR with alternative psychotherapy treatments, variants of EMDR and with delayed treatment groups. Studies were generally small (mean number of patients = 35) and of variable methodological quality, with only five reporting blinding of outcome assessors to treatment allocation, and in some cases with high loss to follow-up. In most cases EMDR was shown to be effective at reducing symptoms up to 3 months after treatment. In one case benefit was maintained up to 9 months and in another (uncontrolled) follow-up treatment effect was present at 15 months. Two studies suggest that EMDR is as effective as exposure therapies, three claim greater effectiveness in comparison to relaxation training, and three claim superiority over delayed treatment groups. Of the studies examining specific treatment components, two found that treatment with eyes moving was more effective than eyes fixed, while three studies found the two procedures to be of equal effectiveness.

CONCLUSION

The evidence in support of EMDR is of limited quality but results are encouraging for this inexpensive, simple therapy. Further research is warranted in larger samples with longer periods of follow-up.

Binding of an antibody mimetic of the human low density lipoprotein receptor to apolipoprotein E is governed through electrostatic forces. Studies using site-directed mutagenesis and molecular modeling

Monoclonal antibody 2E8 is specific for an epitope that coincides with the binding site of the low density lipoprotein receptor (LDLR) on human apoE. Its reactivity with apoE variants resembles that of the LDLR: it binds well with apoE3 and poorly with apoE2. The heavy chain complementarity-determining region (CDRH) 2 of 2E8 shows homology to the ligand-binding domain of the LDLR. To define better the structural basis of the 2E8/apoE interaction and particularly the role of electrostatic interactions, we generated and characterized a panel of 2E8 variants. Replacement of acidic residues in the 2E8 CDRHs showed that Asp(52), Glu(53), and Asp(56) are essential for high-affinity binding. Although Asp(31) (CDRH1), Glu(58) (CDRH2), and Asp(97) (CDRH3) did not appear to be critical, the Asp(97) --> Ala variant acquired reactivity with apoE2. A Thr(57) --> Glu substitution increased affinity for both apoE3 and apoE2. The affinities of wild-type 2E8 and variants for apoE varied inversely with ionic strength, suggesting that electrostatic forces contribute to both antigen binding and isoform specificity. We propose a model of the 2E8.apoE immune complex that is based on the 2E8 and apoE crystal structures and that is consistent with the apoE-binding properties of wild-type 2E8 and its variants. Given the similarity between the LDLR and 2E8 in terms of specificity, the LDLR/ligand interaction may also have an important electrostatic component.

Immunological analysis of the tegument phosphoprotein ppUL83 of human cytomegalovirus

Immunological properties of the tegument phosphoprotein, ppUL83, of human cytomegalovirus (HCMV), expressed using a replication deficient recombinant adenovirus vector (RAd83) are described. The initial characterisation of this protein was carried out by immunofluorescence (IF), immunoprecipitation (RIP) and immunoblotting using nine mouse monoclonal antibodies (Mabs) directed against five linear and four conformational epitopes of ppUL83. The reactivity of the recombinant protein with the Mabs was similar to that observed with native ppUL83, although, the kinetics of its expression was in agreement with expression derived from the HCMV major immediate early promoter (MIEP). The recombinant antigen was used successfully in an Enzyme Immunoassay (EIA) for the detection of IgG class antibodies in 171 sequential sera taken from 21 heart transplant recipients. Comparison of HCMV-infected and RAd83-infected cell extracts in this experiment showed that recombinant antigen could substitute whole virus extracts as a single well-characterised protein in EIA. Serum IgG avidity measurements, using the recombinant ppUL83, differentiated between primary and past HCMV infections in the population studied.

rhDNase therapy for the treatment of cystic fibrosis patients with mild to moderate lung disease

OBJECTIVE

To assess the cost-effectiveness of rhDNase (Pulmozyme(R)) for patients with cystic fibrosis (CF) aged 5 years or more, with mild to moderate lung disease. The review addresses four questions: a) does rhDNase therapy work in the short term?, b) does rhDNase therapy work more effectively in certain groups of patients?, c) does rhDNase therapy work in the long term? and d) what is the cost-effectiveness of rhDNase therapy?

METHODS

A structured rapid review with modelling and cost-effectiveness calculations. Electronic searches were carried out to identify randomised controlled trials (RCTs), systematic reviews, epidemiological and economic information. Databases searched included Cochrane Library, Medline, Healthstar, Embase, PreMedline and NHS Economic Evaluation Database (NHS EED). Exclusion criteria were trials of very short duration (14 days or less) and those which looked at CF patients with severe lung disease. Open label extensions providing information on longer term outcomes were included.

RESULTS

Nine published RCTs were identified, although only one met the inclusion criteria. This large RCT was of good methodological quality, and shows that treatment with rhDNase over a 6-month period improves lung function, and decreases the risk of respiratory exacerbations. Expert opinion suggests that there are identifiable subgroups of patients showing improvement, little or no change, and deterioration after treatment with rhDNase. However, the best supporting evidence for this comes from a retrospective case series, showing that response to rhDNase is highly variable, and that early improvement was a good predictive marker for long-term benefit. Evidence for the long-term impact of rhDNase is not yet available from any RCTs. A simplified model was therefore developed to estimate the decline in lung function for patients treated with rhDNase, compared with those who were not treated. From this model it appears that the continued use of rhDNase over the lifetime of a CF patient might extend their life expectancy by 2 years. If treatment is limited to a subgroup of patients with moderate lung disease who respond to treatment, the continued use of rhDNase might extend their life expectancy by 7 years. Using the model, the discounted cost per life year gained for all patients is estimated at approximately pound52 500, with a range of between approximately pound25 000-57 000 from sensitivity analysis. For the subgroup of patients, the discounted cost per life year gained is estimated at approximately pound16 000, with a range of between approximately pound18 000-36 600 from sensitivity analysis.

CONCLUSIONS

Although there is short-term evidence that the use of rhDNase improves lung function and decreases the risk of respiratory exacerbations, at present there is no evidence from RCTs to indicate whether this effect is sustained over a longer time period, or whether rhDNase is associated with a reduction in mortality. RCTs to date have been of insufficient duration to answer important questions about long term outcomes, particularly the effects of rhDNase on lung function, respiratory exacerbations and mortality. Further long-term research is needed, with economic analysis to evaluate the long term cost-effectiveness of rhDNase. Research is also needed to identify, in advance, which patients would benefit most from this expensive treatment.

Volunteer assistance in the treatment of chronic alcoholism

Chronic alcoholics often have great difficulty in adjusting their lifestyle to accommodate the goals agreed upon in treatment. A 16-week behavioral self-management program, which emphasized creating lifestyle changes in the community, was offered to 193 clients. To assist in the process of treatment delivery, half of the clients were offered the support of trained community volunteers during the treatment program. To give volunteers a time period in which to to meet and start working with their clients, only those clients who completed at least the first 4 weeks of the 16-week program (N = 106) were included in the evaluation. Independent follow-up was conducted over a 12-month period. A significant reduction in alcohol consumption was found for clients of both the volunteer-support (VS; N = 52) and the office-based (OB; N = 54) groups; this reduction was maintained over the 12 months of review, with no major differences found between groups. Volunteers rated high on particular characteristics assisted the client more effectively during treatment than those rated low. The variability in hours spent between volunteer-client pairs appeared to mask any main effects, and also the length of the contact period with the volunteer was too short. It is recommended that the use of volunteers be evaluated further by extending the client contact time into the follow-up period.

Modulation of apolipoprotein D and apolipoprotein E expression in rat hippocampus after entorhinal cortex lesion

Apolipoprotein (apo) D is a member of the lipocalin family of proteins. Although its physiological function is unknown, apoD is thought to transport one or more small hydrophobic ligands. A second apolipoprotein, apoE is known to play an important role in lipid transport, and apoE genetic polymorphism has been shown to be associated with susceptibility to Alzheimer's disease. Both apoD and apoE are expressed in the central nervous system (CNS) and both proteins accumulate at sites of peripheral nerve injury due to increased local synthesis. The two proteins may have overlapping or complementary functions within nervous tissue. In order to define the role of apoD within the CNS, we have studied the regional distribution of apoD and apoE mRNA and protein within the normal rat brain and the changes in apoD and apoE expression in the hippocampus of rats after entorhinal cortex lesion (EC lesion). Within the brains of normal rats, apoD expression in the hippocampus was as high as 180-fold that of the liver. ApoD mRNA levels in other areas of the rat brain ranged from 40 to 120 times the hepatic levels. The distribution of apoE gene expression within the brain was similar to that of apoD, but was much lower than hepatic apoE expression. When rats were subjected to EC lesion, the apoD message increased by 54% at 4 days post lesion (DPL) in the ipsilateral region of hippocampus while apoE mRNA levels (ipsilateral and contralateral) decreased by 43%. At 6 to 8 DPL apoD mRNA in the ipsilateral hippocampus remained elevated (42% above controls) whereas the apoE mRNA levels increased to about 15% above those of controls. At 14 and 31 DPL, both apoD and apoE expression was similar to controls. The increase in immunoreactive apoD in hippocampal extracts was more dramatic. At 1 DPL, immunoreactive apoD levels were already 16-fold higher than those in extracts of non-lesioned animals and, at 31 DPL, levels were still 8-fold higher than those of control animals. Finally, we have demonstrated that the levels of apoD in the brains of apoE-deficient mice are 50-fold those of wildtype control mice. ApoD clearly has an important function within the CNS in both normal and pathological situations.

Bacterial expression and purification of the Fab fragment of a monoclonal antibody specific for the low-density lipoprotein receptor-binding site of human apolipoprotein E

We report the bacterial expression and the purification of a monoclonal antibody (mAb) specific for an epitope that coincides with the LDL receptor (LDLr)-binding domain of human apolipoprotein E (apoE). This antibody resembles the LDLr in its primary structure and its specificity for apoE variants. The recombinant Fab (rFab) fragment of mAb 2E8, consisting of the entire light chain and the Fd portion of the heavy chain, was expressed in Escherichia coli and purified to homogeneity. Purification was facilitated by including a five-histidine carboxyl-terminal extension on the Fd chain. A 5- to 10-fold difference in yield of the antibody was observed when the plasmid was expressed in two different strains of E. coli. Typically 2-6 mg of rFab per liter of culture medium was recovered in the periplasm of the TG1 strain and less than 1 mg was recovered in the periplasm of the XL1-Blue strain. Culture temperatures above 35 degrees C or inclusion of sucrose in the medium reduced rFab yields. The 2E8 rFab was indistinguishable from Fab prepared from 2E8 hybridoma-generated IgG with respect to its affinity and fine specificity. We are using this system to express a panel of 2E8 variant Fabs that will be used as probes to establish the structural features responsible for the binding of apoE to the LDLr.