Antioxidants in the chemoprevention of colorectal cancer and colorectal adenomas in the general population: a systematic review and meta-analysis

AIM

Antioxidants, such as vitamin A, C and E, selenium and β-carotene, have been proposed as possible agents in the chemoprevention of colorectal cancer and have been the subject of recent trials and reviews. This review aimed to assess the present evidence on the effect of antioxidants on the incidence of colorectal neoplasms in the general population.

METHOD

A systematic review of randomized controlled trials was undertaken comparing antioxidants alone or in combination with other agents vs placebo. The following databases were searched for published and unpublished literature: Cochrane Library, MEDLINE, PreMEDLINE, CINAHL, EMBASE, Web of Science, and Biological Abstracts and Research Registers. Studies were quality appraised and extracted. Meta-analysis was performed.

RESULTS

Twelve studies were identified as relevant. In the nine comparing antioxidants with no antioxidants (n=148 922), there was no difference in the incidence of colorectal cancer [relative risk (RR) 1.00, 95% confidence interval (CI) 0.88-1.13]. One study assessed the effect of antioxidants on adenoma formation (n=15 538) and did not demonstrate a statistically significant effect (RR 1.47, 95% CI 0.97-2.23). Of 14 discrete analyses for different combinations of antioxidants, only one reported a statistically significant increase in relative risk of adenoma formation in participants receiving vitamin E (RR 1.74, 95% CI 1.09-1.79, P=0.02) or vitamin E plus β-carotene (RR 1.63, 95% CI 1.01-2.63, P=0.04). Effectiveness did not seem to differ between healthy populations, participants with cardiovascular risk factors or populations exposed to smoking or asbestos.

CONCLUSION

The review demonstrates that antioxidants (vitamin A, C and E, selenium and β-carotene), as single agents, in combination with other antioxidants or in combination with other agents, are not effective in the chemoprevention of colorectal neoplasia in the general population. This questions their involvement in future randomized controlled trials of chemoprevention in colorectal cancer.

Evidence Review Group approaches to the critical appraisal of manufacturer submissions for the NICE STA process: a mapping study and thematic analysis

BACKGROUND

The National Institute for Health and Clinical Excellence (NICE) single technology appraisal (STA) process was set up as a rapid way to appraise new technologies for use within the NHS in England and Wales and has been in place since 2005.

OBJECTIVES

This study had five primary objectives: (1) to provide a map of the STA process to date; (2) to identify current approaches to the critical appraisal of manufacturers' submissions (MSs) by Evidence Review Groups (ERGs); (3) to identify recurring themes in clarification letters sent to manufacturers; (4) to provide recommendations for possible alternative approaches to be used in the critical appraisal process; and (5) to revise the current ERG report template.

DATA SOURCES

Data for the mapping of the STA process were obtained from the NICE website (www.nice.org.uk). Data for the analyses of the ERG reports and clarification letters were taken from the reports and letters themselves.

REVIEW METHODS

For the mapping, a spreadsheet was developed to collect data on 22 predefined variables related to timings and outcomes. Simple descriptive statistics were used to analyse the data. For the thematic analysis, a documentary analysis of 30 ERG reports was undertaken. Data on key elements of the MSs, the processes undertaken by ERGs and the strengths and weaknesses of MSs were extracted. A framework of a priori themes was developed. Data were extracted, coded and analysed according to a framework approach. Twenty-one clarification letters were examined and data were extracted using a set of codes to cover report quality, systematic review methods and clinical/economic issues. The current ERG report template was modified and sent to the current ERG teams for comment. All comments were considered and formed the basis for further revisions to the template.

RESULTS

Ninety-five STAs were included in the mapping exercise. Many STAs were subject to delay or cancellation for a variety of reasons. The ERG reports highlighted the strengths and weaknesses of MSs to the STA process. Thematic analysis of these data offered a means of clarifying and describing these aspects of the submissions. This analysis generated five themes: process, reporting, satisfaction of objectives, reliability and validity of findings, and content. Points from clarification letters were analysed and presented in four main categories: report quality, systematic review methods, clinical data analysis and economic data analysis.

LIMITATIONS

Nearly all data were obtained from the NICE website; therefore, any errors in the data on the website will be reflected in the mapping analysis presented in this report. Missing data for the mapping exercise limit the generalisability of the findings. Analyses were limited to what was reported in the ERG reports and the clarification letters.

CONCLUSIONS

Guidance suggested for manufacturers will help to ensure that more appropriate submissions are received in the future while recommendations provided for ERG teams will help to guide teams to ensure that reporting methods are transparent.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The clinical effectiveness and safety of prophylactic retinal interventions to reduce the risk of retinal detachment and subsequent vision loss in adults and children with Stickler syndrome: a systematic review

BACKGROUND

Stickler syndrome, also known as hereditary progressive arthro-ophthalmopathy, is an inherited progressive disorder of the collagen connective tissues. Manifestations include short-sightedness, cataracts, retinal problems leading to retinal detachment and possible blindness. This is principally the case among individuals with type 1 Stickler Syndrome. It is the most commonly identified inherited cause of retinal detachment in childhood. However, there is no consensus regarding best practice and no current guidelines on prophylactic interventions for this population.

OBJECTIVES

The aim of this systematic review was to assess the evidence for the clinical effectiveness and safety of primary prophylactic interventions for the prevention of retinal detachment in previously untreated eyes without retinal detachment in patients with Stickler syndrome. The primary outcome of interest was retinal detachment post prophylaxis.

DATA SOURCES

A systematic search was made of 11 databases of published and unpublished literature, which included MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing and Allied Health Literature and The Cochrane Library. There was no restriction by language or date. The references of all included studies were checked for further relevant citations and authors of studies with potentially relevant data were also contacted.

REVIEW METHODS

Two reviewers double-screened all titles and abstracts of the citations retrieved by the search to identify studies that satisfied the inclusion criteria. Both reviewers also independently extracted and quality assessed all included studies. A narrative synthesis was performed.

RESULTS

The literature search identified 1444 unique citations, of which four studies satisfied the inclusion criteria. The two principal studies were both retrospective cohort studies with control groups in populations with type 1 Stickler syndrome. One study evaluated 360° cryotherapy (n = 204) and the other focal or circumferential laser treatment (n = 22). Both studies reported a statistically significant difference in the rate of retinal detachment per eye between the groups receiving prophylaxis and the controls. However, both studies were subject to a high risk of bias. The results of the two supporting studies of Wagner-Stickler patients were either relatively inconsistent or unreliable. No study reported any major or long-term complications associated with the interventions. Despite the weaknesses of the evidence, the rate of retinal detachment in the intervention groups, especially the cryotherapy group, was lower than the rate either experienced in the study control groups or reported in other studies of untreated Stickler syndrome populations not exposed to prophylaxis.

CONCLUSIONS

Only 360° cryotherapy and focal and circumferential laser treatment have been evaluated for the type 1 Stickler syndrome population, and then only by a single retrospective, controlled, cohort study in each case. Both of these studies report a significant difference between intervention and control groups (principally no treatment) and no major or long-term side effects or complications. However, there is a high risk of bias within these two studies, so the relative effectiveness of either intervention is uncertain.

FUTURE WORK

A service priority is to determine reliably the prevalence of Stickler syndrome, i.e. how many individuals have type 1 or type 2 Stickler syndrome, and their risk of retinal detachment and subsequent blindness. A non-randomised, prospective cohort comparison study, in which eligible participants are treated, followed-up and analysed in one of three study arms, for no treatment, laser therapy or cryotherapy, would potentially offer further certainty in terms of the relative efficacy of both prophylaxis versus no prophylaxis and cryotherapy versus laser therapy than is possible with the currently available data. Alternatively, continued follow-up and analysis of existing study data, and data collection from relevant sample populations, are required to assess the long-term risks of blindness, retinal detachment and prophylaxis.

FUNDING

This study was funded by the National Institute for Health Research Health Technology Assessment programme.

Radical prostatectomy outcome when performed with PSA above 20 ng/ml

Many centres currently do not offer radical prostatectomy (RP) to men with high-risk localised prostate cancer due to concerns regarding poor outcome, despite evidence to the contrary. We identified 18 men undergoing RP with serum PSA >20 ng/ml (high-risk by National Comprehensive Cancer Network definition) and minimum follow-up of 12 years (mean 13.5). Mean preoperative PSA was 37.0 ng/ml (Range 21.1-94.0). Prostatectomy pathology reported extracapsular disease in 16 (88.9%), positive surgical margins in 15 (83%) and positive pelvic lymph nodes in 5 (27.8%). Overall and cancer-specific survival at 5 and 10-years was 83.3%, 88.2%, 72% and 76.5% respectively. With complete follow-up 11 (61.1%) are alive, and 5 (27.8%) avoided any adjuvant therapy. Complete continence (defined as no involuntary urine leakage and no use of pads) was achieved in 60%, with partial continence in the remainder. We conclude that surgery for this aggressive variant of localised prostate cancer can result in satisfactory outcome.

Chemoprevention of colorectal cancer: systematic review and economic evaluation

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer in the UK: incidence increases with age, median age at diagnosis being over 70 years. Approximately 25% of cases occur in individuals with a family history of CRC, including 5% caused by familial adenomatous polyposis (FAP) or hereditary non-polyposis CRC (HNPCC). Most develop from adenomatous polyps arising from the intestine lining. Individuals with these polyps undergo polypectomy and are invited for endoscopic surveillance. Screening via faecal occult blood testing has been rolled out across the UK.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of drug and micronutrient interventions for the prevention of CRC and/or adenomatous polyps. Interventions considered include: non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin and cyclo-oxygenase-2 (COX-2) inhibitors; folic acid; calcium; vitamin D and antioxidants (including vitamin A, vitamin C, vitamin E, selenium and beta-carotene). Chemoprevention was assessed in the general population, in individuals at increased risk of CRC, and in individuals with FAP or HNPCC.

DATA SOURCES

A systematic review identified randomised controlled trials (RCTs) assessing drug and nutritional agents for the prevention of CRC or adenomatous polyps. A separate search identified qualitative studies relating to individuals' views, attitudes and beliefs about chemoprevention. MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, CINAHL, the Cochrane Database of Systematic Reviews, Cochrane CENTRAL Register of Controlled Trials, DARE, NHS-EED (NHS Economic Evaluation Database), HTA database, Science Citation Index, BIOSIS previews and the Current Controlled Trials research register were searched in June 2008. Data were extracted by one reviewer and checked by a second.

REVIEW METHODS

The synthesis methods used were systematic review and meta-analysis for RCTs and qualitative framework synthesis for qualitative studies. A health economic model was developed to assess the cost-effectiveness of chemoprevention for two populations with different levels of risk of developing CRC: the general population and an intermediate-risk population.

RESULTS

The search identified 44 relevant RCTs and six ongoing studies. A small study of aspirin in FAP patients produced no statistically significant reduction in polyp number but a possible reduction in polyp size. There was a statistically significant 21% reduction in risk of adenoma recurrence [relative risk (RR) 0.79, 95% confidence interval (CI) 0.68 to 0.92] in an analysis of aspirin versus no aspirin in individuals with a history of adenomas or CRC. In the general population, a significant 26% reduction in CRC incidence was demonstrated in studies with a 23-year follow-up (RR 0.74, 95% CI 0.57 to 0.97). Non-aspirin NSAID use in FAP individuals produced a non-statistically significant reduction in adenoma incidence after 4 years of treatment and follow-up and reductions in polyp number and size. In individuals with a history of adenomas there was a statistically significant 34% reduction in adenoma recurrence risk (RR 0.66, 95% CI 0.60 to 0.72) and a statistically significant 55% reduction in advanced adenoma incidence (RR 0.45, 95% CI 0.35 to 0.58). No studies assessed the effect of non-aspirin NSAIDs in the general population. There were no studies of folic acid in individuals with FAP or HNPCC. There was no significant effect of folic acid versus placebo on adenoma recurrence (RR 1.16, 95% CI 0.97 to 1.39) or advanced adenoma incidence in individuals with a history of adenomas. In the general population there was no significant effect of folic acid on risk of CRC (RR 1.13, 95% CI 0.77 to 1.64), although studies were of relatively short duration. Calcium use by FAP patients produced no significant reduction in polyp number or disease progression. In individuals with a history of adenomas there was a statistically significant 18% reduction in risk of adenoma recurrence (RR 0.82, 95% CI 0.69 to 0.98) and a non-significant reduction in risk of advanced adenomas (RR 0.77, 95% CI 0.50 to 1.17). In the general population there was no significant effect of calcium on risk of CRC (RR 1.08, 95% CI 0.87 to 1.34), although studies were of relatively short duration. There were no studies of antioxidant use in individuals with FAP or HNPCC, and in individuals with a history of adenomas no statistically significant differences in relative risk of adenoma recurrence were found. In the general population there was no difference in incidence of CRC (RR 1.00, 95% CI 0.88 to 1.13) with antioxidant use compared with no antioxidant use. Twenty studies reported qualitative findings concerning chemoprevention. People are more likely to use NSAIDs if there is a strong perceived need. Perceptions of risk and benefit also influence decision-making and use. People have fewer concerns about using antioxidants or other supplements, but their perception of the benefits of these agents is less well-defined. The model analysis suggested that the most cost-effective age-range policy in the general population would be to provide chemoprevention to all individuals within the general population from age 50 to 60 years. The use of aspirin in addition to screening within the general population is likely to result in a discounted cost per life-year gained of around 10,000 pounds and a discounted cost per quality-adjusted life-year (QALY) gained of around 23,000 pounds compared with screening alone. In the intermediate-risk group the most economically viable age-range policy would be to provide chemoprevention to individuals following polypectomy aged 61 to 70 years. Calcium is likely to have a discounted cost per QALY gained of around 8000 pounds compared with screening alone. Although aspirin in addition to screening should be more effective and less costly than screening alone, under the current assumptions of benefits to harms of aspirin and calcium, aspirin is expected to be extendedly dominated by calcium.

LIMITATIONS

Whilst a number of studies were included in the review, the duration of follow-up was generally insufficient to detect an effect on cancer incidence. Given the uncertainties and ambiguities in the evidence base, the results of the health economic analysis should be interpreted with caution.

CONCLUSIONS

Aspirin and celecoxib may reduce recurrence of adenomas and incidence of advanced adenomas in individuals with an increased risk of CRC and calcium may reduce recurrence of adenomas in this group. COX-2 inhibitors may decrease polyp number in patients with FAP. There is some evidence for aspirin reducing the incidence of CRC in the general population. Both aspirin and NSAIDs are associated with adverse effects so it will be important to consider the risk-benefit ratio before recommending these agents for chemoprevention. The economic analysis suggests that chemoprevention has the potential to represent a cost-effective intervention, particularly when targeted at intermediate-risk populations following polypectomy.

School-linked sexual health services for young people (SSHYP): a survey and systematic review concerning current models, effectiveness, cost-effectiveness and research opportunities

BACKGROUND

Report based on a service-mapping study and a systematic review concerning sexual health services for young people, either based in or closely linked to schools.

OBJECTIVES

To identify current forms of school-based sexual health services (SBSHS) and school-linked sexual health services (SLSHS) in the UK, review and synthesise existing evidence from qualitative and quantitative studies concerning the effectiveness, acceptability and cost-effectiveness of these types of service and to identify potential areas for further research.

DATA SOURCES

Electronic databases were searched from 1985 onwards. For published material: the Cochrane Library (1991-), MEDLINE, PREMEDLINE (2007-), CINAHL, EMBASE, AMED, ASSIA (1987-), IBSS, ERIC, PsycINFO, Science Citation Index (SCI) and Social Sciences Citation Index. For unpublished material and grey literature: the Social Care Institute of Excellence Research Register; the National Research Register (1997-), ReFeR; Index to Theses, and HMIC.

REVIEW METHODS

A service-mapping questionnaire was circulated to school nurses in all parts of the UK, and semistructured telephone interviews with service coordinators in NHS and local authority (LA) roles were conducted. An evidence synthesis was performed based on a systematic review of the quantitative evidence about service effectiveness, qualitative evidence about user and professional views and a mixed-methods synthesis. A proof-of-concept model for assessing cost-effectiveness was drawn up.

RESULTS

Three broad types of UK sexual health service provision were identified. Firstly, SBSHS staffed by school nurses, offering 'minimal' or 'basic' levels of service. Secondly, SBSHS and SLSHS staffed by a multiprofessional team, but not medical practitioners, offering 'basic' or 'intermediate' levels of service. Thirdly, SBSHS and SLSHS staffed by a multiprofessional team, including medical practitioners offering 'intermediate' or 'comprehensive' levels of service. The systematic review showed that SBSHS are not associated with higher rates of sexual activity among young people, nor with an earlier age of first intercourse. There was evidence to show positive effects in terms of reductions in births to teenage mothers, and in chlamydial infection rates among young men, although this evidence coming primarily from the USA. Therefore, the findings need to be tested in relation to UK-based services. Also evidence to suggest that broad-based, holistic service models, not restricted to sexual health, offer the strongest basis for protecting young people's privacy and confidentiality, countering perceived stigmatisation, offering the most comprehensive range of products and services, and maximising service uptake. Findings from the mapping study also indicate that broad-based services, which include medical practitioner input within a multiprofessional team, meet the stated preferences of staff and of young people most clearly. Partnership-based developments of this kind also conform to the broad policy principles embodied in the Every Child Matters framework in the UK and allied policy initiatives. However, neither these service models nor narrower ones have been rigorously evaluated in terms of their impact on the key outcomes of conception rates and sexually transmitted infection (STI) rates, in the UK or in other countries. Therefore, appropriate data were not found to support cost-effectiveness modelling.

LIMITATIONS

Low response rate to the questionnaire. Scotland, Wales and Northern Ireland were under-represented. Also, the distinction made in the questionnaire between 'general health' and 'sexual health' services did not prove robust.

CONCLUSIONS

There is no single, dominant service model in the UK. The systematic review demonstrated that the evidence base for these services remains limited and uneven, and draws largely on US studies. Qualitative research is needed to develop robust process and outcome indicators for the evaluation of SLSHS/SBSHS in the UK. These indicators could then be used both in local evaluations, and in large, longitudinal studies of service effectiveness and cost-effectiveness. Future research should examine the impact of the differing types of services currently evolving in the UK, encompassing school-based and school-linked models, as well as models with and without medical practitioner involvement.

Paediatric flexible bronchoscopy and its indications

Paediatric flexible bronchoscopy (F.B.) with bronchoalveolar lavage (B.A.L.) is an increasingly important investigation. Retrospective review of 180 FB performed over a 5 year period by a single operator was undertaken. Common indications included recurrent lower respiratory tract infections (n = 92, 51%), persistent atelectasis (n = 43, 24%), persistent infiltrates (n = 18, 10%) and persistent consolidation (n = 17, 9%). Normal airway anatomy was identified in the majority (n = 154, 85.5%). Bronchomalacia was identified in 22 cases (12%). Thick purulent secretions were seen in 40 bronchoscopies (22%). Commonest organisms cultured on BAL were H. influenza (n = 22, 12.2%), Streptococcus Pneumoniae (n = 18, 10%) and Staph aureus (n = 9, 5%). Cytomegalo virus (C.M.V.), (n = 4, 2%), candida (n = 1, 0.5%) and aspergillus fumigatus were identified (n = 7, 4%). Bronchoscopic findings frequently guided management (n = 90, 51%). No significant complications occurred. Flexible bronchoscopy procedure, patient and equipment care were in adherence with best practice guidelines. Paediatric F.B. is a safe and useful procedure when clinically indicated.

Meta-analysis: folic acid in the chemoprevention of colorectal adenomas and colorectal cancer

BACKGROUND

Folic acid has been identified as a possible agent for the chemoprevention of colorectal cancer.

AIM

To assess the effectiveness of folic acid in reducing the recurrence of adenomas (precursors of colorectal cancer) among populations with a history of adenomas and the incidence of colorectal cancer within average-risk populations.

METHODS

Systematic review of randomized controlled trials comparing folic acid alone, or with other agents, vs. placebo. Eight databases were searched for relevant trials. Meta-analysis was performed.

RESULTS

The literature search retrieved 3785 citations. Six studies met the inclusion criteria. Meta-analysis of three studies in individuals with a history of adenomas showed no statistically significant difference in the relative risk of adenoma recurrence (RR 0.93, P = 0.27). A sensitivity analysis of the two higher quality trials changed the direction of effect (RR 1.16, P = 0.11). Meta-analysis of three trials in general populations demonstrated no statistically significant effect on the relative risk of colorectal cancer (RR 1.13, P = 0.54). In all three analyses, outcome event rates were higher in individuals receiving folic acid.

CONCLUSION

There is no evidence that folic acid is effective in the chemoprevention of colorectal adenomas or colorectal cancer for any population.

Dabigatran etexilate for the prevention of venous thromboembolism in patients undergoing elective hip and knee surgery: a single technology appraisal

This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of dabigatran etexilate (DBG) for the prevention of venous thromboembolism (VTE) in patients undergoing elective hip and knee surgery based upon a review of the manufacturer's submission to the NICE as part of the single technology appraisal (STA) process. The submission's evidence came from three reasonable-quality trials comparing DBG with enoxaparin, and a comparison of DBG with fondaparinux based on the relative efficacy and safety as derived from a mixed treatment comparison (MTC) meta-analysis. DBG (220 mg and 150 mg once daily) is not inferior to enoxaparin (40 mg once daily and 30 mg twice daily) in terms of major VTE or VTE-related events (secondary outcome). Meta-analysis shows that 220 mg DBG is not inferior to enoxaparin (40 mg once daily or 30 mg twice daily) in reducing total VTE and all-cause mortality (primary outcome) in total hip or knee replacement, whereas there is uncertainty around the clinical effectiveness of 150 mg DBG for this outcome. In the MTC analysis DBG compared favourably with the other interventions, with the exception of extended enoxaparin and fondaparinux. The adverse event profile was not significantly different in those receiving DBG and those receiving enoxaparin. The submitted two-phase economic model compares DBG with enoxaparin and fondaparinux in total hip and knee replacement. The model structure is appropriate and the model assumptions are reasonable. The health states, costs, utilities and recurrence rates used are considered to be appropriate for the required analysis. The model estimated that at the licensed dose of 220 mg once daily DBG dominates enoxaparin in both total hip replacement and total knee replacement and that at the lower dose of 150 mg once daily DBG dominates enoxaparin in total hip replacement and enoxaparin dominates DBG in total knee replacement. DBG is less cost-effective than fondaparinux in total hip replacement at both doses; the cost per quality-adjusted life-year of fondaparinux versus DBG is 11,111 pounds and 6857 pounds for the higher and lower doses of DBG respectively. In total knee replacement, both DBG doses are dominated by fondaparinux. For DBG versus all comparators in all cases the cost-effectiveness results are based on small incremental cost and health benefits. Weaknesses of the submitted evidence include that methods used for screening studies, data extraction and applying quality assessment criteria to included studies, as well as key details of trials included in the MTC, were not adequately described. In addition, some input parameters into the modelling process are incorrect. The ERG was unable to correct all of these mistakes and the impact on the model results is therefore unknown. The National Institute for Health and Clinical Excellence guidance issued as a result of the STA states that DBG is recommended as an option for the primary prevention of VTE events in adults who have undergone elective total hip or knee replacement surgery.

Dabigatran etexilate for the prevention of venous thromboembolism in patients undergoing elective hip and knee surgery: a single technology appraisal

This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of dabigatran etexilate (DBG) for the prevention of venous thromboembolism (VTE) in patients undergoing elective hip and knee surgery based upon a review of the manufacturer’s submission to the NICE as part of the single technology appraisal (STA) process. The submission’s evidence came from three reasonable-quality trials comparing DBG with enoxaparin, and a comparison of DBG with fondaparinux based on the relative efficacy and safety as derived from a mixed treatment comparison (MTC) meta-analysis. DBG (220 mg and 150 mg once daily) is not inferior to enoxaparin (40 mg once daily and 30 mg twice daily) in terms of major VTE or VTE-related events (secondary outcome). Meta-analysis shows that 220 mg DBG is not inferior to enoxaparin (40 mg once daily or 30 mg twice daily) in reducing total VTE and all-cause mortality (primary outcome) in total hip or knee replacement, whereas there is uncertainty around the clinical effectiveness of 150 mg DBG for this outcome. In the MTC analysis DBG compared favourably with the other interventions, with the exception of extended enoxaparin and fondaparinux. The adverse event profile was not significantly different in those receiving DBG and those receiving enoxaparin. The submitted two-phase economic model compares DBG with enoxaparin and fondaparinux in total hip and knee replacement. The model structure is appropriate and the model assumptions are reasonable. The health states, costs, utilities and recurrence rates used are considered to be appropriate for the required analysis. The model estimated that at the licensed dose of 220 mg once daily DBG dominates enoxaparin in both total hip replacement and total knee replacement and that at the lower dose of 150 mg once daily DBG dominates enoxaparin in total hip replacement and enoxaparin dominates DBG in total knee replacement. DBG is less cost-effective than fondaparinux in total hip replacement at both doses; the cost per quality-adjusted life-year of fondaparinux versus DBG is £11,111 and £6857 for the higher and lower doses of DBG respectively. In total knee replacement, both DBG doses are dominated by fondaparinux. For DBG versus all comparators in all cases the cost-effectiveness results are based on small incremental cost and health benefits. Weaknesses of the submitted evidence include that methods used for screening studies, data extraction and applying quality assessment criteria to included studies, as well as key details of trials included in the MTC, were not adequately described. In addition, some input parameters into the modelling process are incorrect. The ERG was unable to correct all of these mistakes and the impact on the model results is therefore unknown. The National Institute for Health and Clinical Excellence guidance issued as a result of the STA states that DBG is recommended as an option for the primary prevention of VTE events in adults who have undergone elective total hip or knee replacement surgery.

Opposite Neural Effects of the Main Psychoactive Ingredients of Cannabis- Neural Basis for Potential Therapeutic Effects of Cannabidiol

There is considerable interest in the therapeutic potential of Cannabidiol (CBD), the second most abundant component of Cannabis. While delta-9-THC, the main psychoactive ingredient of cannabis, impairs memory and induces anxiety and psychotic symptoms acutely and increases the risk of psychotic disorders in regular cannabis users, CBD does not impair memory, may have anxiolytic and possibly antipsychotic effects. Hence, we compared directly the acute neural effects of these two active ingredients of cannabis, by combining pharmacological challenge with fMRI. Using a double-blind, repeated measures design and oral challenge with 10mg of delta-9-THC, 600mg of CBD or placebo in 15 healthy volunteers, we examined whether delta-9-THC and CBD have opposing effects on the neural substrates of verbal memory and fear processing and whether they also have opposing effects on the neural substrates of anxiety and psychotic symptoms induced by delta-9-THC. Delta-9-THC induced anxiety and psychotic symptoms acutely while there was a trend for a reduction in anxiety but no change in psychotic symptoms with CBD. During the memory task, delta-9-THC attenuated and CBD increased activation in the striatum bilaterally. Effect of delta-9-THC on striatal activation was inversely correlated with the psychotic symptoms induced by it concomitantly. During the processing of fearful faces, delta-9-THC increased and CBD attenuated activation in the amygdala and these effects correlated with their anxiogenic and anxiolytic effects respectively. These opposing effects of CBD on the key neural substrates for psychotic symptoms and anxiety induced by delta-9-THC may suggest its possible therapeutic role in countering these conditions.

The cost-effectiveness of bevacizumab in the first-line treatment of metastatic colorectal cancer in England and Wales

BACKGROUND

Bevacizumab is a humanised monoclonal antibody, which has demonstrated significant activity in metastatic colorectal cancer. The aim of this study is to estimate the cost-effectiveness of adding bevacizumab to chemotherapy for patients with untreated metastatic colorectal cancer.

METHODS

A decision-analytic model was developed to estimate the lifetime costs and benefits of adding bevacizumab to irinotecan plus FU/LV (IFL) or 5-FU/LV alone. Effectiveness outcomes, health utilities and resource use data were derived from recent bevacizumab RCTs and from the literature.

RESULTS

Adding bevacizumab to IFL costs approximately pound62,857 per QALY gained. Adding bevacizumab to 5-FU/LV costs approximately pound88,436 per QALY gained. The acquisition cost of bevacizumab is a key determinant of its cost-effectiveness. The probability that bevacizumab has a cost-effectiveness ratio that is better than pound30,000 per QALY gained is close to zero.

CONCLUSIONS

Given high acquisition costs in relation to clinical benefits, bevacizumab is unlikely to represent a cost-effective use of NHS resources.

Hormonal therapies for early breast cancer: systematic review and economic evaluation

OBJECTIVES

To establish the clinical and cost-effectiveness of aromatase inhibitors (AIs) anastrozole, letrozole and exemestane compared with tamoxifen in the adjuvant treatment of early oestrogen receptor-positive breast cancer in postmenopausal women.

DATA SOURCES

Major electronic databases and three trials registers were searched from May to June 2005. Three conference abstract databases were searched in December 2005. Industry submissions.

REVIEW METHODS

Studies evaluating the clinical effectiveness of AIs against 5 years' tamoxifen treatment were included and critically appraised. The review of the health economics of AIs in early breast cancer in comparison with standard therapies included a review of existing economic evaluations of the relevant therapies, a critique of each of the economic evaluations submitted to the National Institute for Health and Clinical Excellence (NICE) by pharmaceutical manufacturers and a detailed explanation of the methodologies and results of the authors' economic model. The three treatment strategies (primary adjuvant therapy, unplanned switch therapy and extended adjuvant therapy) were considered separately within the authors' economic analysis.

RESULTS

A meta-analysis of three trials found a significant difference in overall survival when an unplanned anastrozole switching strategy was compared with 5 years' tamoxifen. Significant improvements in overall survival are yet to be demonstrated in other strategies. Compared with 5 years' tamoxifen, disease-free survival (disease recurrence or death from any cause) was significantly improved in the primary adjuvant setting with anastrozole and letrozole, and with an exemestane switching strategy. Other trials did not report this outcome. Breast cancer recurrence (censoring death as an event) was significantly improved with primary adjuvant anastrozole and letrozole, anastrozole switching, extended adjuvant anastrozole or letrozole. The AIs and tamoxifen have different side-effect profiles, with tamoxifen responsible for small but statistically significant increases in endometrial cancer and, sometimes, thromboembolic events and stroke. AIs show a trend towards increases in osteoporosis, the statistical significance of which increases with follow-up time. The absence of tamoxifen treatment also increases the risk of hypercholesterolaemia and cardiac events in postmenopausal women. There was no significant difference in overall health-related quality of life between standard treatment and either primary adjuvant anastrozole and extended adjuvant letrozole strategies. The cost-effectiveness results for AIs compared with tamoxifen in the primary adjuvant setting, are estimated to be between 21,000 pounds and 32,000 pounds per quality-adjusted life-year (QALY) based on an analysis over 35 years. There is currently no trial evidence for exemestane in this setting. The cost-effectiveness results for anastrozole and exemestane, compared with tamoxifen in the unplanned switching setting, are estimated to be 23,200 pounds and 19,200 pounds per QALY, respectively, based on an analysis over 35 years. There is currently no trial evidence for letrozole in this setting. In the extended adjuvant setting, the cost per QALY for letrozole compared with placebo is estimated to be 9800 pounds, based on an analysis over 35 years. All these results are considered to be conservative. In the base case it is assumed that the benefits of AIs over tamoxifen or placebo seen during the therapy period are gradually lost during the following 10 years. An alternative scenario, the 'benefits maintained' scenario, is tested in sensitivity analysis. Here it is assumed that following the treatment period the annual rate of recurrence in both arms is the same. This reduces the cost-effectiveness ratio by over 50%, to around 10,000-12,000 pounds, 5000 pounds and 3000 pounds in the primary adjuvant, unplanned switching and extended adjuvant setting, respectively. The limited evidence to date of benefits after the therapy period suggests that the 'benefits maintained' scenario may be realistic. The results from the economic analyses within the industry submissions are generally lower than the results from the authors' model and are close to or below 12,000 pounds in all three settings. The authors' analyses generally produce a lower estimate of QALY gain for the aromatase inhibitors, due to the more conservative assumption regarding benefits, along with differences in the utility values used in the their analysis.

CONCLUSIONS

On the basis of the current data and within their licensed indications, AIs can be considered clinically effective compared with standard tamoxifen treatment. However, their long-term effects, in terms of both benefits and harms, remain unclear. Under the conservative assumption that benefits gained by AIs during the treatment period are gradually lost over the following 10 years, the cost per QALY for AIs compared with tamoxifen is estimated to be between 21,000 pounds and 32,000 pounds in the primary adjuvant setting and around 20,000 pounds in the unplanned switch setting. The cost per QALY for AIs compared with placebo in the extended adjuvant setting is estimated to be around 10,000 pounds. Under the less conservative assumption that rates of recurrence are the same in both arms after the therapy period is complete, the incremental cost-effectiveness ratios are typically at least 50% lower, suggesting that AIs are likely to be considered cost-effective in all three settings. Understanding of the long-term treatment effects on cost-effectiveness is, however, incomplete. Data on the impact of AIs on survival are awaited from the majority of the trials to confirm whether or not the benefits seen in disease-free survival and recurrence rates are translated into overall survival benefit in the medium to long-term.

Systematic review and economic evaluation of bevacizumab and cetuximab for the treatment of metastatic colorectal cancer

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of bevacizumab and cetuximab in the treatment of individuals with metastatic colorectal cancer (CRC).

DATA SOURCES

Searches of main electronic databases were conducted in April and May 2005.

REVIEW METHODS

For the assessment of bevacizumab, trials were included if they recruited participants with untreated metastatic CRC for first-line treatment. Only trials comparing bevacizumab in combination with irinotecan and/or established fluorouracil (5-FU)-containing or releasing regimens given as first-line therapy were included. For the assessment of cetuximab, trials were included if they recruited participants with epidermal growth-factor receptor-expressing metastatic CRC who had previously failed irinotecan-including therapy. Independent cost-effectiveness models of bevacizumab and cetuximab were developed using survival modelling methods.

RESULTS

Adding bevacizumab to irinotecan in combination with 5-FU/folic acid (FA) plus irinotecan resulted in a statistically significant increase in median overall survival (OS) of 4.7 months. Adding bevacizumab to 5-FU/FA resulted in a non-significant increase in median OS of 3.7 months within one study and 7.7 months in another. Adding bevacizumab to irinotecan, fluorouracil and leucovorin (IFL) resulted in a statistically significant increase in median progression-free survival (PFS) of 4.4 months. Adding bevacizumab to 5-FU/FA resulted in a statistically significant increase in median PFS of 3.7 months, and a statistically significant increase in time to disease progression of 3.8 months compared to FU/FA alone. An overall tumour response rate of 44.8% was reported for bevacizumab plus IFL compared to 34.8% for IFL plus placebo. This addition was statistically significant. The addition of bevacizumab to 5-FU/FA resulted in a significant difference in tumour response rate within one study, but not another. Bevacizumab in combination with IFL or 5-FU/FA was observed to result in an increase of grade 3/4 adverse events. The independent health economic assessment suggests that the cost-effectiveness of bevacizumab plus IFL is unlikely to be better than pound 46,853 per life-year gained (LYG); the cost-utility of bevacizumab plus IFL is unlikely to be better than pound 62,857 per quality-adjusted life-year (QALY) gained. The cost-effectiveness of bevacizumab plus 5-FU/FA versus 5-FU/FA is unlikely to be better than pound 84,607 per LYG; the cost-utility of bevacizumab plus 5-FU/FA versus 5-FU/FA is unlikely to be better than pound 88,658 per QALY gained. A Phase II trial reported a median OS duration of 8.6 months for patients receiving cetuximab plus irinotecan, plus a median time to progression of 4.1 months, a tumour response rate of 22.9% and suggested that treatment with cetuximab in combination with irinotecan is associated with significantly more adverse events (any grade 3 or grade 4 adverse event) than cetuximab monotherapy. The single arm study of cetuximab plus irinotecan reported a median OS duration of 8.4 months, a median time to progression of 2.9 months and a tumour response rate of 15.2%. The cost-effectiveness model suggested that the expected survival duration of patients receiving cetuximab plus irinotecan is 0.79 years (9.5 months) when the proposed continuation rule is applied. In order for cetuximab plus irinotecan to achieve a cost-utility ratio of pound 30,000 per QALY gained, treatment with cetuximab plus irinotecan must provide an additional 0.65 life years (7.8 months) over treatment with active/best supportive care, implying that survival in the active/best supportive care group must be 0.14 life years (1.7 months) or less.

CONCLUSIONS

The trials indicate that bevacizumab in combination with 5-FU/FA, and bevacizumab in combination with IFL, is clinically effective in comparison to standard chemotherapy options for the first-line treatment of metastatic CRC. The health economic analysis suggests that the marginal cost-utility of bevacizumab plus IFL versus IFL is unlikely to be better than pound 62,857 per QALY gained, and the marginal cost-utility of bevacizumab plus 5-FU/FA versus 5-FU/FA is unlikely to be better than pound 88,658 per QALY gained. There is no direct evidence to demonstrate whether cetuximab in combination with irinotecan improves health-related quality of life or OS in comparison to active/best supportive care or oxaliplatin plus 5-FU/FA, although the evidence on tumour response rates suggests that cetuximab plus irinotecan has some clinical activity. While it is difficult to suggest whether cetuximab represents value for money, indirect comparisons suggest that the incremental cost-utility of cetuximab plus irinotecan is unlikely to be better than pound 30,000 per QALY gained. This review highlights a number of areas for further research, including clarifying the true impact of first-line bevacizumab in combination with irinotecan and/or infusional 5-FU/FA, without subsequent bevacizumab treatment following disease progression, on OS in patients with metastatic CRC who are representative of the typical population of CRC patients in England and Wales. Further research concerning the impact of therapies on health-related quality of life is essential.

Is smoking tobacco an independent risk factor for HIV infection and progression to AIDS? A systemic review

OBJECTIVES

To systematically review the evidence of the relation between smoking tobacco and HIV seroconversion and progression to AIDS.

METHODS

A systematic review was undertaken of studies to look at tobacco smoking as a risk factor for either HIV seroconversion or progression to AIDS.

RESULTS

Six studies were identified with HIV seroconversion as an outcome measure. Five of these indicated that smoking tobacco was an independent risk factor after adjusting for important confounders with adjusted odds ratios ranging from 1.6 to 3.5. 10 studies were identified using progression to AIDS as an end point of which nine found no relation with tobacco smoking.

CONCLUSIONS

Tobacco smoking may be an independent risk factor for HIV infection although residual confounding is another possible explanation. Smoking did not appear to be related to progression to AIDS although this finding may not be true in developing countries or with the longer life expectancies seen with highly active antiretroviral therapy.

Antibiotic resistance of retail food and human Campylobacter isolates on the island of Ireland from 2001-2002

The antimicrobial resistance profiles of Campylobacter isolates recovered from a range of retail food samples (n=374) and humans (n=314) to eight antimicrobial compounds were investigated. High levels of resistance in food C. jejuni isolates were observed for ceftiofur (58%), ampicillin (25%) and nalidixic acid (17%) with lower levels observed for streptomycin (7.9%) and chloramphenicol (8.3%). A total of 80% of human C. jejuni isolates were resistant to ceftiofur, while 17% showed resistance to ampicillin and nalidixic acid, 8.6% to streptomycin and 4.1% to chloramphenicol. Resistance to clinically relevant antimicrobials such as erythromycin, ciprofloxacin and tetracycline was 6.7, 12, and 15% respectively for all food isolates and was similar to corresponding resistance prevalences observed for human isolates, where 6.4, 12 and 13% respectively were found to be resistant. Comparisons of C. jejuni isolates in each location showed a high degree of similarity although some regional variations did exist. Comparison of total C. jejuni and C. coli populations showed minor differences, with C. jejuni isolates more resistant to ampicillin and ceftiofur. Multidrug resistance patterns showed some profiles common to human and clinical isolates.