Spinal cord stimulation for chronic pain of neuropathic or ischaemic origin: systematic review and economic evaluation

OBJECTIVES

This report addressed the question 'What is the clinical and cost-effectiveness of spinal cord stimulation (SCS) in the management of chronic neuropathic or ischaemic pain?'

DATA SOURCES

Thirteen electronic databases [including MEDLINE (1950-2007), EMBASE (1980-2007) and the Cochrane Library (1991-2007)] were searched from inception; relevant journals were hand-searched; and appropriate websites for specific conditions causing chronic neuropathic/ischaemic pain were browsed. Literature searches were conducted from August 2007 to September 2007.

REVIEW METHODS

A systematic review of the literature sought clinical and cost-effectiveness data for SCS in adults with chronic neuropathic or ischaemic pain with inadequate response to medical or surgical treatment other than SCS. Economic analyses were performed to model the cost-effectiveness and cost-utility of SCS in patients with neuropathic or ischaemic pain.

RESULTS

From approximately 6000 citations identified, 11 randomised controlled trials (RCTs) were included in the clinical effectiveness review: three of neuropathic pain and eight of ischaemic pain. Trials were available for the neuropathic conditions failed back surgery syndrome (FBSS) and complex regional pain syndrome (CRPS) type I, and they suggested that SCS was more effective than conventional medical management (CMM) or reoperation in reducing pain. The ischaemic pain trials had small sample sizes, meaning that most may not have been adequately powered to detect clinically meaningful differences. Trial evidence failed to demonstrate that pain relief in critical limb ischaemia (CLI) was better for SCS than for CMM; however, it suggested that SCS was effective in delaying refractory angina pain onset during exercise at short-term follow-up, although not more so than coronary artery bypass grafting (CABG) for those patients eligible for that surgery. The results for the neuropathic pain model suggested that the cost-effectiveness estimates for SCS in patients with FBSS who had inadequate responses to medical or surgical treatment were below 20,000 pounds per quality-adjusted life-year (QALY) gained. In patients with CRPS who had had an inadequate response to medical treatment the incremental cost-effectiveness ratio (ICER) was 25,095 pounds per QALY gained. When the SCS device costs varied from 5000 pounds to 15,000 pounds, the ICERs ranged from 2563 pounds per QALY to 22,356 pounds per QALY for FBSS when compared with CMM and from 2283 pounds per QALY to 19,624 pounds per QALY for FBSS compared with reoperation. For CRPS the ICERs ranged from 9374 pounds per QALY to 66,646 pounds per QALY. If device longevity (1 to 14 years) and device average price (5000 pounds to 15,000 pounds) were varied simultaneously, ICERs were below or very close to 30,000 pounds per QALY when device longevity was 3 years and below or very close to 20,000 pounds per QALY when device longevity was 4 years. Sensitivity analyses were performed varying the costs of CMM, device longevity and average device cost, showing that ICERs for CRPS were higher. In the ischaemic model, it was difficult to determine whether SCS represented value for money when there was insufficient evidence to demonstrate its comparative efficacy. The threshold analysis suggested that the most favourable economic profiles for treatment with SCS were when compared to CABG in patients eligible for percutaneous coronary intervention (PCI), and in patients eligible for CABG and PCI. In these two cases, SCS dominated (it cost less and accrued more survival benefits) over CABG.

CONCLUSIONS

The evidence suggested that SCS was effective in reducing the chronic neuropathic pain of FBSS and CRPS type I. For ischaemic pain, there may need to be selection criteria developed for CLI, and SCS may have clinical benefit for refractory angina short-term. Further trials of other types of neuropathic pain or subgroups of ischaemic pain, may be useful.

Docetaxel for the adjuvant treatment of early nodepositive breast cancer: a single technology appraisal

This paper presents a summary of the evidence review group (ERG) report into the clinical and cost-effectiveness of docetaxel for the adjuvant treatment of early node-positive breast cancer based upon the manufacturer’s submission to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The manufacturer’s scope restricts the intervention to docetaxel in combination with doxorubicin and cyclophosphamide (TAC), and the comparator to anthracycline-based chemotherapy. Based on the BCIRG 001 trial, the submitted evidence shows that TAC is associated with superior disease-free and overall survival at 5 years compared with the anthracycline-based regimen FAC. The absolute risk reduction in patients treated with TAC compared with those treated with FAC was 7% for disease-free survival and 6% for overall survival. However, TAC was associated with significantly greater toxicity than FAC. There is also evidence that docetaxel, in an unlicensed sequential regimen FEC100-T, is associated with superior diseasefree and overall survival at 5 years compared with FEC100. An economic model was developed by the manufacturer based on the BCIRG 001 trial. This generated central estimates of the cost per life-year gained and cost per quality-adjusted lifeyear (QALY) gained of TAC compared with FAC of £7900 and £9800 respectively. The manufacturer’s submission predicts a cost-effectiveness of £15,000–£20,000 per QALY gained for TAC compared with E-CMF (epirubicin in sequential therapy with cyclophosphamide, methotrexate, and fluorouracil), and estimates the cost-effectiveness of FEC100-T to be £8200 per QALY compared with FEC100. Taking into account a number of issues identified by the ERG this may generate higher estimates of cost-effectiveness, but these are unlikely to exceed £35,000 per QALY gained. Importantly, FAC is not commonly used in clinical practice in the UK and, therefore, the submitted evidence does not indicate whether TAC is superior to the anthracycline-based regimens that are in common use (FEC or E-CMF). The indirect comparisons presented suggest that the economic case for TAC in comparison to current UK practice may not be proven. The manufacturer’s submission failed to record evidence of three serious adverse events in patients receiving docetaxel with doxorubicin or to mention the concern of the European Medicines Agency regarding TAC’s long-term adverse events. The guidance issued by NICE in June 2006 as a result of the STA states that docetaxel, when given concurrently with doxorubicin and cyclophosphamide (the TAC regimen), is recommended as an option for the adjuvant treatment of women with early nodepositive breast cancer.

Ezetimibe monotherapy for cholesterol lowering in 2,722 people: systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

To study the evidence on the efficacy and safety of ezetimibe monotherapy for the treatment of primary (heterozygous familial and non-familial) hypercholesterolaemia.

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

Eleven electronic bibliographic databases covering the biomedical, scientific and grey literature were searched from inception and supplemented by contact with experts in the field. Two reviewers independently determined the eligibility of RCTs, with a minimum treatment duration of 12 weeks, which compared ezetimibe monotherapy (10 mg per day) with placebo.

RESULTS

In the absence of data from clinical outcome trials, surrogate endpoints such as changes in lipid concentrations were used as indicators of clinical outcomes. A meta-analysis of eight randomized, double-blind, placebo-controlled trials (all 12 weeks) showed that ezetimibe monotherapy was associated with a statistically significant mean reduction in LDL cholesterol (from baseline to endpoint) of -18.58%, (95% CI: -19.67 to -17.48, P < 0.00001) compared with placebo. Significant (P < 0.00001) changes were also found in total cholesterol (-13.46%, 95% CI: -14.22 to -12.70), HDL cholesterol (3.00%, 95% CI: 2.06-3.94) and triglyceride levels (-8.06%, 95% CI: -10.92 to -5.20). Ezetimibe monotherapy appeared to be well tolerated with a safety profile similar to placebo.

CONCLUSIONS

In a meta-analysis restricted to short-term trials in hypercholesterolaemia, significant potentially favourable changes in lipid and lipoprotein levels relative to baseline occurred with ezetimibe monotherapy. Further long-term studies with cardiovascular and other clinical outcome data are needed to assess the efficacy and safety of ezetimibe more fully.

The pregnancy-induced increase in baseline circulating growth hormone in rats is not induced by ghrelin

The elevation in baseline circulating growth hormone (GH) that occurs in pregnant rats is thought to arise from increased pituitary GH secretion, but the underlying mechanism remains unclear. Distribution, Fourier and algorithmic analyses confirmed that the pregnancy-induced increase in circulating GH in 3-week pregnant rats was due to a 13-fold increase in baseline circulating GH (P < 0.01), without any significant alteration in the parameters of episodic secretion. Electron microscopy revealed that pregnancy resulted in a reduction in the proportion of mammosomatotrophs (P < 0.01) and an increase in type II lactotrophs (P < 0.05), without any significant change in the somatotroph population. However, the density of the secretory granules in somatotrophs from 3-week pregnant rats was reduced (P < 0.05), and their distribution markedly polarised; the granules being grouped nearest the vasculature. Pituitary GH content was not increased, but steady-state GH mRNA levels declined progressively during pregnancy (P < 0.05). In situ hybridisation revealed that pregnancy was accompanied by a suppression of GH-releasing hormone mRNA expression in the arcuate nuclei (P < 0.05) and enhanced somatostatin mRNA expression in the periventricular nuclei (P < 0.05), an expression pattern normally associated with increased GH feedback. Although gastric ghrelin mRNA expression was elevated by 50% in 3-week pregnant rats (P < 0.01), circulating ghrelin, GH-secretagogue receptor mRNA expression and the GH response to a bolus i.v. injection of exogenous ghrelin were all largely unaffected during pregnancy. Although trace amounts of 'pituitary' GH could be detected in the placenta with radioimmunoassay, significant GH-immunoreactivity could not be observed by immunohistochemistry, indicating that rat placenta itself does not produce 'pituitary' GH. Although not excluding the possibility that the pregnancy-associated elevation in baseline circulating GH could arise from alternative extra-pituitary sources (e.g. the ovary), our data indicate that this phenomenon is most likely to result from a direct alteration of somatotroph function.

Cost-effectiveness of oxaliplatin and capecitabine in the adjuvant treatment of stage III colon cancer

For many years, the standard treatment for stage III colon cancer has been surgical resection followed by 5-fluorouracil in combination with folinic acid (5-FU/LV). Ongoing clinical trial evidence suggests that capecitabine and oxaliplatin (in combination with 5-FU/LV) may improve disease-free survival and overall survival when compared against 5-FU/LV alone in the adjuvant setting. This study evaluates the cost-effectiveness profiles of these two regimens in comparison to standard chemotherapy, using evidence from two international randomised controlled trials. Survival modelling techniques were employed to extrapolate survival curves from the two trials in order to estimate the long-term benefits of alternative treatment options over the remaining lifetime of patients. The health economic analysis suggests that capecitabine is expected to produce greater health gains at a lower cost than 5-FU/LV. Oxaliplatin in combination with 5-FU/LV is estimated to cost pounds 2970 per additional QALY gained when compared to 5-FU/LV alone. Future research should attempt to elucidate uncertainties concerning the optimal roles of capecitabine and/or oxaliplatin in the adjuvant setting in order to achieve the maximum level of clinical benefit.

Systematic review and economic evaluation of a long-acting insulin analogue, insulin glargine

OBJECTIVES

To evaluate the use of insulin glargine in its licensed basal-bolus indication in terms of both clinical and cost-effectiveness.

DATA SOURCES

Electronic databases.

REVIEW METHODS

A systematic review of the literature, involving a range of databases, was performed to identify all papers relating to insulin glargine.

RESULTS

Nineteen studies met the inclusion criteria but full reports were available for only six. For type 1 diabetes patients, insulin glargine appears to be more effective than neutral protamine Hagedorn (NPH) in reducing fasting blood glucose (FBG) but not in reducing glycosylated haemoglobin (HbA1c) and there is some evidence that both insulins are as effective as each other in both FBG and HbA1c control. For type 2 patients for whom oral antidiabetic agents provide inadequate glycaemic control, there is no evidence that insulin glargine is more effective than NPH in reducing either FBG or HbA1c and some evidence that both insulins are as effective as each other in both FBG and HbA1c control. Evidence for control of hypoglycaemia is equivocal. In studies where insulin glargine is demonstrated to be superior to NPH in controlling nocturnal hypoglycaemia, this may be only apparent when compared with once-daily NPH and not twice-daily NPH. Further, this superiority of glargine over NPH in the control of nocturnal hypoglycaemia may relate to one formulation of insulin glargine (HOE901[80]) and not another (HOE901[30]). There is no conclusive evidence that insulin glargine is superior to NPH in controlling symptomatic hypoglycaemia and severe hypoglycaemia. Insufficient data are available to conclude whether insulin glargine is different from each of the commonly used NPH dosing regimens: once daily and more than once daily. Given the lack of a published evidence base for the cost-effectiveness of insulin glargine, the economic review concentrates on a review of the industry submission and an amended model. Three economic models are provided in the submission, two relating to type 1 diabetes and one relating to type 2 diabetes. All three models compare the cost--utility of insulin glargine against NPH insulin. In general, the structures of the models are poor and in all three models, mistakes relating to assumptions and calculations have been made. The assessment team believe that the cost per QALY estimates generated by the Aventis model may be an underestimate for several reasons. The cost-effectiveness of insulin glargine in both type 1 and type 2 diabetes is highly sensitive to the amount of utility associated with reducing the fear of hypoglycaemia.

CONCLUSIONS

The evidence suggests that, compared with NPH insulin, insulin glargine is effective in reducing the number of nocturnal hypoglycaemic episodes, especially when compared with once-daily NPH. There appears to be no improvement in long-term glycaemic control and therefore insulin glargine is unlikely to reduce the incidence of the long-term microvascular and cardiovascular complications of diabetes. Further research into insulin glargine is needed that addresses the quality of life issues associated with fear of hypoglycaemia and also the economic impact of balance of HbA1c control and incidence of hypoglycaemia achieved in practice. Studies examining the economic evidence on insulin glargine should be published.

Clinical effectiveness and cost-effectiveness of pioglitazone and rosiglitazone in the treatment of type 2 diabetes: a systematic review and economic evaluation

OBJECTIVES

To evaluate the use of pioglitazone and rosiglitazone, in terms of both clinical and cost-effectiveness in the treatment of type 2 diabetes.

DATA SOURCES

Electronic databases and the reference lists of relevant articles, in addition 14 health services research-related resources were consulted via the Internet.

REVIEW METHODS

A systematic review of the literature, involving a range of databases, was performed to identify all papers relating to the glitazones. The methodological quality of the included randomised controlled trials (RCTs) was assessed using the Jadad method. A generic proforma for the critical appraisal of modelling studies in health economics was used in systematically reviewing the economic assessment studies identified. This was supplemented by a detailed review of the disease-specific factors within the studies. Where possible, key outcomes were compared. Readers should note that information from the sponsor's submission was submitted in confidence to the National Institute for Clinical Excellence (NICE). Such information was made available to the NICE Appraisals Committee, but has been removed from this version of the report.

RESULTS

Of the 1272 studies identified, nine studies met the inclusion criteria. The clinical evidence available showed that glitazones reduce glycosylated haemoglobin by approximately 1%, and are more effective at higher doses than at lower doses. Glitazone treatment is associated with weight gain. No published data were available on the long-term effects of glitazone use. No prospective RCTs were found comparing pioglitazone to rosiglitazone, but the available evidence indicated that the two treatments had similar effects. There are no published economic studies on either pioglitazone or rosiglitazone. Economic evaluations for both glitazones were provided by the manufacturers. Sensitivity analyses undertaken by the assessment team suggest that the cost per quality-adjusted life-year (QALY) of rosiglitazone is most sensitive to dosage and treatment effect, that is, the effect of rosiglitazone on beta-cell function and insulin sensitivity. In the two scenarios where rosiglitazone is compared with metformin and sulfonylurea combination therapy, the cost-effectiveness of rosiglitazone switches from around 10,000 pounds per QALY to being dominated by the comparator strategy. Since the baseline estimate of cost-effectiveness is not robust to changes in the treatment effect and is reliant on the many assumptions included within the metabolic and long-term economic models, caution should be used in interpreting the baseline result.

CONCLUSIONS

The clinical evidence available showed that glitazones can reduce glycosylated haemoglobin; however there were no peer-reviewed data available on the long-term effects of their use or any prospective RCTs found comparing pioglitazone with rosiglitazone. No published economic studies on either pioglitazone or rosiglitazone were found, although sensitivity analyses undertaken by the assessment team suggest that the cost per QALY of rosiglitazone is most sensitive to dosage and treatment effect. It is suggested that research already undertaken in this area should be published, preferably in peer-reviewed journals. Direct head-to-head comparisons of the glitazones in combination with metformin or sulfonylurea would be helpful. The current licence arrangements do not allow for routine use of the glitazones in triple oral combination therapy or in combination with insulin. Evidence is emerging of use of the glitazones within such combinations; therefore, prospective RCTs would be useful. These studies could examine short-term transition strategies and longer term management. The impact of the glitazones in delaying transfer to insulin and the impact on long-term outcomes should also be considered for investigation.

Liquid-based cytology in cervical screening: an updated rapid and systematic review and economic analysis

OBJECTIVES

To update an earlier published report reviewing the effectiveness and cost-effectiveness of liquid-based cytology (LBC).

DATA SOURCES

Electronic bibliographic databases, relevant articles, sponsor submissions and various health services research-related resources.

REVIEW METHODS

The selected data were reviewed and assessed with respect to the quality of the evidence. Pooled estimates of the parameters of interest were derived from the original and the updated studies. Meta-analyses were undertaken where appropriate. The mathematical model developed for the original rapid review of LBC was adapted to synthesise the updated data to estimate costs, survival and quality-adjusted survival of patients tested using LBC and using Papanicolaou (Pap) smear testing. Cost data from published sources were incorporated into the above model to allow economic, as well as clinical, implications of treatment to be assessed. The primary incremental cost-effectiveness ratio is the cost per life year gained (LYG), although estimates of the cost per quality-adjusted life-year (QALY) gained are also presented. A sensitivity analysis was undertaken to identify the key parameters that determine the cost-effectiveness of the treatments, with the objective of identifying how robust the results of the economic analysis are, given the current level of evidence.

RESULTS

From the evidence available, it is likely that the LBC technique will reduce the number of false-negative test results. Modelling analyses undertaken as part of this study indicate that this would reduce the incidence of invasive cancer. There is now more evidence to support improvements emanating from the use of LBC screening in terms of a reduced number of unsatisfactory specimens and a decrease in the time needed to obtain the smear samples. The estimated annual gross cost of consumables and operating equipment, and other one-off conversion costs associated with introducing the new technique, will be between 17 British pounds and 38 British pounds million in England and Wales, depending on the LBC system and the configuration of the service. Analyses based on models of disease natural history, conducted in this study, showed that conventional Pap smear screening was extendedly dominated by LBC (LBC was always more cost-effective than conventional Pap smear testing over the same screening interval). Comparing LBC across alternative screening intervals gave a cost-effectiveness of under 10,000 British pounds per LYG when screening was undertaken every 3 years. The cost-effectiveness results were relatively stable under most conditions, although if screening outcomes such as borderline results and colposcopy are assumed to induce even small amounts of disutility then LBC screening at 5-yearly intervals may be the most cost-effective option.

CONCLUSIONS

This updated analysis provides more certainty with regard to the potential cost-effectiveness of LBC compared with conventional Pap smear testing. However, there is uncertainty regarding the relative effectiveness (and cost-effectiveness) of the two main LBC techniques. Further research in the area of utility assessment may be worthwhile and possibly a full cost-effectiveness study of LBC based on a trial of its introduction in a low-prevalence population, although the results of the modelling analysis provide a robust argument that LBC is a cost-effective alternative to conventional cervical cancer screening. A randomised comparison of the two main techniques may also be useful.

A systematic review and economic evaluation of magnetic resonance cholangiopancreatography compared with diagnostic endoscopic retrograde cholangiopancreatography

OBJECTIVES

To compare the clinical and cost-effectiveness of magnetic resonance cholangiopancreatography (MRCP) with diagnostic endoscopic retrograde cholangiopancreatography (ERCP) for the investigation of biliary obstruction.

DATA SOURCES

Electronic bibliographic databases, the reference lists of relevant articles and various health services research-related resources.

REVIEW METHODS

The data sources were searched and selected studies were assessed using quality criteria. In total, 28 prospective diagnostic studies were identified reporting several suspected conditions plus one of patient satisfaction. Analyses were then performed to establish sensitivities, specificities, likelihood ratios and confidence intervals. The relative cost-effectiveness of adopting MRCP scanning in the investigation of the biliary tree was undertaken using a probabilistic economic model.

RESULTS

The median sensitivity for choledocholithiasis (13 studies) was 93% and the median specificity 94%. The median likelihood ratio for a positive value was 15.75 and for a negative value 0.08. Reported sensitivities for malignancy were somewhat lower, ranging from 81 to 86%, and specificities ranged from 92 to 100%. There was some evidence that MRCP is an accurate diagnostic test in comparison to ERCP, although the quality of studies was moderate. Claustrophobia prevented at least some patients from having MRCP in ten of the 28 studies. The other 18 studies did not mention claustrophobia. The probability of avoiding unnecessary diagnostic ERCP is estimated at 30%. These patients could avoid the unnecessary risk of complications and death associated with diagnostic ERCP, and substantial cost saving would be gained. The overall expected cost saving associated with MRCP is GBP149; the overall expected gain in quality-adjusted life-year is estimated at 0.011.

CONCLUSIONS

There is some evidence that MRCP is an accurate investigation compared with diagnostic ERCP, although the values for malignancy compared with choledocholithiasis were somewhat lower. The quality of studies was moderate. The limited evidence on patient satisfaction showed that patients preferred MRCP to diagnostic ERCP. The estimated clinical and economic impacts of diagnostic MRCP versus diagnostic ERCP are very favourable. The baseline estimate is that MRCP may both reduce cost and result in improved quality of life outcomes compared with diagnostic ERCP. Further research is suggested to compare MRCP and diagnostic ERCP with final diagnosis and also with the full range of target conditions; to examine patient satisfaction and ways of reducing problems with claustrophobia; to look at protocols to help identify who could most benefit from MRCP or ERCP; to assess the relative need and urgency of patient access to magnetic resonance imaging services, and also to determine how demand would affect availability and potential cost savings.

Clinical effectiveness and cost-effectiveness of neonatal screening for inborn errors of metabolism using tandem mass spectrometry: a systematic review

OBJECTIVES

To evaluate the clinical and cost-effectiveness of tandem mass spectrometry (MS)-based neonatal screening for inborn errors of metabolism (IEM).

DATA SOURCES

Fourteen electronic bibliographic databases covering biomedical, science, economic and grey literature, the reference lists of relevant articles and abstracts of conference proceedings and 18 health services research-related resources.

REVIEW METHODS

This review is an update of two previous HTA reports of neonatal screening for IEM. These reports have been updated by a systematic review of published research (between 1995 and January 2002) on neonatal screening of inherited metabolic disorders using tandem MS. This was supplemented by a search for economic literature and the application of a modelling exercise to investigate the economics of using tandem MS within a neonatal screening programme in the UK.

RESULTS

Evidence from the reviews of IEM found that the UK screening programme for phenylketonuria (PKU) was well established and there was universal agreement that neonatal screening for PKU was justified. Of the many other disorders that can be detected by tandem MS, the best candidate condition for a new screening programme was medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency. For many other IEM that can be detected by tandem MS, robust clinical evidence was limited. Cost-effectiveness analysis using economic modelling indicated that substituting the use of tandem MS for existing technologies for the screening of PKU alone could not be justified. However, results from the economic modelling indicate that the addition of screening for MCAD deficiency as part of a neonatal screening programme for PKU using tandem MS would be economically attractive. Using an operational range of 50,000-60,000 specimens per system per year, the mean incremental cost for PKU and MCAD deficiency screening combined using tandem MS from the model was -23,312 British pounds for each cohort of 100,000 neonates screened. This cost saving is associated with a mean incremental gain of 59 life-years. Additional economic modelling using the available evidence does not support including other inherited metabolic diseases within a neonatal screening programme at present.

CONCLUSIONS

The evidence appears to support the introduction of tandem MS into a UK neonatal screening programme for PKU and MCAD deficiency combined. Tandem MS has the potential for simultaneous multi-disease screening using a single analytical technique. Although the marginal cost of extending the programme to include other conditions may be relatively small, the application of this new technology to PKU and MCAD deficiency screening does not imply the wholesale inclusion of all disorders detectable by tandem MS. It is suggested that the primary focus of further research should be on the long-term effectiveness of treatment strategies on adverse outcomes (disabilities and impairments) under conventional management and the potential impact of early diagnosis using tandem MS.

The clinical and cost-effectiveness of pulsatile machine perfusion versus cold storage of kidneys for transplantation retrieved from heart-beating and non-heart-beating donors

OBJECTIVES

To evaluate the clinical and cost-effectiveness of machine perfusion (MP) compared to cold storage (CS), as a means of preserving kidneys prior to transplantation. Transplantation of kidneys from both heart-beating donors (HBDs) and non-heart-beating donors (NHBDs) is considered. Finally to review whether the use of MP can allow valid testing of kidney viability prior to transplantation.

DATA SOURCES

Fifteen electronic bibliographic databases were searched. The reference lists of relevant articles and sponsor submissions were hand searched and various health service research-related resources were consulted via the Internet.

REVIEW METHODS

A literature search was undertaken to identify relevant studies and a meta-analysis performed on the studies that had appropriate comparator groups and reported sufficient data. A structured review examined tests of viability of kidneys on MP. Economic modelling was used to determine the cost-effectiveness and cost-utility of MP.

RESULTS

The meta-analysis suggested that the use of MP, as compared with CS, is associated with a relative risk of delayed graft function (DGF) of 0.804 (95% confidence limits 0.672 to 0.961). There was no evidence to suggest that this effect is different in kidneys taken from HBDs as opposed to NHBDs. Meta-analysis of 1-year graft survival data showed no significant effect, but the studies, even when aggregated, were severely underpowered with respect to the likely impact on graft survival. The size of effects demonstrated were in line with those predicted by an indirect model of graft survival based on the association of DGF with graft loss. The economic assessment indicated that it is unlikely that in the UK health setting complete cost recovery will be obtained from a reduction in the incidence of DGF. The probability that MP is cheaper and more effective than CS in the long term was estimated at around 80% for NHBD recipients and 50-60% for HBD recipients. Flow characteristics of the perfusate of kidneys undergoing MP may be an indicator of kidney viability, but data were inadequate to calculate the sensitivity and specificity of any test based on this. The concentration of alpha-glutathione-S-transferase (a marker of cell damage) in the perfusate may be the basis of a valid test. A threshold of 2800 micrograms/100 g gave a sensitivity of 93% and specificity of 33% (and hence a likelihood ratio of 1.41).

CONCLUSIONS

The baseline analysis indicated that in the long-term MP would be expected to be cheaper and more effective than CS for both HBD and NHBD recipients. A definitive study of the clinical benefit of MP in order to establish its effect on DGF and longer term graft survival would be valuable, together with an economic evaluation of the benefits. While direct evidence relating to improvements in graft survival would be preferable, the small predicted improvement indicates that a very large sample size would be required. In addition to seeking direct evidence of the impact on DGF, research quantifying the impact of DGF on graft survival in this technology is required. Research is also needed to establish whether a valid test (or combination of tests) of kidney viability can be developed.

The role of modelling in prioritising and planning clinical trials

OBJECTIVES

To identify the role of modelling in planning and prioritising trials. The review focuses on modelling methods used in the construction of disease models and on methods for their analysis and interpretation.

DATA SOURCES

Searches were initially developed in MEDLINE and then translated into other databases.

REVIEW METHODS

Systematic reviews of the methodological and case study literature were undertaken. Search strategies focused on the intersection between three domains: modelling, health technology assessment and prioritisation.

RESULTS

The review found that modelling can extend the validity of trials by: generalising from trial populations to specific target groups; generalising to other settings and countries; extrapolating trial outcomes to the longer term; linking intermediate outcome measures to final outcomes; extending analysis to the relevant comparators; adjusting for prognostic factors in trials; and synthesising research results. The review suggested that modelling may offer greatest benefits where the impact of a technology occurs over a long duration, where disease/technology characteristics are not observable, where there are long lead times in research, or for rapidly changing technologies. It was also found that modelling can inform the key parameters for research: sample size, trial duration and population characteristics. One-way, multi-way and threshold sensitivity analysis have been used in informing these aspects but are flawed. The payback approach has been piloted and while there have been weaknesses in its implementation, the approach does have potential. Expected value of information analysis is the only existing methodology that has been applied in practice and can address all these issues. The potential benefit of this methodology is that the value of research is directly related to its impact on technology commissioning decisions, and is demonstrated in real and absolute rather than relative terms; it assesses the technical efficiency of different types of research. Modelling is not a substitute for data collection. However, modelling can identify trial designs of low priority in informing health technology commissioning decisions.

CONCLUSIONS

Good practice in undertaking and reporting economic modelling studies requires further dissemination and support, specifically in sensitivity analyses, model validation and the reporting of assumptions. Case studies of the payback approach using stochastic sensitivity analyses should be developed. Use of overall expected value of perfect information should be encouraged in modelling studies seeking to inform prioritisation and planning of health technology assessments. Research is required to assess if the potential benefits of value of information analysis can be realised in practice; on the definition of an adequate objective function; on methods for analysing computationally expensive models; and on methods for updating prior probability distributions.

The cost-effectiveness of nCPAP treatment in patients with moderate-to-severe obstructive sleep apnoea

The demand for diagnostic and therapeutic services for obstructive sleep apnoea syndrome (OSAS) showed marked growth during the 1990s. This paper analyses the long-term cost-effectiveness of nasal continuous positive airway pressure (nCPAP) treatment in comparison to conventional null treatment. A Markov model was used to represent the natural history of OSAS based upon published evidence. Utility values came from a survey of OSAS patients. Data on health costs were collected from hospitals in the Basque Country, Spain. The incremental cost-effectiveness ratio of nCPAP treatment is <6,000 Euros per quality-adjusted life year. On disaggregated analysis, nCPAP treatment accounts for 86% of incremental costs; 84% of incremental effectiveness is attributable to improved quality of life. Treatment of obstructive sleep apnoea syndrome with nasal continuous positive airway pressure has a cost-effectiveness that is in line with that of other commonly funded treatments such as antihypertensive drugs. The key clinical benefit of nasal continuous positive airway pressure treatment is improvement in the quality of life of patients with obstructive sleep apnoea syndrome. This benefit is also precisely the one for which the evidence base is strongest. The remaining uncertainties concerning the impact of nasal continuous positive airway pressure on long-term mortality have only a relatively small impact on the economics of treatment.

A systematic review of the clinical effectiveness of pioglitazone in the treatment of type 2 diabetes mellitus

BACKGROUND

Pioglitazone is a member of a recently developed class of glucose-lowering agents, the thiazolidinediones, used in the treatment of type 2 diabetes mellitus. In the United States, it is approved for use both as monotherapy and in combination with metformin, a sulfonylurea, or insulin; in Europe, it is approved for use in combination with metformin or a sulfonylurea but not insulin.

OBJECTIVE

This article presents a systematic review of the published literature on the effectiveness of pioglitazone in the treatment of type 2 diabetes, both as monotherapy and in combination with other antidiabetic agents.

METHODS

The peer-reviewed English- and foreign-language literature was searched using MEDLINE, PubMED, EMBASE, Science Citation Index, the Cochrane Database of Systematic Reviews, the Cochrane Controlled Trials Register, the UK National Health Service Centre for Reviews and Dissemination databases, and the Office of Health Economics Health Economic Evaluations Database. Searches were not limited to specific publication types, study designs, dates, or languages. The latest search was performed in March 2001. For a trial to be included in the review, at least 1 outcome measure had to involve the effects of pioglitazone on glycemic control or cardiovascular risk factors, or its side effects. Because of the heterogeneity of studies, no formal meta-analysis was performed.

RESULTS

Eleven studies met the inclusion criteria, 6 involving pioglitazone monotherapy and 5 involving combination therapy. Full reports were available for only 6 of the 11 studies. No studies directly compared pioglitazone with other antidiabetic drugs. Both as monotherapy and in combination therapy, pioglitazone produced decreases in blood glucose levels (up to 95 mg/dL) and glycosylated hemoglobin (up to 2.6%). At doses of > or = 30 mg/d, pioglitazone was associated with reductions in triglyceride levels (-30-70 mg/dL) and increases in high-density lipoprotein cholesterol (HDL-C) levels (-4-5 mg/dL). Pioglitazone treatment was associated with significant weight gain (up to 4 kg over 16 weeks). Adverse effects included mild edema (in up to 11.7% of patients) and a clinically nonsignificant decrease in hemoglobin concentrations. Abnormal results on liver function testing were no more common in treated patients than in control groups.

CONCLUSIONS

Pioglitazone has been shown to reduce blood glucose levels in patients with type 2 diabetes. Although the observed decreases in triglyceride levels and increases in HDL-C levels could be expected to lead to a reduction in cardiovascular risk, the effects of weight gain may counteract this benefit. The evidence suggests that the preferred role for pioglitazone may be as an adjunct to metformin or a sulfonylurea in patients whose condition is not well controlled with monotherapy and for whom a metformin-sulfonylurea combination is contraindicated. There is a need for large-scale, long-term studies comparing the effectiveness of combination therapy that includes pioglitazone with that of other combinations of antidiabetic drugs.

Structure-activity relationship investigations of a potent and selective benzodiazepine oxytocin antagonist

We have investigated the structure-activity relationships of the 1- and 3-substituents and replacements of the 5-phenyl group of GW405212X 1, a potent selective oxytocin antagonist. The effect of these modifications on oxytocin binding antagonism and on pharmacokinetic parameters is reported.