D Wang

University of Birmingham, Birmingham, ENG, United Kingdom

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Publications (3)8.06 Total impact

  • D Wang, S Bayliss, C Meads
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    ABSTRACT: Respiratory syncytial virus (RSV) is a seasonal infectious disease, with epidemics occurring annually from October to March in the UK. It is a very common infection in infants and young children and can lead to hospitalisation, particularly in those who are premature or who have chronic lung disease (CLD) or congenital heart disease (CHD). Palivizumab (Synagis®, MedImmune) is a monoclonal antibody designed to provide passive immunity against RSV and thereby prevent or reduce the severity of RSV infection. It is licensed for the prevention of serious lower respiratory tract infection caused by RSV in children at high risk. While it is recognised that a policy of using palivizumab for all children who meet the licensed indication does not meet conventional UK standards of cost-effectiveness, most clinicians feel that its use is justified in some children. To use systematic review evidence to estimate the cost-effectiveness of immunoprophylaxis of RSV using palivizumab in different subgroups of children with or without CLD or CHD who are at high risk of serious morbidity from RSV infection. A systematic review of the literature and an economic evaluation was carried out. The bibliographic databases included the Cochrane Library [Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA)] and five other databases, from inception to 2009. Research registries of ongoing trials including Current Controlled Trials metaRegister, Clinical Trials.gov and the National Institute for Health Research Clinical Research Network Portfolio were also searched. Searches were conducted for prognostic and hospitalisation studies covering 1950-2009 (the original report searches conducted in 2007 covering the period 1950-2007 were rerun in August 2009 to cover the period 2007-9) and the database of all references from the original report was sifted to find any relevant studies that may have been missed. The risk factors identified from the systematic review of included studies were analysed and synthesised using stata. The base-case decision tree model developed in the original HTA journal publication [Health Technol Assess 2008;12(36)] was used to derive the cost-effectiveness of immunoprophylaxis of RSV using palivizumab in different subgroups of pre-term infants and young children who are at high risk of serious morbidity from RSV infection. Cost-effective spectra of prophylaxis with palivizumab compared with no prophylaxis for children without CLD/CHD, children with CLD, children with acyanotic CHD and children with cyanotic CHD were derived. Thirteen studies were included in this analysis. Analysis of 16,128 subgroups showed that prophylaxis with palivizumab may be cost-effective [at a willingness-to-pay threshold of £30,000/quality-adjusted life-year (QALY)] for some subgroups. For example, for children without CLD or CHD, the cost-effective subgroups included children under 6 weeks old at the start of the RSV season who had at least two other risk factors that were considered in this report and were born at 24 weeks gestational age (GA) or less, but did not include children who were > 9 months old at the start of the RSV season or had a GA of > 32 weeks. For children with CLD, the cost-effective subgroups included children < 6 months old at the start of the RSV season who were born at 28 weeks GA or less, but did not include children who were > 21 months old at the start of the RSV season. For children with acyanotic CHD, the cost-effective subgroups included children < 6 months old at the start of the RSV season who were born at 24 weeks GA or less, but did not include children who were > 21 months old at the start of the RSV season. For children with cyanotic CHD, the cost-effective subgroups included children < 6 weeks old at the start of the RSV season who were born at 24 weeks GA or less, but did not include children who were > 12 months old at the start of the RSV season. The poor quality of the studies feeding numerical results into this analysis means that the true cost-effectiveness may vary considerably from that estimated here. There is a risk that the relatively high mathematical precision of the point estimates of cost-effectiveness may be quite inaccurate because of poor-quality inputs. Prophylaxis with palivizumab does not represent good value for money based on the current UK incremental cost-effectiveness ratio threshold of £30,000/QALY when used unselectively in children without CLD/CHD or children with CLD or CHD. This subgroup analysis showed that prophylaxis with palivizumab may be cost-effective (at a willingness-to-pay threshold of £30,000/QALY) for some subgroups. In summary, the cost-effective subgroups for children who had no CLD or CHD must contain at least two other risk factors apart from GA and birth age. The cost-effective subgroups for children who had CLD or CHD do not necessarily need to have any other risk factors. Future research should be directed towards conducting much larger, better powered and better reported studies to derive better estimates of the risk factor effect sizes. This report was funded by the HTA programme of the National Institute for Health Research.
    Health technology assessment (Winchester, England). 01/2011; 15(5):iii-iv, 1-124.
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    ABSTRACT: To systematically review the effectiveness and cost-effectiveness of palivizumab for the prevention of respiratory syncytial virus (RSV) in children and examine prognostic factors to determine whether subgroups can be identified with important differences in cost-effectiveness. Bibliographic databases were searched from inception to March 2007 for literature on the effectiveness and cost-effectiveness of prophylaxis with palivizumab. The literature was systematically reviewed and current economic evaluations were analysed to identify which parameters were driving the different cost-effectiveness estimates. A probabilistic decision-analytical model was built to assess the cost-effectiveness of prophylaxis with palivizumab for children at risk of RSV infection and the parameters populated with the best estimates thought most applicable to the UK. We also constructed a new model, the Birmingham Economic Evaluation (BrumEE). Cost-effectiveness analyses were undertaken from both NHS and societal perspectives. Two randomised controlled trials (RCTs) were identified. Prophylaxis with palivizumab for preterm infants without chronic lung disease (CLD) or children with CLD resulted in a 55% reduction in RSV hospital admission: 4.8% (48/1002) in the palivizumab group and 10.6% (53/500) in the no prophylaxis group (p = 0.0004). Prophylaxis with palivizumab was associated with a 45% reduction in hospitalisation rate RSV among children with coronary heart disease (CHD). Hospitalisation rates for RSV were 5.3% (34/639) in the palivizumab group and 9.7% (63/648) in the no prophylaxis group (p = 0.003). Of existing economic evaluations, 3 systematic reviews and 18 primary studies were identified. All the systematic reviews concluded that the potential costs of palivizumab were far in excess of any potential savings achieved by decreasing hospital admission rates, and that the use of palivizumab was unlikely to be cost-effective in all children for whom it is recommended, but that its continued use for particularly high-risk children may be justified. The incremental cost-effectiveness ratios (ICERs) of the primary studies varied 17-fold for life-years gained (LYG), from 25,800 pounds/LYG to 404,900 pounds/LYG, and several hundred-fold for quality-adjusted life-years (QALYs), from 3200 pounds/QALY to 1,489,700 pounds/QALY for preterm infants without CLD or children with CLD. For children with CHD, the ICER varied from 5300 pounds/LYG to 7900 pounds/LYG and from 7500 pounds/QALY to 68,700 pounds/QALY. An analysis of what led to the discrepant ICERs showed that the assumed mortality rate for RSV infection was the most important driver. The results of the BrumEE confirm that palivizumab does not reach conventional levels of cost-effectiveness in any of the licensed indications if used for all eligible children. Prophylaxis with palivizumab is clinically effective for the reducing the risk of serious lower respiratory tract infection caused by RSV infection and requiring hospitalisation in high-risk children, but if used unselectively in the licensed population, the ICER is double that considered to represent good value for money in the UK. The BrumEE shows that prophylaxis with palivizumab may be cost-effective (based on a threshold of 30,000 pounds/QALY) for children with CLD when the children have two or more additional risk factors. Future research should initially focus on reviewing systematically the major uncertainties for patient subgroups with CLD and CHD and then on primary research to address the important uncertainties that remain.
    Health technology assessment (Winchester, England) 01/2009; 12(36):iii, ix-x, 1-86. · 4.03 Impact Factor
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    ABSTRACT: To investigate the clinical effectiveness and cost-effectiveness of naltrexone for relapse prevention in detoxified formerly opioid-dependent individuals compared with any strategy that does not use naltrexone, including treatment with placebo, other pharmacological treatments, psychosocial interventions or no treatment. Major electronic databases were searched from inception to September 2005. Selected studies were screened and quality assessed. Meta-analyses were carried out as appropriate. A decision-analytic model using Monte Carlo simulation was developed that compared naltrexone as an adjunctive therapy to no naltrexone. It assumed compliance rates that were not enhanced by contingent management rewards (because this is current UK practice). Utility values could not be identified from the literature and so were obtained by research specially commissioned from the Value of Health Panel. The methodological quality of the 26 randomised controlled trials (RCTs) that met the inclusion criteria was poor to moderate. The results suggest that naltrexone as maintenance therapy may be better than placebo in terms of retention in treatment, but this was not statistically significant. A meta-analysis of seven included RCTs gave the relative risk (RR) of loss of retention in treatment in the naltrexone arm as 0.94. The pooled hazard ratio (HR) reported in five of the RCTs for retention in treatment data followed up to 35 weeks was calculated as 0.90 in favour of naltrexone and also did not reach statistical significance. The risk of drug abuse in naltrexone versus placebo, with or without psychological support given in both arms, gave a pooled RR of 0.72, which was a statistically significant difference in favour of naltrexone. The pooled HR from three RCTs for opioid relapse-free rates was significantly different from placebo in favour of naltrexone 0.53; however, this fell off over time and may be of limited clinical significance. The RR of reimprisonment while on naltrexone therapy showed results in favour of naltrexone in the combined two studies of parolees or people on probation, but the number of participants was small. One study of 52 participants found that the difference in improvement score for risky sexual behaviour in the naltrexone group compared with the placebo group was not statistically significant. The adverse events data reported showed no significant difference between the naltrexone and placebo arms. The quality of the nine RCTs of interventions designed to increase retention with naltrexone was poor to moderate; however, all three different modalities of enhanced care showed some evidence of effectiveness. All of the contingency management programmes used incentive vouchers; the mean duration of treatment retention was 7.4 weeks for the contingency management intervention compared with 2.3-5.6 weeks for the naltrexone treatment alone. The mean length of time for which patients stayed on naltrexone was 84-103 days with additional psychosocial therapy compared with 43-64 days for the control group. In trials with added pharmacological agents the RRs of stopping treatment were 1.63 at 6 months and 1.31 at 12 months (in favour of naltrexone plus fluoxetine). It became statistically significant at 6 months, but not at 12 months. A meta-analysis of the RR of stopping treatment at week 12 (the minimum follow-up period) was carried out using six of the nine studies. The pooled RR of stopping treatment was 0.81. The results indicated that overall the intervention groups had 19% fewer patients who stopped treatment compared with the control group, but there was only a small number of studies and their quality was relatively poor. No existing economic evaluations were identified. The point estimate for the cost-effectiveness of naltrexone was pound42,500 per quality-adjusted life-year (QALY). Sensitivity analysis was carried out and the incremental cost-effectiveness ratio varied between pound34,600 and pound42,500 per QALY gained. Following successful withdrawal from opioids, naltrexone may be administered on a chronic basis to block any future effects of opioids. Naltrexone appears to have some limited benefit in helping formerly opioid-dependent individuals to remain abstinent, although the quality of the evidence is relatively poor and heterogeneous. The limited quality and extent of the studies precluded an analysis of subgroups likely to benefit from naltrexone prescribing. Oral naltrexone is used infrequently in current UK practice, and this review suggests that this is appropriate as there is little evidence to support its wider implementation. There is an important deficit in information about the quality of life of people who use illicit opioids and this would perhaps be a worthwhile area of research in informing policy questions about the cost-effectiveness of different programmes and interventions.
    Health technology assessment (Winchester, England) 03/2007; 11(6):iii-iv, 1-85. · 4.03 Impact Factor