79 research outputs found
The clinical effectiveness and cost-effectiveness of bariatric (weight loss) surgery for obesity: a systematic review and economic evaluation
No full textObjectives: to assess the clinical effectiveness and cost-effectiveness of bariatric surgery for obesity.Data sources: seventeen electronic databases were searched [MEDLINE; EMBASE; PreMedline In-Process & Other Non-Indexed Citations; The Cochrane Library including the Cochrane Systematic Reviews Database, Cochrane Controlled Trials Register, DARE, NHS EED and HTA databases; Web of Knowledge Science Citation Index (SCI); Web of Knowledge ISI Proceedings; PsycInfo; CRD databases; BIOSIS; and databases listing ongoing clinical trials] from inception to August 2008. Bibliographies of related papers were assessed and experts were contacted to identify additional published and unpublished referencesReview methods: two reviewers independently screened titles and abstracts for eligibility. Inclusion criteria were applied to the full text using a standard form. Interventions investigated were open and laparoscopic bariatric surgical procedures in widespread current use compared with one another and with non-surgical interventions. Population comprised adult patients with body mass index (BMI) ? 30 and young obese people. Main outcomes were at least one of the following after at least 12 months follow-up: measures of weight change; quality of life (QoL); perioperative and postoperative mortality and morbidity; change in obesity-related comorbidities; cost-effectiveness. Studies eligible for inclusion in the systematic review for comparisons of Surgery versus Surgery were RCTs. For comparisons of Surgery versus Non-surgical procedures eligible studies were RCTs, controlled clinical trials and prospective cohort studies (with a control cohort). Studies eligible for inclusion in the systematic review of cost-effectiveness were full cost-effectiveness analyses, cost-utility analyses, cost-benefit analyses and cost-consequence analyses. One reviewer performed data extraction, which was checked by two reviewers independently. Two reviewers independently applied quality assessment criteria and differences in opinion were resolved at each stage. Studies were synthesised through a narrative review with full tabulation of the results of all included studies. In the economic model the analysis was developed for three patient populations, those with BMI ? 40; BMI ? 30 and < 40 with Type 2 diabetes at baseline; and BMI ? 30 and <35. Models were applied with assumptions on costs and comorbidity.Results: a total of 5386 references were identified of which 26 were included in the clinical effectiveness review: three randomised controlled trials (RCTs) and three cohort studies compared surgery with non-surgical interventions and 20 RCTs compared different surgical procedures. Bariatric surgery was a more effective intervention for weight loss than non-surgical options. In one large cohort study weight loss was still apparent 10 years after surgery, whereas patients receiving conventional treatment had gained weight. Some measures of QoL improved after surgery, but not others. After surgery statistically fewer people had metabolic syndrome and there was higher remission of Type 2 diabetes than in non-surgical groups. In one large cohort study the incidence of three out of six comorbidities assessed 10 years after surgery was significantly reduced compared with conventional therapy. Gastric bypass (GBP) was more effective for weight loss than vertical banded gastroplasty (VBG) and adjustable gastric banding (AGB). Laparoscopic isolated sleeve gastrectomy (LISG) was more effective than AGB in one study. GBP and banded GBP led to similar weight loss and results for GBP versus LISG and VBG versus AGB were equivocal. All comparisons of open versus laparoscopic surgeries found similar weight losses in each group. Comorbidities after surgery improved in all groups, but with no significant differences between different surgical interventions. Adverse event reporting varied; mortality ranged from none to 10%. Adverse events from conventional therapy included intolerance to medication, acute cholecystitis and gastrointestinal problems. Major adverse events following surgery, some necessitating reoperation, included anastomosis leakage, pneumonia, pulmonary embolism, band slippage and band erosion. Bariatric surgery was cost-effective in comparison to non-surgical treatment in the reviewed published estimates of cost-effectiveness. However, these estimates are likely to be unreliable and not generalisable because of methodological shortcomings and the modelling assumptions made. Therefore a new economic model was developed. Surgical management was more costly than non-surgical management in each of the three patient populations analysed, but gave improved outcomes. For morbid obesity, incremental cost-effectiveness ratios (ICERs) (base case) ranged between £2000 and £4000 per QALY gained. They remained within the range regarded as cost-effective from an NHS decision-making perspective when assumptions for deterministic sensitivity analysis were changed. For BMI ? 30 and < 40, ICERs were £18,930 at two years and £1397 at 20 years, and for BMI ? 30 and <35, ICERs were £60,754 at two years and £12,763 at 20 years. Deterministic and probabilistic sensitivity analyses produced ICERs which were generally within the range considered cost-effective, particularly at the long twenty year time horizons, although for the BMI 30-35 group some ICERs were above the acceptable range.Conclusions: bariatric surgery appears to be a clinically effective and cost-effective intervention for moderately to severely obese people compared with non-surgical interventions. Uncertainties remain and further research is required to provide detailed data on patient QoL; impact of surgeon experience on outcome; late complications leading to reoperation; duration of comorbidity remission; resource use. Good-quality RCTs will provide evidence on bariatric surgery for young people and for adults with class I or class II obesity. New research must report on the resolution and/or development of comorbidities such as Type 2 diabetes and hypertension so that the potential benefits of early intervention can be assessed
The clinical effectiveness and cost-effectiveness of treatments for children with idiopathic steroid-resistant nephrotic syndrome: a systematic review
No full textThe clinical effectiveness literature on treatments for idiopathic SRNS in children is very limited. The available evidence suggests a beneficial effect of ciclosporin on remission rates and of cyclophosphamide on time to remission; however, the strength of the conclusions drawn is limited by the poor quality of the included studies. The other treatments included in this review were each evaluated by only one study, and none found a statistically significant effect. There is insufficient evidence to determine whether or not there is a clinically significant difference. The available data on costs and outcomes are sparse and do not permit the reliable modelling of the cost-effectiveness of treatments for SRNS at present. A modelling framework is suggested, should more relevant data become available. A well-designed adequately powered randomised controlled trial comparing ciclosporin with other treatments in children with SRNS without genetic mutation is require
Surgery for weight loss in adults
No full textBackground: bariatric (weight loss) surgery for obesity is considered when other treatments have failed. The effects of the available bariatric procedures compared with medical management and with each other are uncertain. This is an update of a Cochrane review first published in 2003 and most recently updated in 2009.Objectives: to assess the effects of bariatric surgery for overweight and obesity, including the control of comorbidities.Search methods: studies were obtained from searches of numerous databases, supplemented with searches of reference lists and consultation with experts in obesity research. Date of last search was November 2013.Selection criteria: randomised controlled trials (RCTs) comparing surgical interventions with non-surgical management of obesity or overweight or comparing different surgical procedures.Data collection and analysis: data were extracted by one review author and checked by a second review author. Two review authors independently assessed risk of bias and evaluated overall study quality utilising the GRADE instrument.Main results: twenty-two trials with 1798 participants were included; sample sizes ranged from 15 to 250. Most studies followed participants for 12, 24 or 36 months; the longest follow-up was 10 years. The risk of bias across all domains of most trials was uncertain; just one was judged to have adequate allocation concealment.All seven RCTs comparing surgery with non-surgical interventions found benefits of surgery on measures of weight change at one to two years follow-up. Improvements for some aspects of health-related quality of life (QoL) (two RCTs) and diabetes (five RCTs) were also found. The overall quality of the evidence was moderate. Five studies reported data on mortality, no deaths occurred. Serious adverse events (SAEs) were reported in four studies and ranged from 0% to 37% in the surgery groups and 0% to 25% in the no surgery groups. Between 2% and 13% of participants required reoperations in the five studies that reported these data.Three RCTs found that laparoscopic Roux-en-Y gastric bypass (L)(RYGB) achieved significantly greater weight loss and body mass index (BMI) reduction up to five years after surgery compared with laparoscopic adjustable gastric banding (LAGB). Mean end-of-study BMI was lower following LRYGB compared with LAGB: mean difference (MD) -5.2 kg/m² (95% confidence interval (CI) -6.4 to -4.0; P < 0.00001; 265 participants; 3 trials; moderate quality evidence). Evidence for QoL and comorbidities was very low quality. The LRGYB procedure resulted in greater duration of hospitalisation in two RCTs (4/3.1 versus 2/1.5 days) and a greater number of late major complications (26.1% versus 11.6%) in one RCT. In one RCT the LAGB required high rates of reoperation for band removal (9 patients, 40.9%).Open RYGB, LRYGB and laparoscopic sleeve gastrectomy (LSG) led to losses of weight and/or BMI but there was no consistent picture as to which procedure was better or worse in the seven included trials. MD was -0.2 kg/m² (95% CI -1.8 to 1.3); 353 participants; 6 trials; low quality evidence) in favour of LRYGB. No statistically significant differences in QoL were found (one RCT). Six RCTs reported mortality; one death occurred following LRYGB. SAEs were reported by one RCT and were higher in the LRYGB group (4.5%) than the LSG group (0.9%). Reoperations ranged from 6.7% to 24% in the LRYGB group and 3.3% to 34% in the LSG group. Effects on comorbidities, complications and additional surgical procedures were neutral, except gastro-oesophageal reflux disease improved following LRYGB (one RCT). One RCT of people with a BMI 25 to 35 and type 2 diabetes found laparoscopic mini-gastric bypass resulted in greater weight loss and improvement of diabetes compared with LSG, and had similar levels of complications.Two RCTs found that biliopancreatic diversion with duodenal switch (BDDS) resulted in greater weight loss than RYGB in morbidly obese patients. End-of-study mean BMI loss was greater following BDDS: MD -7.3 kg/m² (95% CI -9.3 to -5.4); P < 0.00001; 107 participants; 2 trials; moderate quality evidence). QoL was similar on most domains. In one study between 82% to 100% of participants with diabetes had a HbA1c of less than 5% three years after surgery. Reoperations were higher in the BDDS group (16.1% to 27.6%) than the LRYGB group (4.3% to 8.3%). One death occurred in the BDDS group.One RCT comparing laparoscopic duodenojejunal bypass with sleeve gastrectomy versus LRYGB found BMI, excess weight loss, and rates of remission of diabetes and hypertension were similar at 12 months follow-up (very low quality evidence). QoL, SAEs and reoperation rates were not reported. No deaths occurred in either group.One RCT comparing laparoscopic isolated sleeve gastrectomy (LISG) versus LAGB found greater improvement in weight-loss outcomes following LISG at three years follow-up (very low quality evidence). QoL, mortality and SAEs were not reported. Reoperations occurred in 20% of the LAGB group and in 10% of the LISG group.One RCT (unpublished) comparing laparoscopic gastric imbrication with LSG found no statistically significant difference in weight loss between groups (very low quality evidence). QoL and comorbidities were not reported. No deaths occurred. Two participants in the gastric imbrication group required reoperation.Authors' conclusions: surgery results in greater improvement in weight loss outcomes and weight associated comorbidities compared with non-surgical interventions, regardless of the type of procedures used. When compared with each other, certain procedures resulted in greater weight loss and improvements in comorbidities than others. Outcomes were similar between RYGB and sleeve gastrectomy, and both of these procedures had better outcomes than adjustable gastric banding. For people with very high BMI, biliopancreatic diversion with duodenal switch resulted in greater weight loss than RYGB. Duodenojejunal bypass with sleeve gastrectomy and laparoscopic RYGB had similar outcomes, however this is based on one small trial. Isolated sleeve gastrectomy led to better weight-loss outcomes than adjustable gastric banding after three years follow-up. This was based on one trial only. Weight-related outcomes were similar between laparoscopic gastric imbrication and laparoscopic sleeve gastrectomy in one trial. Across all studies adverse event rates and reoperation rates were generally poorly reported. Most trials followed participants for only one or two years, therefore the long-term effects of surgery remain unclear
Bone-anchored hearing aids for people with bilateral hearing impairment: a systematic review
No full textBACKGROUND: Bone-anchored hearing aids (BAHAs) are indicated for people with conductive or mixed hearing loss who can benefit from amplification of sound. In resource limited health care systems, it is important that evidence regarding the benefit of BAHAs is critically appraised to aid decision-making.OBJECTIVE OF REVIEW: To assess the clinical effectiveness of BAHAs for people with bilateral hearing impairment.TYPE OF REVIEW: Systematic review.SEARCH STRATEGY: Nineteen electronic resources were searched from inception to November 2009. Additional studies were sought from reference lists, clinical experts and BAHA manufacturers.EVALUATION METHOD: Inclusion criteria were applied by two reviewers independently. Data extraction and quality assessment of full papers were undertaken by one reviewer and checked by a second. Studies were synthesised through narrative review with tabulation of results.RESULTS: Twelve studies were included. Studies suggested audiological benefits of BAHAs when compared with bone-conduction hearing aids or no aiding. A mixed pattern of results was seen when BAHAs were compared to air-conduction hearing aids. Improvements in quality of life with BAHAs were found by a hearing-specific instrument but not generic quality of life measures. Issues such as improvement of discharging ears and length of time the aid can be worn were not adequately addressed by the studies. Studies demonstrated some benefits of bilateral BAHAs. Adverse events data were limited. The quality of the studies was low.CONCLUSIONS: The available evidence is weak. As such, caution is indicated in the interpretation of presently available data. However, based on the available evidence, BAHAs appear to be a reasonable treatment option for people with bilateral conductive or mixed hearing loss. Further research into the benefits of BAHAs, including quality of life, is required to reduce the uncertainty.<br/
Michael Wells serves as a guest author for TortsProf Blog
No full textColquitt Carter Chair in Tort and Insurance Law Michael L. Wells authored Constitutional Torts and Tort Theory as a guest on the TortsProf Blog
Dasatinib, high dose imatinib and nilotinib for the treatment of imatinib-resistant chronic myeloid leukaemia: a systematic review and economic evaluation
No full textTreatments for patients with CML have included hydroxycarbamide, interferon alfa, stem cell transplantation and acute leukaemia-style chemotherapy. More recently, tyrosine-kinase inhibitor drugs have been developed. Imatinib was the first tyrosine-kinase inhibitor to be used for treating CML. It is considered to be effective and is recommended by NICE for the treatment of CML in the first line.1 Subsequently, dasatinib and nilotinib, also tyrosine-kinase inhibitors, have been developed and are being used for the treatment of CML.Guidance on second-line treatment for those patients developing resistance to imatinib is less clear. In clinical practice, imatinib at high doses is frequently used. Dasatinib and nilotinib may also be treatment options. However, there have been no evaluations of the clinical and cost effectiveness of these treatments compared to each other or to most of the older treatment options for patients with imatinib-resistant CML. Economic evaluations of dasatinib and nilotinib compared to interferon alfa with cytarabine have been conducted (appendix 8 of CML assessment report2).The function of this review is therefore to assess the clinical and cost effectiveness of high dose imatinib, dasatinib and nilotinib compared to each other or traditional technologies such as hydroxycarbamide, interferon alfa, stem cell transplantation and acute chemotherapy for the treatment of patients with imatinib-resistant CML. This report is a part update of a previous report undertaken to inform the NICE MTA of dasatinib and nilotinib for people with imatinib resistant and imatinib intolerant CML,2 where the current report focuses on those with imatinib resistant disease only.The HTA Programme commisioned this technology assessment report on behalf of the National Institute for Health and Clinical Excellence
Return of the American: speculations on Fred Gipson and Texas writing
No full textTo the extent that the Southwest perceives itself as an alter ego of mainstream America, the myth that informs Fred Gipson's writing should not be interpreted as nostalgia, but rather as an attempt by a community of believers to survive in the shadow of a dominant culture. The structures that undergird Gipson's fiction and history and the relationships of works, author, and audience reveal a hierarchy of values and a social construction of reality communicated through compelling metaphors and symbols. If the fiction seems formulaic and the history taxonomic, that is in part because in the Southwest a distinction has never been clearly drawn between fiction and history: both suffer from an aesthetic of verisimilitude. Criticism has been arrested by these symptoms. The intentionality of this writing has not been coherently examined, nor has the world view that manifests itself in this literature been exposed. Products of a residual, intuitive America where assimilation has been slow, the fiction and the history of the region are neither escapist nor reversionary, but project an America that was, and might have been. This literature is characteristic of the fiction and history that emerging nations produce: mythopoetic, vernacular in setting and form, and affective
Recommended from our members
Mersenne numbers
No full textThese notes have been issued on a small scale in 1983 and 1987 and on request at other times. This issue follows two items of news. First, WaIter Colquitt and Luther Welsh found the 'missed' Mersenne prime M110503 and advanced the frontier of complete Mp-testing to 139,267. In so doing, they terminated Slowinski's significant string of four consecutive Mersenne primes. Secondly, a team of five established a non-Mersenne number as the largest known prime. This result terminated the 1952-89 reign of Mersenne primes. All the original Mersenne numbers with p < 258 were factorised some time ago. The Sandia Laboratories team of Davis, Holdridge & Simmons with some little assistance from a CRAY machine cracked M211 in 1983 and M251 in 1984. They contributed their results to the 'Cunningham Project', care of Sam Wagstaff. That project is now moving apace thanks to developments in technology, factorisation and primality testing. New levels of computer power and new computer architectures motivated by the open-ended promise of parallelism are now available. Once again, the suppliers may be offering free buildings with the computer. However, the Sandia '84 CRAY-l implementation of the quadratic-sieve method is now outpowered by the number-field sieve technique. This is deployed on either purpose-built hardware or large syndicates, even distributed world-wide, of collaborating standard processors. New factorisation techniques of both special and general applicability have been defined and deployed. The elliptic-curve method finds large factors with helpful properties while the number-field sieve approach is breaking down composites with over one hundred digits. The material is updated on an occasional basis to follow the latest developments in primality-testing large Mp and factorising smaller Mp; all dates derive from the published literature or referenced private communications. Minor corrections, additions and changes merely advance the issue number after the decimal point. The reader is invited to report any errors
and omissions that have escaped the proof-reading, to answer the unresolved questions noted and to suggest additional material associated with this subject
Bone-anchored hearing aids for people who are bilaterally deaf: a systematic review and economic evaluation
No full textThe aim of this systematic review, using standard methodology,was to assess the clinical and cost-effectiveness of bone-anchored hearing aids (BAHAs) for people who are bilaterally deaf. Prospective studies comparing BAHAs versus conventional hearing aids [air conduction hearing aid (ACHA) or bone conduction hearing aid (BCHA)], unaided hearing or ear surgery; and unilateral versus bilateral BAHAs were eligible. Twelve clinical effectiveness studies were included. No eligible comparisons with ear surgery were identified. Overall quality was rated as weak for all included studies.There appeared to be some audiological benefits of BAHAs compared with BCHAs and improvements in speech understanding in noise compared with ACHAs, however ACHAs may produce better audiological results for other outcomes; the limited evidence reduces certainty. Hearing is improved with BAHAs compared with unaided hearing. Improvements in QoL with BAHAs were identified by a hearing-specific instrument but not generic QoL measures. Studies comparing unilateral with bilateral BAHAs suggested benefits of bilateral BAHAs in many, but not all, situations.A decision analytic model was developed to estimate the costs and benefits of unilateral BAHAs over a ten year time horizon. The incremental cost per user receiving BAHA, compared with BCHA, was £16,344 for children and £13,281 for adults. In an exploratory analysis the incremental cost per QALY gained was between £118,898 and £55,424 for children and between £98,790 to £46,051 for adults for BAHAs compared with BCHA, depending on the assumed QoL gain and proportion of each modelled cohort using their hearing aid for eight or more hours per day. Deterministic sensitivity analysis suggested results were highly sensitive to the assumed proportion of people using BCHA for eight or more hours per day.Exploratory cost effectiveness analysis suggests that BAHAs are unlikely to be a cost effective option where the benefi ts are similar for BAHAs and their comparators. The greater the benefit from aided hearing and the greater the difference in the proportion of people using the hearing aid for eight hours or more per day, the more likely BAHAs are to be a cost effective option. The inclusion of other dimensions of QoL may also increase the likelihood of BAHAs being a cost effective option.A national audit of BAHAs is needed to provide clarity on the many areas of uncertainty surrounding BAHAs
Mathematical modelling of the dynamic response of metamaterial structures
No full textThis thesis constitutes an exposition of the work carried out by the author whilst examining several physical problems under the broad theme of the dynamic response of metamaterial structures.
An outline of the thesis is provided in chapter one.
Chapter two introduces some notation and preliminary results on general lattice equations.
Chapter three examines the dispersive behaviour of non-classical discrete elastic lattice systems.
In particular, the effect of distributing the inertial properties of the lattice over the elastic rods, in addition to at the junctions, is considered.
It is demonstrated that the effective material properties in the long wavelength limit are not what one would expect from the static response of the lattice.
The effect of various interactions on the dispersive properties of the triangular cell lattice is considered, including so-called truss, frame, and micro-polar interactions.
Compact analytical estimates for the band widths are presented, allowing the design of metamaterial structures possessing pass and/or stop bands at specific frequencies and in specified directions.
The finite frequency response of several lattice structures is considered in chapter four.
In particular, the dynamic anisotropy of both scalar and elastic lattices is examined.
The resulting strongly anisotropic material response is linked, explicitly, to the dispersive properties of the lattice.
A novel application of dynamic anisotropy to the focusing, shielding, and negative refraction of elastic waves using a flat discrete "metamaterial lens'' is presented.
Chapter five is devoted to the analysis, using the dynamic Green's function, of a finite rectilinear inclusion in an infinite square lattice.
Several representations of the Green's function are presented, including expression in terms of hypergeometric functions, which are employed in deriving band edge expansions.
It is shown that localised defect modes, characterised by displacements which decay rapidly away from the defect, can be initiated by reducing the mass of one or more lattice nodes, whilst ensuring that the mass of the nodes remains positive.
For one- and three-dimensional multi-atomic lattices, there exists a bound on the contrast in mass between the defect and ambient lattice such that localised defect modes exist.
However, it is shown that for the two-dimensional lattice, no such bound exists, provided that the masses remain positive.
The analysis of a finite-sized defect region is accompanied by the waveguide modes that may exist in a lattice containing an infinite chain of point defects.
A numerical simulation illustrates that the solution of the problem for an infinite chain can be used to predict the range of eigenfrequencies of localised modes for a finite but, sufficiently long, array of masses representing a rectilinear defect in a square lattice.
Continuing with the theme of defects, chapter six examines response of a triangular thermoelastic lattice, with an edge crack under mode I loading.
The response of the triangular lattice is compared with that of the corresponding continuum.
The model is related to the phenomenon of thermal striping, which occurs when a structure is exposed to periodic variations in temperature.
In the thermal striping regime, crack propagation is a fatiguing processes with the rate of crack growth being proportional to some power of the peak-to-peak amplitude of the stress intensity factor.
An "effective stress intensity factor'' for the lattice is introduced and it is demonstrated that, in the homogenised limit, the "effective stress intensity factor'' is lower than the stress intensity factor of the continuum for sufficiently long cracks and low frequencies.
Finally, chapter seven presents a detailed analysis of a non-singular square cloak for acoustic, out-of-plane shear elastic, and electromagnetic waves.
The propagation of waves through the cloak is examined analytically and is complemented with a range of numerical illustrations.
The efficacy of the regularised cloak is demonstrated and an objective numerical measure of the quality of the cloaking effect is introduced.
The results presented show that the cloaking effect persists over a sufficiently wide range of frequencies.
To illustrate further the effectiveness of the regularised cloak, a Young's double slit experiment is presented.
The stability of the interference pattern is examined when a cloaked and uncloaked obstacle are successively placed in front of one of the apertures.
A significant advantage of this particular regularised square cloak is the straightforward connection with a discrete lattice.
It is shown that an approximate cloak can be constructed using a discrete lattice structure.
The efficiency of such a lattice cloak is analysed and several illustrative simulations are presented.
It is demonstrated that effective cloaking can be achieved by using a relatively simple lattice, particularly in the low frequency regime.
This discrete lattice structure provides a possible avenue toward the physical realisation of invisibility cloaks
- …
