Strength of public preferences for endovascular or open aortic aneurysm repair.

BACKGROUND: This study evaluated public preferences for the treatment processes for abdominal aortic aneurysm repair in order to allow them to be incorporated into a cost-effectiveness analysis. METHODS: This was a telephone survey using a trade-off method in UK resident adults (aged at least 18 years) with no previous diagnosis of a vascular condition. RESULTS: Some 167 of 209 participants (79·9 per cent) stated that they would prefer endovascular aneurysm repair (EVAR), 40 (19·1 per cent) preferred open surgery and two (1·0 per cent) stated no preference. Participants preferred EVAR because of the less invasive nature of the intervention and quicker recovery. Participants preferring open surgery cited reasons such as having a single follow-up appointment, and a procedure that felt more permanent. When participants were asked to make a sacrifice in order to have their preferred treatment, 122 (58·4 per cent) favoured EVAR, 18 (8·6 per cent) favoured open surgery and 69 (33·0 per cent) had no preference. Those preferring EVAR were willing to give up a mean of 0·135 expected quality-adjusted life-years (QALYs) to have EVAR, compared with a willingness to give up 0·033 expected QALYs among those preferring open repair. CONCLUSION: These results indicate a clear preference for EVAR over open surgery for aortic aneurysm.

ANTECEDENTES: Este estudio evaluó las preferencias de la opinion pública en relación a las opciones de tratamiento para la reparación del aneurisma de aorta abdominal, con el objetivo de que dichas preferencias se puedan incorporar en un análisis de coste-efectividad. MÉTODOS: Se realizó una encuesta telefónica utilizando el método trade-off (solución de intercambio) en adultos residentes en el Reino Unido (mayores de 18 años) sin diagnóstico previo de enfermedad vascular. RESULTADOS: Un total de 167 (79,9%) de 209 participantes declararon que preferirían la reparación endovascular del aneurisma (endovascular aneurysm repair, EVAR), 40 (19,1%) prefirieron cirugía abierta y dos (1,0%) no tenían preferencia. Los participantes prefirieron el EVAR debido a la naturaleza menos invasiva de la intervención y a tiempos de recuperación más rápidos. Los participantes que preferían la cirugía abierta mencionaron como razones tener una única visita de seguimiento y consideraron que se trataba de un procedimiento más permanente. Cuando se pidió a los participantes que para recibir su tratamiento preferido hicieran un intercambio, 122 (58,4%) se decantaron por la EVAR, 18 (8,6%) por la cirugía abierta y 69 (33%) no tuvieron preferencia. Los que prefirieron EVAR estaban dispuestos a renunciar a una media de 0,135 años de vida ajustados por calidad (QALYs) esperados con tal de recibir una EVAR en comparación con la renuncia de 0,033 QALYs esperada entre quienes preferían la reparación abierta. CONCLUSIÓN: Estos resultados indican una clara preferencia por la EVAR sobre la cirugía abierta, lo que está en desacuerdo con la reciente recomendación de NICE de que la EVAR no debe recomendarse como una opción de tratamiento. Los hallazgos sugieren que se debe prestar mayor atención a las características del proceso de tratamiento. Al no incorporar explícitamente tales preferencias en el proceso de toma de decisiones, NICE corre el riesgo de recomendar opciones de tratamiento que son contrarias a las preferencias de la población del Reino Unido.

Systematic review of carotid artery procedures and the volume-outcome relationship in Europe.

BACKGROUND: Hospitals that conduct more procedures on the carotid arteries may achieve better outcomes. In the context of ongoing reconfiguration of UK vascular services, this systematic review was conducted to evaluate the relationship between the volume of carotid procedures and outcomes, including mortality and stroke. METHODS: Searches of electronic databases identified studies that reported the effect of hospital or clinician volume on outcomes. Reference and citation searches were also performed. Inclusion was restricted to European populations on the basis that the model of healthcare delivery is similar across Europe, but differs from that in the USA and elsewhere. Analyses of hospital and clinician volume, and carotid endarterectomy (CEA) and carotid artery stenting (CAS) were conducted separately. RESULTS: Eleven eligible studies were identified (233 411 participants), five from the UK, two from Sweden, one each from Germany, Finland and Italy, and a combined German, Austrian and Swiss population. All studies were observational. Two large studies (179 736 patients) suggested an inverse relationship between hospital volume and mortality (number needed to treat (NNT) as low as 165), and combined mortality and stroke (NNT as low as 93), following CEA. The evidence was less clear for CAS; multiple analyses in three studies did not identify convincing evidence of an association. Limited data are available on the relationship between clinician volume and outcome in CAS; in CEA, an inverse relationship was identified by two of three small studies. CONCLUSION: The evidence from the largest and highest-quality studies included in this review support the centralization of CEA.

Procedure Volume and the Association with Short-term Mortality Following Abdominal Aortic Aneurysm Repair in European Populations: A Systematic Review.

OBJECTIVE: To evaluate the relationship between the volume of abdominal aortic aneurysm (AAA) procedures undertaken and the primary outcome of mortality in Europe. Previous systematic reviews of this relationship are outdated and are overwhelmingly based on US data. DATA SOURCES: Comprehensive searching within MEDLINE and other bibliographic databases supplemented by citation searching and hand-searching of journals was undertaken to identify studies that reported the effect of hospital or clinician volume on any reported outcomes in adult, European populations, undergoing AAA repair and published in the last 10 years. METHODS: Two reviewers conducted study selection with independent, duplicate data extraction and quality assessment. A planned meta-analysis was not conducted because of the high risk of bias, the likelihood of individual study subjects being included in more than one study and diversity in the clinical populations studied and methods used. RESULTS: Sixteen studies (n = 237,074 participants) from the UK (n = 11 studies), Germany (n = 3 studies), Norway (n = 1 study), and one from the UK and Sweden were included. Data in the included studies came from administrative databases and clinical registries incorporating a variety of clinical and procedural groups; the study quality was limited by the use of observational study designs. Overall, the evidence favoured the existence of an inverse volume outcome relationship between hospital volume and mortality. Insufficient evidence was available to reach conclusions on the relationship between clinician volume and outcome and between hospital or clinician volume and secondary outcomes including complications and length of hospital stay. CONCLUSIONS: The evidence from this review suggests a relationship between the hospital volume of AAA procedures conducted and short-term mortality; however, as volume typically represents a complex amalgamation of factors further research will be useful to identify the core characteristics of volume that influence improved outcomes.

Weighting and valuing quality-adjusted life-years using stated preference methods: preliminary results from the Social Value of a QALY Project.

OBJECTIVES: To identify characteristics of beneficiaries of health care over which relative weights should be derived and to estimate relative weights to be attached to health gains according to characteristics of recipients of these gains (relativities study); and to assess the feasibility of estimating a willingness-to-pay (WTP)-based value of a quality-adjusted life-year (QALY) (valuation study). DESIGN: Two interview-based surveys were administered - one (for the relativities study) to a nationally representative sample of the population in England and the other (for the valuation study) to a smaller convenience sample. SETTING: The two surveys were administered by the National Centre for Social Research (NatCen) in respondents' homes. PARTICIPANTS: 587 members of the public were interviewed for the relativities study and 409 for the valuation study. METHODS: In the relativities study, in-depth qualitative work and considerations of policy relevance resulted in the identification of age and severity of illness as relevant characteristics. Scenarios reflecting these, along with additional components reflecting gains in QALYs, were presented to respondents in a series of pairwise choices using two types of question: discrete choice and matching. These questions were part of a longer questionnaire (including attitudinal and sociodemographic questions), which was administered face to face using a computer-assisted personal interview. In the valuation study, respondents were asked about their WTP to avoid/prevent different durations of headache or stomach illness and to value these states on a scale (death = 0; full health = 1) using standard gamble (SG) questions. RESULTS: Discrete choice results showed that age and severity variables did not have a strong impact on respondents' choices over and above the health (QALY) gains presented. In contrast, matching showed age and severity impacts to be strong: depending on method of aggregation, gains to some groups were weighted three to four times more highly than gains to others. Results from the WTP and SG questions were combined in different ways to arrive at values of a QALY. These vary from values which are in the vicinity of the current National Institute for Health and Clinical Excellence (NICE) threshold to extremely high values. CONCLUSIONS: With respect to relative weights, more research is required to explore methodological differences with respect to age and severity weighting. On valuation, there are particular issues concerning the extent to which 'noise' and 'error' in people's responses might generate extreme and unreliable figures. Methods of aggregation and measures of central tendency were issues in both weighting and valuation procedures and require further exploration.

BoTULS: a multicentre randomised controlled trial to evaluate the clinical effectiveness and cost-effectiveness of treating upper limb spasticity due to stroke with botulinum toxin type A.

OBJECTIVE: To compare the clinical effectiveness and cost-effectiveness of treating upper limb spasticity due to stroke with botulinum toxin type A plus an upper limb therapy programme with the upper limb therapy programme alone. DESIGN: A multicentre open-label parallel-group randomised controlled trial and economic evaluation. SETTING: Twelve stroke services in the north of England, UK. PARTICIPANTS: Three hundred and thirty-three adults with upper limb spasticity at the shoulder, elbow, wrist or hand and reduced upper limb function due to stroke more than 1 month previously. INTERVENTIONS: The intervention group received botulinum toxin type A injection(s) plus a 4-week programme of upper limb therapy. The control group received the upper limb therapy programme alone. Participants were clinically reassessed at 3, 6 and 9 months to determine the need for repeat botulinum toxin type A injection(s) and/or therapy. MAIN OUTCOME MEASURES: The primary outcome was upper limb function 1 month after study entry measured by the Action Research Arm Test (ARAT). A successful outcome was defined as: (1) a change of three or more points on the ARAT scale for a participant whose baseline ARAT score was between 0 and 3, (2) a change of six or more points on the ARAT scale for a participant whose baseline ARAT score was between 4 and 51, or (3) a final ARAT score of 57 for a participant whose baseline ARAT score was 52-56. Outcome assessments were undertaken at 1, 3 and 12 months by an assessor who was blinded to the study group allocation. Upper limb impairment and activity limitation were assessed by: Modified Ashworth Scale; Motricity Index; grip strength; ARAT; Nine-Hole Peg Test; upper limb basic functional activity questions and the Barthel Activities of Daily Living (ADL) Index. Stroke-related quality of life/participation restriction was measured using the Stroke Impact Scale, European Quality of Life-5 Dimensions (EQ-5D) and the Oxford Handicap Scale. Upper limb pain was assessed using numerical rating scales. Participant-selected upper limb goal achievement (1 month only) was measured using the Canadian Occupational Performance Measure. Adverse events were compared. Health-care and social services resource use was compared during the first 3 months postrandomisation. EQ-5D data were used to calculate the quality-adjusted life-years (QALYs) associated with intervention and control treatments, and the incremental cost per QALY gained of botulinum toxin type A plus therapy compared with therapy alone was estimated. The sensitivity of the base-case results to alternative assumptions was investigated, and cost-effectiveness acceptability curves, which summarise the evidence of botulinum toxin type A plus therapy being cost-effective for a range of societal willingness to pay for a QALY values, are presented. RESULTS: Randomisation groups were well matched at baseline. There was no significant difference between the groups for the primary outcome of improved arm function at 1 month. This was achieved by 30/154 (19.5%) in the control group and 42/167 (25.1%) in the intervention group (p = 0.232). The relative risk of having a 'successful treatment' in the intervention group compared with the control group was 1.3 [95% confidence interval (CI) 0.9 to 2.0]. No significant differences in improved arm function were seen at 3 or 12 months. In terms of secondary outcomes, muscle tone/spasticity at the elbow was decreased in the intervention group compared with the control group at 1 month. The median change in the Modified Ashworth Scale was - 1 in the intervention group compared with zero in the control group (p < 0.001). No difference in spasticity was seen at 3 or 12 months. Participants treated with botulinum toxin type A showed improvement in upper limb muscle strength at 3 months. The mean change in strength from baseline (upper limb component of the Motricity Index) was 3.5 (95% CI 0.1 to 6.8) points greater in the intervention group compared with the control group. No differences were seen at 1 or 12 months. Participants in the intervention group were more likely to be able to undertake specific basic functional activities, e.g. dress a sleeve, clean the palm and open the hand for cutting fingernails. At 1 month, 109/144 (75.7%) of the intervention group and 79/125 (63.2%) of the control group had improved by at least one point on a five-point Likert scale for at least one of these tasks (p = 0.033). At 3 months the corresponding proportions were 102/142 (71.8%) of the intervention group and 71/122 (58.2%) of the control group (p = 0.027). Improvement was sustained at 12 months for opening the hand for cleaning the palm and opening the hand for cutting the nails but not for other activities. Pain rating improved by two points on a 10-point severity rating scale in the intervention group compared with zero points in the control group (p = 0.004) at 12 months, but no significant differences were seen at 1 or 3 months. There were a number of occasions when there were statistically significant differences in favour of the intervention group; however, these differences were small and of uncertain clinical relevance. These differences were: 3 months - upper limb function (change in ARAT score from baseline), pain (EQ-5D) and participation restriction (Oxford Handicap Scale); 12 months - anxiety/depression (EQ-5D) and participation restriction (Oxford Handicap Scale). No differences in grip strength, dexterity or the Barthel ADL Index were found at any time point. There were no differences between the groups for achievement of patient-selected goals. There was a higher incidence of general malaise/flu-like/cold symptoms in participants treated with botulinum toxin type A with a relative risk of 7.6 (95% CI 1.8 to 32.3). Only one serious adverse event (dysphagia) was potentially related to botulinum toxin type A. Time since stroke and severity of initial upper limb function were preplanned subgroup analyses. There was no significant difference in either subgroup for achievement of ARAT 'success' following treatment with botulinum toxin type A. The base-case incremental cost-effectiveness ratio was 93,500 pounds per QALY gained and estimation of the cost-effectiveness acceptability curve for botulinum toxin type A plus the upper limb therapy programme indicated that there was only a 0.36 probability of it being cost-effective at a threshold ceiling ratio of 20,000 pounds per QALY. CONCLUSIONS: The addition of botulinum toxin type A to an upper limb therapy programme to treat spasticity due to stroke did not enhance improvement in upper limb function when assessed by the prespecified primary outcome measure at 1 month. However, improvements were seen in muscle tone at 1 month, upper limb strength at 3 months, upper limb functional activities related to undertaking specific basic functional tasks at 1, 3 and 12 months, and upper limb pain at 12 months. Botulinum toxin was well tolerated and side effects were minor. The addition of botulinum toxin type A to an upper limb therapy programme for the treatment of upper limb spasticity due to stroke was not estimated to be cost-effective at levels of willingness to pay for a QALY set by NHS decision-makers. TRIAL REGISTRATION: ISRCTN78533119; EudraCT 2004-002427-40; CTA 17136/0230/001.

A prospective randomised controlled trial and economic modelling of antimicrobial silver dressings versus non-adherent control dressings for venous leg ulcers: the VULCAN trial.

OBJECTIVE: To examine the effectiveness and cost-effectiveness of antimicrobial silver-donating dressings for venous leg ulcers compared with simple non-adherent (also known as low-adherent) dressings. DESIGN: A pragmatic, prospective randomised controlled trial (RCT) and cost-effectiveness analysis of silver-donating versus low-adherent dressings in the treatment of venous leg ulcers. A non-randomised observational group was also recruited. SETTING: Primary and secondary care services in the north and south of England (Sheffield and Exeter). PARTICIPANTS: Consenting patients with active ulceration of the lower leg that had been present for a period of greater than 6 weeks. INTERVENTIONS: Patients were randomised to receive either a silver-donating or non-silver low-adherent dressing applied beneath compression bandages or hosiery. The choice of dressing within these groups was left to clinician preference. Evaluation was by clinical assessment, supplemented by evaluation of quality of life and cost-effectiveness. MAIN OUTCOME MEASURES: The primary outcome measure was complete ulcer healing at 12 weeks in the index limb. Secondary measures were costs and quality-adjusted life-years (QALYs), cost-effectiveness, time to healing, and recurrence rate at 6 months and 1 year. RESULTS: In total, 304 participants were recruited to the clinical trial: 213 to the RCT and 91 to the observational arm. Within the RCT 107 were randomised to antimicrobial dressings and 106 to the control dressings. There were no significant differences (p > 0.05) between the two groups for the primary outcome measure of proportion of ulcers healed at 12 weeks (59.6% for silver and 56.7% for control dressings). The overall median time to healing was also not significantly different between the two groups (p = 0.408). A total of 24 patients had recurrent ulcers within 1 year; the recurrence rates of 11.6% (n = 11) for the antimicrobial and 14.4% (n = 13) for the control dressings were not significant. Mean utility valuations for both the EuroQol 5 dimensions (EQ-5D) quality of life questionnaire and Short Form 6 dimensions (SF-6D) utility index showed no differences for either group at 1, 3, 6 or 12 months. Compared with the control group, the antimicrobial group had an incremental cost of 97.85 pounds and an incremental QALY gain of 0.0002, giving an incremental cost-effectiveness ratio for the antimicrobial dressings of 489,250 pounds. Cost-effectiveness modelling of the results of the RCT showed that antimicrobial dressings were not cost-effective. CONCLUSIONS: No significant differences in either primary or secondary end points were found between the use of antimicrobial silver-donating dressings and the control group of low-adherent dressings. Modelling showed that antimicrobial silver dressings were not cost-effective. TRIAL REGISTRATION: Current Controlled Trials ISRCTN72485131.

Randomized controlled trial and cost-effectiveness analysis of silver-donating antimicrobial dressings for venous leg ulcers (VULCAN trial).

BACKGROUND: Antimicrobial silver dressings are used beneath graduated compression in the treatment of venous ulceration. There is little information on whether their use is effective. This was a prospective randomized trial and cost-effectiveness analysis of silver-donating versus non-silver low-adherence dressings in the treatment of venous leg ulcers. METHODS: Patients were randomized between the two types of dressing. The primary outcome measure was complete ulcer healing at 12 weeks. Secondary outcomes included time to healing, quality of life and cost-effectiveness. RESULTS: A total of 213 patients were recruited. There was no difference between the dressings in the proportion of ulcers healed at 12 weeks (59.6 per cent for silver and 56.7 per cent for control dressings). Mean utility scores for the EuroQol 5D and Short Form 6D were similar in both groups at 1, 3, 6 and 12 months. Compared with the control group the antimicrobial group had an incremental cost of pounds sterling 97.85 and an incremental quality-adjusted life year gain of 0.0002, giving an incremental cost-effectiveness ratio of pounds sterling 489 250 for the antimicrobial dressings. CONCLUSION: No significant differences were found in either primary or secondary endpoints. There was no evidence to support the routine use of silver-donating dressings beneath compression for venous ulceration. REGISTRATION NUMBER: ISRCTN 72485131 (http://www.controlled-trials.com).

Evaluation of the cost-effectiveness of root canal treatment using conventional approaches versus replacement with an implant.

AIM: To evaluate the cost-effectiveness of root canal treatment for a maxillary incisor tooth with a pulp infection, in comparison with extraction and replacement with a bridge, denture or implant supported restoration. METHODOLOGY: A Markov model was built to simulate the lifetime path of restorations placed on the maxillary incisor following the initial treatment decision. It was assumed that the goal of treatment was the preservation of a fixed platform support for a crown without involving the adjacent teeth. Consequently, the model estimates the lifetime costs and the total longevity of tooth and implant supported crowns at the maxillary incisor site. The model considers the initial treatment decisions, and the various subsequent treatment decisions that might be taken if initial restorations fail. RESULTS: Root canal treatment extended the life of the tooth at an additional cost of pound5-8 per year of tooth life. Provision of orthograde re-treatment, if the root canal treatment fails returns further extension of the expected life of the tooth at a cost of pound12-15 per year. Surgical re-treatment is not cost-effective; it is cheaper, per year, to extend the life of the crown by replacement with a single implant restoration if orthograde endodontic treatment fails. CONCLUSION: Modelling the available clinical and cost data indicates that, root canal treatment is highly cost-effective as a first line intervention. Orthograde re-treatment is also cost-effective, if a root treatment subsequently fails, but surgical re-treatment is not. Implants may have a role as a third line intervention if re-treatment fails.

A randomised controlled trial examining the longer-term outcomes of standard versus new antiepileptic drugs. The SANAD trial.

OBJECTIVES: To compare clinicians' choice of one of the standard epilepsy drug treatments (carbamazepine or valproate) versus appropriate comparator new drugs. DESIGN: A clinical trial comprising two arms, one comparing new drugs in carbamazepine and the other with valproate. SETTING: A multicentre study recruiting patients with epilepsy from hospital outpatient clinics. PARTICIPANTS: Patients with an adequately documented history of two or more clinically definite unprovoked epileptic seizures within the last year for whom treatment with a single antiepileptic drug represented the best therapeutic option. INTERVENTIONS: Arm A was carbamazepine (CBZ) versus gabapentin (GBP) versus lamotrigine (LTG) versus oxcarbazepine (OXC) versus topiramate (TPM). Arm B valproate (VPS) versus LTG versus TPM. MAIN OUTCOME MEASURES: Time to treatment failure (withdrawal of the randomised drug for reasons of unacceptable adverse events or inadequate seizure control or a combination of the two) and time to achieve a 12-month remission of seizures. Time from randomisation to first seizure, 24-month remission of seizures, incidence of clinically important adverse events, quality of life (QoL) outcomes and health economic outcomes were also considered. RESULTS: Arm A recruited 1721 patients (88% with symptomatic or cryptogenic partial epilepsy and 10% with unclassified epilepsy). Arm B recruited 716 patients (63% with idiopathic generalised epilepsy and 25% with unclassified epilepsy). In Arm A LTG had the lowest incidence of treatment failure and was statistically superior to all drugs for this outcome with the exception of OXC. Some 12% and 8% fewer patients experienced treatment failure on LTG than CBZ, the standard drug, at 1 and 2 years after randomisation, respectively. The superiority of LTG over CBZ was due to its better tolerability but there is satisfactory evidence indicating that LTG is not clinically inferior to CBZ for measures of its efficacy. No consistent differences in QoL outcomes were found between treatment groups. Health economic analysis supported LTG being preferred to CBZ for both cost per seizure avoided and cost per quality-adjusted life-year gained. In Arm B for time to treatment failure, VPS, the standard drug, was preferred to both TPM and LTG, as it was the drug least likely to be associated with treatment failure for inadequate seizure control and was the preferred drug for time to achieving a 12-month remission. QoL assessments did not show any between-treatment differences. The health economic assessment supported the conclusion that VPS should remain the drug of first choice for idiopathic generalised or unclassified epilepsy, although there is a suggestion that TPM is a cost-effective alternative to VPS. CONCLUSIONS: The evidence suggests that LTG may be a clinical and cost-effective alternative to the existing standard drug treatment, CBZ, for patients diagnosed as having partial seizures. For patients with idiopathic generalised epilepsy or difficult to classify epilepsy, VPS remains the clinically most effective drug, although TPM may be a cost-effective alternative for some patients. Three new antiepileptic drugs have recently been licensed in the UK for the treatment of epilepsy (levetiracetam, zonisamide and pregabalin), therefore these drugs should be compared in a similarly designed trial.

A comparison of the 'cost per child treated' at a primary care-based sedation referral service, compared to a general anaesthetic in hospital.

AIM: To compare the cost-effectiveness of dental sedation techniques used in the treatment of children, focusing on hospital-based dental general anaesthetic (DGA) and advanced conscious sedation in a controlled primary care environment. METHODS: Data on fees, costs and treatment pathways were obtained from a primary care clinic specialising in advanced sedation techniques. For the hospital-based DGA cohort, data were gathered from hospital trusts in the same area. Comparison was via an average cost per child treated and subsequent sensitivity analysis. RESULTS: Analysing records spanning one year, the average cost per child treated via advanced conscious sedation was pound245.47. As some treatments fail (3.5% of cases attempted), and the technique is not deemed suitable for all patients (4-5%), DGA is still required and has been factored into this cost. DGA has an average cost per case treated of pound359.91, 46.6% more expensive than advanced conscious sedation. These cost savings were robust to plausible variation in all parameters. CONCLUSION: The costs of advanced conscious sedation techniques, applied in a controlled primary care environment, are substantially lower than the equivalent costs of hospital-based DGA, informing the debate about the optimum way of managing this patient group.

Vascular patients' preferences for local treatment: an application of conjoint analysis.

OBJECTIVES: To investigate whether and to what extent vascular patients are willing to trade expected health outcomes for improvements in non-health benefits, such as the availability of local services, in the provision of peripheral vascular surgery. METHODS: Conjoint analysis was used to elicit patient preferences via a mailed questionnaire. Respondents were asked to consider pairwise descriptions of vascular services described in terms of a number of key attributes and asked to indicate which scenario description they preferred. Multivariate regression analysis was used to estimate the relative importance of the attributes to respondents. RESULTS: Of the 339 patients invited to participate, 161 (47%) returned a completed questionnaire, although 36 (11%) were found to be internally inconsistent and could not be used, leaving 125 (36%) for analysis. An unexpected problem arose with respect to the design of the conjoint analysis questionnaire. Specifically, three of the attributes in the regression model were found to be collinear. The source of this problem, how it was overcome and how it can be avoided in future studies is discussed. The results of the regression analysis indicated that the patients who responded had a preference for local treatment to the extent that they were willing to incur increased risks of perioperative mortality and amputation to receive treatment at their local hospital. These results are discussed in connection with those from a different study which elicited patient preferences for local treatment using a standard gamble technique. CONCLUSIONS: Policy-makers, when considering the potential benefits of regionalising health care, should seek to elicit the preferences of those patients who will be affected by the reorganisation.

Is there a positive volume-outcome relationship in peripheral vascular surgery? Results of a systematic review.

OBJECTIVES: to examine the evidence for the existence, or otherwise, of a positive volume-outcome relationship in the area of peripheral vascular surgery. DESIGN: systematic overview of prospective or retrospective volume-outcome studies. DATA SOURCES: seven bibliographic databases were searched for English-language articles published between 1986 and 1998. STUDY SELECTION: thirty-six articles published in peer-reviewed journals; excluding editorials, letters or abstracts; and addressing volume and outcome in peripheral vascular surgery. Criteria were applied and agreed by consensus between two of the authors. DATA EXTRACTION: the articles identified were independently assessed by two of the authors. Studies were categorised into three distinct areas - carotid endarterectomy- (17 studies), abdominal aortic aneurysm repair (16 studies) and other vascular interventions (four studies). Within each category studies were further classified according to full adjustment, partial adjustment or no adjustment for case mix. Where discrepancies arose, decisions were referred to a third author for arbitration. DATA SYNTHESIS: findings for carotid endarterectomy identified a positive volume-outcome relationship for both mortality and stroke at the physician level. There was less support for a positive relationship for mortality at the hospital level, and no evidence of benefits for stroke in higher volume hospitals. If only studies making a full adjustment for case mix are included, there is no clear support from statistically significant evidence for or against a positive volume-outcome relationship. For repair of unruptured abdominal aortic aneurysms there is evidence of a positive volume-outcome relationship at both the physician and hospital level, with evidence being particularly strong at the level of the hospital. For ruptured aneurysms the evidence is suggestive of there not being a positive volume-outcome relationship at the hospital level, while for physicians the evidence is more balanced with no clear support either way. For other vascular interventions there were insufficient studies (n=4) from which to draw meaningful conclusions. CONCLUSIONS: our results show that evidence of a relationship between volume and outcome in peripheral vascular surgery may be attributable to factors such as lack of adjustment for case-mix, different definitions of volume and poor quality of studies, especially those of retrospective design. Future studies should address these deficiencies by making full adjustment for case mix and by being prospective in design.

Quantifying patient preferences for out-of-hours primary care.

OBJECTIVE: To quantify public preferences for different attributes of out-of-hours primary medical care. METHODS: This study applies a technique called conjoint analysis. A focus group was convened to identify the most important attributes for inclusion in the study, followed by a postal questionnaire asking people to choose between hypothetical services containing different mixes of these attributes. Multi-variate regression analysis estimated the relative importance of different attributes to respondents. The respondents were 436 adults who were among respondents to an earlier postal survey of 25,090 randomly selected Sheffield residents. RESULTS: The doctor's manner (whether the doctor takes time to listen), the type of consultation (whether the patient receives a home visit, telephone advice, sees an accident and emergency doctor or attends a primary care treatment centre) and waiting time for consultation best predicted the public's preferences for out-of-hours care. Another three attributes--ease of access; seeing a familiar doctor; and the doctor's shift arrangements--were not statistically significant. CONCLUSIONS: By asking people to make simple choices between hypothetical services, it is possible to quantify their strength of preference for different aspects of a service. This has important implications for the planning of services. Specifically, for out-of-hours services, more consideration should be given to the doctor's manner and waiting times rather than familiarity of doctor.

Costing vascular surgery: A review of current reporting practice.

OBJECTIVE: The objective of this study was to assess the level of reporting in economic studies in the area of peripheral vascular disease. Adequate reporting of data is necessary to judge the quality of economic studies by means of critical appraisal criteria. METHODS: A systematic review of the journal literature between 1986 and the first half of 1997 was undertaken. Studies that have attempted to estimate the resource consequences of one or more vascular procedure were the focus of the review. The extent of reporting in each study was assessed by using published guidelines. RESULTS: The review identified 30 articles from nine different countries for inclusion in the study. Of these, more than half were published in the last 2(1/2) years of the search period, indicating a recent and rapid growth in economic studies in this area. When subjected to the reporting guidelines, the studies performed rather poorly overall. CONCLUSIONS: Although the vascular studies can be criticized for inadequate reporting of economic data, it appears from the limited evidence from elsewhere that inadequate reporting is a problem in other clinical areas. In view of the importance of reporting to the ability to critically assess studies-and thus separate the "good" from the "bad"-there is a need for reporting to improve future published studies.

What price information? Modelling threshold probabilities of fetal loss.

This paper is an extension of previous work in which an alternative method of measuring the benefits of antenatal screening was proposed. The method is based on the elicitation of threshold probabilities of fetal loss at which women would be indifferent between having and not having an amniocentesis for the prenatal diagnosis of fetal abnormalities. The aim of this paper is to extend the previous work by modelling the preferences of a larger sample of women and investigating the consistency and validity of their responses. The threshold probabilities are elicited using standard gambles and modelled using Tobit estimation. The results indicate that it is possible to model these probabilities in this way and that it is possible to obtain a high degree of consistency in response to standard gamble questions. While establishing the validity of the responses is more difficult there is some evidence that the technique can provide valid responses.

Estimating the benefits of community water fluoridation using the willingness-to-pay technique: results of a pilot study.

OBJECTIVES: To estimate the health and non-health effects of fluoridation on well-being using the willingness-to-pay technique. METHODS: A pilot study of 100 people was undertaken in which the willingness-to-pay technique was used to estimate the welfare effects of community water fluoridation in the city of Sheffield, in the United Kingdom. In view of the pilot nature of the study, it was decided to use quota sampling based on age and sex rather than random sampling. Reasons for respondents' answers and their previous knowledge of fluoridation were also noted. RESULTS: Sixty-two percent of respondents were in favour of fluoridation, 31% were opposed, and 7% were unsure. Thirty-one respondents refused to answer the willingness-to-pay questions. The mean willingness to pay for those in favour of fluoridation was less than that for those opposed to fluoridation. The main reasons given for opposing fluoridation were its impact on freedom of choice and the desire for pure water. Nineteen percent of the sample held incorrect information on the effects of fluoridation. CONCLUSIONS: The study illustrates how a simple referendum can miss important information regarding the intensity of individuals' preferences. An important aspect of the willingness-to-pay technique is its ability to identify 'losers' and quantify their welfare loss. This issue has been ignored by all previous economic evaluations of fluoridation. Further investigation is required to replicate this work on a larger sample of individuals, and to develop the willingness-to-pay technique.

Methodological issues in the application of conjoint analysis in health care.

This paper adds to an increasing literature on methodological questions addressed in the application of conjoint analysis (CA) in health care. Three issues are addressed: ordering effects; internal validity; and internal consistency. The results of an application of CA in a primary care setting provide no evidence that the ordering of scenarios was important. Evidence was found of both internal validity and internal consistency. In addition, individual preferences were found to be determined by experiences, which raise potentially important questions regarding the elicitation and use of such preferences in economic evaluation.