Long-term Clinical and Cost-effectiveness of Early Endovenous Ablation in Venous Ulceration: A Randomized Clinical Trial

Importance

One-year outcomes from the Early Venous Reflux Ablation (EVRA) randomized trial showed accelerated venous leg ulcer healing and greater ulcer-free time for participants who are treated with early endovenous ablation of lower extremity superficial reflux.

Objective

To evaluate the clinical and cost-effectiveness of early endovenous ablation of superficial venous reflux in patients with venous leg ulceration.

Design, Setting, and Participants

Between October 24, 2013, and September 27, 2016, the EVRA randomized clinical trial enrolled 450 participants (450 legs) with venous leg ulceration of less than 6 months' duration and superficial venous reflux. Initially, 6555 patients were assessed for eligibility, and 6105 were excluded for reasons including ulcer duration greater than 6 months, healed ulcer by the time of randomization, deep venous occlusive disease, and insufficient superficial venous reflux to warrant ablation therapy, among others. A total of 426 of 450 participants (94.7%) from the vascular surgery departments of 20 hospitals in the United Kingdom were included in the analysis for ulcer recurrence. Surgeons, participants, and follow-up assessors were not blinded to the treatment group. Data were analyzed from August 11 to November 4, 2019.

Interventions

Patients were randomly assigned to receive compression therapy with early endovenous ablation within 2 weeks of randomization (early intervention, n = 224) or compression with deferred endovenous treatment of superficial venous reflux (deferred intervention, n = 226). Endovenous modality and strategy were left to the preference of the treating clinical team.

Main Outcomes and Measures

The primary outcome for the extended phase was time to first ulcer recurrence. Secondary outcomes included ulcer recurrence rate and cost-effectiveness.

Results

The early-intervention group consisted of 224 participants (mean [SD] age, 67.0 [15.5] years; 127 men [56.7%]; 206 White participants [92%]). The deferred-intervention group consisted of 226 participants (mean [SD] age, 68.9 [14.0] years; 120 men [53.1%]; 208 White participants [92%]). Of the 426 participants whose leg ulcer had healed, 121 (28.4%) experienced at least 1 recurrence during follow-up. There was no clear difference in time to first ulcer recurrence between the 2 groups (hazard ratio, 0.82; 95% CI, 0.57-1.17; P = .28). Ulcers recurred at a lower rate of 0.11 per person-year in the early-intervention group compared with 0.16 per person-year in the deferred-intervention group (incidence rate ratio, 0.658; 95% CI, 0.480-0.898; P = .003). Time to ulcer healing was shorter in the early-intervention group for primary ulcers (hazard ratio, 1.36; 95% CI, 1.12-1.64; P = .002). At 3 years, early intervention was 91.6% likely to be cost-effective at a willingness to pay of £20 000 ($26 283) per quality-adjusted life year and 90.8% likely at a threshold of £35 000 ($45 995) per quality-adjusted life year.

Conclusions and Relevance

Early endovenous ablation of superficial venous reflux was highly likely to be cost-effective over a 3-year horizon compared with deferred intervention. Early intervention accelerated the healing of venous leg ulcers and reduced the overall incidence of ulcer recurrence.

Trial Registration

ClinicalTrials.gov identifier: ISRCTN02335796.

Study protocol for a multicentre, randomised controlled trial to compare the use of the decellularised dermis allograft in addition to standard care versus standard care alone for the treatment of venous leg ulceration: DAVE trial

INTRODUCTION

Venous leg ulceration (VLU), the most common type of chronic ulcer, can be difficult to heal and is a major cause of morbidity and reduced quality of life. Although compression bandaging is the principal treatment, it is time-consuming and bandage application requires specific training. There is evidence that intervention on superficial venous incompetence can help ulcer healing and recurrence, but this is not accessible to all patients. Hence, new treatments are required to address these chronic wounds. One possible adjuvant treatment for VLU is human decellularised dermis (DCD), a type of skin graft derived from skin from deceased tissue donors. Although DCD has the potential to promote ulcer healing, there is a paucity of data for its use in patients with VLU.

METHODS AND ANALYSIS

This is a multicentre, parallel group, pragmatic randomised controlled trial. One hundred and ninety-six patients with VLU will be randomly assigned to receive either the DCD allograft in addition to standard care or standard care alone. The primary outcome is the proportion of participants with a healed index ulcer at 12 weeks post-randomisation in each treatment arm. Secondary outcomes include the time to index ulcer healing and the proportion of participants with a healed index ulcer at 12 months. Changes in quality of life scores and cost-effectiveness will also be assessed. All analyses will be carried out on an intention-to-treat (ITT) basis. A mixed-effects, logistic regression on the outcome of the proportion of those with the index ulcer healed at 12 weeks will be performed. Secondary outcomes will be assessed using various statistical models appropriate to the distribution and nature of these outcomes.

ETHICS AND DISSEMINATION

Ethical approval was granted by the Bloomsbury Research Ethics Committee (19/LO/1271). Findings will be published in a peer-reviewed journal and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

ISRCTN21541209.

Primary care survey of venous leg ulceration management and referral pre-EVRA trial

Venous leg ulceration (VLU) is a public health concern that is largely managed in community settings. The present study aimed to survey current VLU management in the community. A 14-question survey was distributed to primary care professionals, and 90 responses were received. Some 54% of respondents stated that they would assess ankle brachial pressure indices (ABPI) for those with VLU, while 25% reported that they would not. Additionally, 62% reported not organising duplex ultrasound scanning. Compression therapy was offered by 82% of respondents. When asked whether VLU patients were referred to specialist services in secondary or tertiary care, some 32% reported that they would. However, 57% reported that, if a study suggested that referral to specialist services was beneficial, they would change their practice. On the basis of the findings, the authors concluded that there is diversity in VLU diagnostic and treatment pathways. New, high-quality evidence may improve practice, but care delivery is influenced by local factors including time and resource distribution.

The management of venous leg ulceration post the EVRA (early venous reflux ablation) ulcer trial: Management of venous ulceration post EVRA

Objectives

This survey study evaluates current management strategies for venous ulceration and the impacts of the EVRA trial results.

Methods

An online survey was disseminated to approximately 15000 clinicians, through 12 vascular societies in 2018. Survey themes included: referral times, treatment times and strategies, knowledge of the EVRA trial and service barriers to managing venous ulceration. Data analysis was performed using Microsoft Excel and SPSS.

Results

664 responses were received from 78 countries. Respondents were predominantly European (55%) and North American (23%) vascular surgeons (74%). Responses varied between different countries. The median vascular clinic referral time was 6 weeks and time to be seen in clinic was 2 weeks. This was significantly higher in the UK (p ≤ 0.02). 77% of respondents performed surgical/endovenous interventions prior to ulcer healing, the median time to intervention was 4 weeks. 31% of participants changed their practice following EVRA. Frequently encountered barriers to implementing change were a lack of operating space/time (18%).

Conclusion

Venous ulcers are not managed as quickly as they should be. An evaluation of local resource requirements should be performed to improve service provision for venous ulceration. When interpreting the results of this survey consideration should be given to the response rate.

Early versus deferred endovenous ablation of superficial venous reflux in patients with venous ulceration: the EVRA RCT

BACKGROUND

Venous ulceration is a common and costly health-care issue worldwide, with poor healing rates greatly affecting patient quality of life. Compression bandaging has been shown to improve healing rates and reduce recurrence, but does not address the underlying cause, which is often superficial venous reflux. Surgical correction of the reflux reduces ulcer recurrence; however, the effect of early endovenous ablation of superficial venous reflux on ulcer healing is unclear.

OBJECTIVES

To determine the clinical effectiveness and cost-effectiveness of compression therapy with early endovenous ablation of superficial venous reflux compared with compression therapy with deferred endovenous ablation in patients with venous ulceration.

DESIGN

A pragmatic, two-arm, multicentre, parallel-group, open randomised controlled trial with a health economic evaluation.

SETTING

Secondary care vascular centres in England.

PARTICIPANTS

Patients aged ≥ 18 years with a venous leg ulcer of between 6 weeks' and 6 months' duration and an ankle-brachial pressure index of ≥ 0.8 who could tolerate compression and were deemed suitable for endovenous ablation of superficial venous reflux.

INTERVENTIONS

Participants were randomised 1 : 1 to either early ablation (compression therapy and superficial endovenous ablation within 2 weeks of randomisation) or deferred ablation (compression therapy followed by endovenous ablation once the ulcer had healed).

MAIN OUTCOME MEASURES

The primary outcome measure was time from randomisation to ulcer healing, confirmed by blinded assessment. Secondary outcomes included 24-week ulcer healing rates, ulcer-free time, clinical success (in addition to quality of life), costs and quality-adjusted life-years (QALYs). All analyses were performed on an intention-to-treat basis.

RESULTS

A total of 450 participants were recruited (224 to early and 226 to deferred superficial endovenous ablation). Baseline characteristics were similar between the two groups. Time to ulcer healing was shorter in participants randomised to early superficial endovenous ablation than in those randomised to deferred ablation [hazard ratio 1.38, 95% confidence interval (CI) 1.13 to 1.68; p = 0.001]. Median time to ulcer healing was 56 (95% CI 49 to 66) days in the early ablation group and 82 (95% CI 69 to 92) days in the deferred ablation group. The ulcer healing rate at 24 weeks was 85.6% in the early ablation group, compared with 76.3% in the deferred ablation group. Median ulcer-free time was 306 [interquartile range (IQR) 240-328] days in the early ablation group and 278 (IQR 175-324) days in the deferred endovenous ablation group (p = 0.002). The most common complications of superficial endovenous ablation were pain and deep-vein thrombosis. Differences in repeated measures of Aberdeen Varicose Vein Questionnaire scores (p < 0.001), EuroQol-5 Dimensions index values (p = 0.03) and Short Form questionnaire-36 items body pain (p = 0.05) over the follow-up period were observed, in favour of early ablation. The mean difference in total costs between the early ablation and deferred ablation groups was £163 [standard error (SE) £318; p = 0.607]; however, there was a substantial and statistically significant gain in QALY over 1 year [mean difference between groups 0.041 (SE 0.017) QALYs; p = 0.017]. The incremental cost-effectiveness ratio of early ablation at 1 year was £3976 per QALY, with a high probability (89%) of being more cost-effective than deferred ablation at conventional UK decision-making thresholds (currently £20,000 per QALY). Sensitivity analyses using alternative statistical models give qualitatively similar results.

LIMITATIONS

Only 7% of screened patients were recruited, treatment regimens varied significantly and technical success was assessed only in the early ablation group.

CONCLUSIONS

Early endovenous ablation of superficial venous reflux, in addition to compression therapy and wound dressings, reduces the time to healing of venous leg ulcers, increases ulcer-free time and is highly likely to be cost-effective.

FUTURE WORK

Longer-term follow-up is ongoing and will determine if early ablation will affect recurrence rates in the medium and long term.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN02335796.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 24. See the NIHR Journals Library website for further project information.

UK primary care survey of venous leg ulceration management and referral - Post-EVRA trial

Objective

Determine standards of referral and management of patients with venous leg ulceration in primary care after the release of the EVRA (A Randomized Trial of Early Endovenous Ablation in Venous Ulceration) study results.

Methods

An online questionnaire was disseminated over four months to professionals working within primary care.

Results

The survey received 643 responses. Of respondents, 90 (14%) had heard of the EVRA trial and 51 (8%) were familiar with the results. Of those who answered the following questions, 410 (69.1%) stated that referral to a vascular specialist must be made by the General Practitioner and 13 (2.2%) reported that they would always refer patients for secondary care assessment before the publication of EVRA. Considering the EVRA results, 128 (29%) reported that they would change practice regarding referral and would experience no barriers and 198 (45%) reported that they would like to refer earlier but is not their decision. Barriers to changing practice included local referral policies, training and time restrictions, 266 (59%) had heard of the NICE guideline (CG168) and 194 (43%) were aware of the recommendations for referral to a vascular service within two weeks for patients with an open or healed ulcer.

Conclusion

There is a considerable variation in local referral pathways for venous leg ulceration, and despite clinicians wanting to refer promptly, many primary care professionals are unable to. Unfortunately, the EVRA study alone may not change the overall practice, and work is needed to overcome barriers faced by primary care professionals.

The global management of leg ulceration: Pre early venous reflux ablation trial

BACKGROUND

Various guidelines exist worldwide for the diagnosis and management of venous leg ulcers; however, these are difficult to implement resulting in disparate treatment of patients globally.

METHOD

An online, 26-question survey was designed to evaluate the current global management of venous leg ulceration and was emailed globally to approximately 15,000 participants (November 2017-February 2018).

RESULTS

Overall, 799 responses were received from 86 countries, with a 5% response rate. The respondent physicians saw a median of 10 (interquartile range 5-20) patients per month, with a median time to referral from primary to secondary care of six weeks. Of the respondents, 61% arranged an ankle brachial pressure index on first visit and 84% performed a venous duplex, with 95% prescribing compression for those in whom it was not contraindicated. Fifty-nine percent performed endovenous intervention or surgery prior to ulcer healing.

CONCLUSIONS

The survey showed a diversity of treatment pathways. The need to develop a robust, clear pathway for patients with leg ulceration is clearly required.

Cost-effectiveness analysis of a randomized clinical trial of early versus deferred endovenous ablation of superficial venous reflux in patients with venous ulceration

BACKGROUND

Treatment of superficial venous reflux in addition to compression therapy accelerates venous leg ulcer healing and reduces ulcer recurrence. The aim of this study was to evaluate the costs and cost-effectiveness of early versus delayed endovenous treatment of patients with venous leg ulcers.

METHODS

This was a within-trial cost-utility analysis with a 1-year time horizon using data from the EVRA (Early Venous Reflux Ablation) trial. The study compared early versus deferred endovenous ablation for superficial venous truncal reflux in patients with a venous leg ulcer. The outcome measure was the cost per quality-adjusted life-year (QALY) over 1 year. Sensitivity analyses were conducted with alternative methods of handling missing data, alternative preference weights for health-related quality of life, and per protocol.

RESULTS

After early intervention, the mean(s.e.m.) cost was higher (difference in cost per patient £163(318) (€184(358))) and early intervention was associated with more QALYs at 1 year (mean(s.e.m.) difference 0·041(0·017)). The incremental cost-effectiveness ratio (ICER) was £3976 (€4482) per QALY. There was an 89 per cent probability that early venous intervention is cost-effective at a threshold of £20 000 (€22 546)/QALY. Sensitivity analyses produced similar results, confirming that early treatment of superficial reflux is highly likely to be cost-effective.

CONCLUSION

Early treatment of superficial reflux is highly likely to be cost-effective in patients with venous leg ulcers over 1 year. Registration number: ISRCTN02335796 (http://www.isrctn.com).

A Randomized Trial of Early Endovenous Ablation in Venous Ulceration

BACKGROUND

Venous disease is the most common cause of leg ulceration. Although compression therapy improves venous ulcer healing, it does not treat the underlying causes of venous hypertension. Treatment of superficial venous reflux has been shown to reduce the rate of ulcer recurrence, but the effect of early endovenous ablation of superficial venous reflux on ulcer healing remains unclear.

METHODS

In a trial conducted at 20 centers in the United Kingdom, we randomly assigned 450 patients with venous leg ulcers to receive compression therapy and undergo early endovenous ablation of superficial venous reflux within 2 weeks after randomization (early-intervention group) or to receive compression therapy alone, with consideration of endovenous ablation deferred until after the ulcer was healed or until 6 months after randomization if the ulcer was unhealed (deferred-intervention group). The primary outcome was the time to ulcer healing. Secondary outcomes were the rate of ulcer healing at 24 weeks, the rate of ulcer recurrence, the length of time free from ulcers (ulcer-free time) during the first year after randomization, and patient-reported health-related quality of life.

RESULTS

Patient and clinical characteristics at baseline were similar in the two treatment groups. The time to ulcer healing was shorter in the early-intervention group than in the deferred-intervention group; more patients had healed ulcers with early intervention (hazard ratio for ulcer healing, 1.38; 95% confidence interval [CI], 1.13 to 1.68; P=0.001). The median time to ulcer healing was 56 days (95% CI, 49 to 66) in the early-intervention group and 82 days (95% CI, 69 to 92) in the deferred-intervention group. The rate of ulcer healing at 24 weeks was 85.6% in the early-intervention group and 76.3% in the deferred-intervention group. The median ulcer-free time during the first year after trial enrollment was 306 days (interquartile range, 240 to 328) in the early-intervention group and 278 days (interquartile range, 175 to 324) in the deferred-intervention group (P=0.002). The most common procedural complications of endovenous ablation were pain and deep-vein thrombosis.

CONCLUSIONS

Early endovenous ablation of superficial venous reflux resulted in faster healing of venous leg ulcers and more time free from ulcers than deferred endovenous ablation. (Funded by the National Institute for Health Research Health Technology Assessment Program; EVRA Current Controlled Trials number, ISRCTN02335796 .).

Cost-effectiveness of treatments for superficial venous reflux in patients with chronic venous ulceration

Background

Venous leg ulcers impair quality of life significantly, with substantial costs to health services. The aim of this study was to estimate the cost‐effectiveness of interventional procedures alongside compression therapy versus compression therapy alone for the treatment of chronic venous leg ulceration.

Methods

A Markov decision analytical model was developed. The main outcome measures were quality‐adjusted life‐years (QALYs) and lifetime costs per patient, from the perspective of the UK National Health Service at 2015 prices. Resource use included the initial procedures, compression therapy, primary care and outpatient consultations. The interventional procedures included superficial venous surgery, endothermal ablation and ultrasound‐guided foam sclerotherapy (UGFS). The study population was patients with a chronic venous ulcer who were eligible for either compression therapy or an interventional procedure. Data were obtained from systematic review and meta‐analysis of RCTs.

Results

Surgery gained 0·112 (95 per cent c.i. −0·011 to 0·213) QALYs compared with compression therapy alone, with a difference in lifetime costs of €−1330 (−3570 to 1262). Given the expected savings in community care, the procedure would pay for itself within 4 years. There was insufficient evidence regarding endothermal ablation and UGFS to draw conclusions.

Discussion

This modelling study found surgery to be more effective and less costly than compression therapy alone. Further RCT evidence is required for both endothermal ablation and UGFS.

Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm

BACKGROUND

Single-centre series of the management of patients with ruptured abdominal aortic aneurysm (AAA) are usually too small to identify clinical factors that could improve patient outcomes.

METHODS

IMPROVE is a pragmatic, multicentre randomized clinical trial in which eligible patients with a clinical diagnosis of ruptured aneurysm were allocated to a strategy of endovascular aneurysm repair (EVAR) or to open repair. The influences of time and manner of hospital presentation, fluid volume status, type of anaesthesia, type of endovascular repair and time to aneurysm repair on 30-day mortality were investigated according to a prespecified plan, for the subgroup of patients with a proven diagnosis of ruptured or symptomatic AAA. Adjustment was made for potential confounding factors.

RESULTS

Some 558 of 613 randomized patients had a symptomatic or ruptured aneurysm: diagnostic accuracy was 91·0 per cent. Patients randomized outside routine working hours had higher operative mortality (adjusted odds ratio (OR) 1·47, 95 per cent confidence interval 1·00 to 2·17). Mortality rates after primary and secondary presentation were similar. Lowest systolic blood pressure was strongly and independently associated with 30-day mortality (51 per cent among those with pressure below 70 mmHg). Patients who received EVAR under local anaesthesia alone had greatly reduced 30-day mortality compared with those who had general anaesthesia (adjusted OR 0·27, 0·10 to 0·70).

CONCLUSION

These findings suggest that the outcome of ruptured AAA might be improved by wider use of local anaesthesia for EVAR and that a minimum blood pressure of 70 mmHg is too low a threshold for permissive hypotension.

Endovascular or open repair strategy for ruptured abdominal aortic aneurysm: 30 day outcomes from IMPROVE randomised trial

OBJECTIVE

To assess whether a strategy of endovascular repair (if aortic morphology is suitable, open repair if not) versus open repair reduces early mortality for patients with suspected ruptured abdominal aortic aneurysm.

DESIGN

Randomised controlled trial.

SETTING

30 vascular centres (29 UK, 1 Canadian), 2009-13.

PARTICIPANTS

613 eligible patients (480 men) with a clinical diagnosis of ruptured aneurysm.

INTERVENTIONS

316 patients were randomised to the endovascular strategy (275 confirmed ruptures, 174 anatomically suitable for endovascular repair) and 297 to open repair (261 confirmed ruptures).

MAIN OUTCOME MEASURES

30 day mortality, with 24 hour and in-hospital mortality, costs, and time and place of discharge as secondary outcomes.

RESULTS

30 day mortality was 35.4% (112/316) in the endovascular strategy group and 37.4% (111/297) in the open repair group: odds ratio 0.92 (95% confidence interval 0.66 to 1.28; P=0.62); odds ratio after adjustment for age, sex, and Hardman index 0.94 (0.67 to 1.33). Women may benefit more than men (interaction test P=0.02) from the endovascular strategy: odds ratio 0.44 (0.22 to 0.91) versus 1.18 (0.80 to 1.75). 30 day mortality for patients with confirmed rupture was 36.4% (100/275) in the endovascular strategy group and 40.6% (106/261) in the open repair group (P=0.31). More patients in the endovascular strategy than in the open repair group were discharged directly to home (189/201 (94%) v 141/183 (77%); P<0.001). Average 30 day costs were similar between the randomised groups, with an incremental cost saving for the endovascular strategy versus open repair of £1186 (€1420; $1939) (95% confidence interval -£625 to £2997).

CONCLUSIONS

A strategy of endovascular repair was not associated with significant reduction in either 30 day mortality or cost. Longer term cost effectiveness evaluations are needed to assess the full effects of the endovascular strategy in both men and women.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN48334791.

The cost-effectiveness of magnetic resonance imaging for investigation of the knee joint

OBJECTIVES

This study considered the role of magnetic resonance imaging (MRI) in the diagnosis of knee injuries in a district general hospital (DGH) setting. The principal objective was to identify whether the use of MRI had a major impact on the clinical management of patients presenting with chronic knee problems, in whom surgery was being considered, whether it reduced overall costs and whether it improved patient outcome. In addition, the research: (1) explored the 'diagnostic accuracy' of initial clinical investigation of the knee by an orthopaedic trainee, consultant knee specialist and consultant radiologist; (2) considered the variability and diagnostic accuracy of interpretations of knee MRI investigations between radiologists; (3) measured the strength of preference for the potential diagnostic/therapeutic impact of knee MRI (i.e. the avoidance of surgery). METHODS - RANDOMISED CONTROLLED TRIAL: The research was based on a single-centre randomised controlled trial conducted at Kent and Canterbury Hospital. Patients attending with knee problems in whom surgery was being considered were recruited from routine orthopaedic clinics. Most patients had been referred by their general practitioner. Patients were randomised to either investigation using an MRI scan (MRI trial arm) or investigation using arthroscopy (no-MRI trial arm). The study investigated the benefits of knee MRI at two levels: diagnostic/therapeutic impact (i.e. avoidance of surgery) and patient outcome (using the Short Form with 36 items and EQ-5D quality-of-life measurement instruments). Quality of life was assessed at baseline and at 6 and 12 months. Costs were assessed from the perspectives of the NHS and patients. All analyses were by intention to treat. METHODS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): For the investigation of diagnostic accuracy of initial clinical investigation, the sample comprised 114 patients recruited in a separate study conducted at St Thomas' Hospital. The sample was drawn from patients presenting at the Accident and Emergency Department with an acute knee injury. All study patients received an MRI scan, but initial diagnosis was made without access to the scan or the radiologist's report. After 12 months, all clinical notes and MRI scans of study patients were reviewed and a final 'reference standard' diagnosis for each patient was reached. Comparison was made between the diagnosis recorded by each clinician (i.e. orthopaedic trainee, knee specialist and consultant radiologist) and the reference diagnosis. METHODS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): For this substudy, the MRI images from 80 patients (recruited at St Thomas' Hospital) were interpreted independently by seven consultant radiologists at DGHs and the St Thomas' Hospital MRI radiologist. For each area of the knee, the level of agreement (measured using weighted kappa) between the responses of the eight radiologists and the reference standard diagnosis was assessed. METHODS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The investigation of potential patient preferences for the diagnostic/therapeutic impact of MRI was explored using a discrete choice conjoint measurement research design. Choices involved selecting between two alternative scenarios described using four attributes, and data were collected from 585 undergraduate sports science students and analysed using a random-effects probit model. RESULTS - RANDOMISED CONTROLLED TRIAL: The trial recruited 118 patients (59 randomly allocated to each arm). The two groups were similar in important respects at baseline. The central finding was of no statistically significant differences between groups in all measures of health outcome, although a trend in favour of the no-MRI group was observed. However, the use of MRI was found to be associated with a positive diagnostic/therapeutic impact: a significantly smaller proportion of patients in the MRI group underwent surgery (MRI = 0.41, no-MRI = 0.71; p = 0.001). There was a similar mean overall NHS cost for both groups. RESULTS - SUBSTUDIES (INVESTIGATION OF DIAGNOSTIC ACCURACY): The exploration of diagnostic accuracy found that, when compared to orthopaedic trainees (44% correct diagnoses) or to radiologists reporting an MRI scan (68% correct diagnoses), the accuracy rate was higher for knee specialists (72% correct diagnoses). RESULTS - SUBSTUDIES (INVESTIGATION OF THE GENERALISABILITY OF RESULTS): This generalisability study indicated that, in general terms, radiologists in DGHs provide accurate interpretations of knee MRI images that are similar to a radiologist at a specialist centre. The one area of the knee for which this did not hold was the lateral collateral ligament. RESULTS - SUBSTUDIES (INVESTIGATION OF PREFERENCES): The central finding for this substudy was that, on average and within the range specified, choices in this group of potential patients were not significantly influenced by variation in the chance of avoiding surgery. CONCLUSIONS - IMPLICATIONS FOR HEALTHCARE: The evidence presented in this report supports the conclusions that the use of MRI in patients presenting at DGHs with chronic knee problems in whom arthroscopy was being considered did not increase NHS costs overall, was not associated with significantly worse outcomes and avoided surgery in a significant proportion of patients. CONCLUSIONS - RECOMMENDATIONS FOR FURTHER RESEARCH (IN PRIORITY ORDER): (1) The trial data demonstrated that the use of MRI in patients with chronic knee problems reduced the need for surgery. However, the link between diagnostic processes and changes in health outcome is indirect and the finding of no-MRI-related effect on health outcome may, therefore, be a consequence of the limited power of the trial. Further research to confirm (or contradict) these findings would be valuable. (2) The investigation of diagnostic accuracy involved comparison with a reference diagnosis established by a panel of two clinical members of the research team. It would be interesting to explore the extent to which the results would differ using an external panel. (3) The result from the preference study, indicating that the potential diagnostic/therapeutic impact of knee MRI was not highly valued, is a surprising finding that would be important to explore in general public or patient populations. (4) The focus for the trial-based aspects of this research was the DGH and patients presenting with chronic knee problems who were being considered for surgery. Care should be taken in generalising from these results to other patient groups (e.g. acute knee injuries) or to other settings (e.g. specialist centres). Further clinical trials would be required in order to answer such questions.

Hyaluronan forms specific stable tertiary structures in aqueous solution: a 13C NMR study

13C NMR spectra of aqueous solutions of hyaluronan (HA) of high molecular mass, before and after digestion with testicular hyaluronidase, and of hyaluronan methyl ester were obtained at 125.8 MHz. Carbonyl peaks were assigned by using selective decoupling techniques. Spectra of digested and undigested HA showed sharp signals, except for that assigned to the acetamido carbonyl carbon in the high polymer, which was much broadened. The decreased mobility of this C==O, thus demonstrated, was caused by restricted rotation. As part of the rigid CO---NH unit, rotation of NH was therefore similarly restricted, probably because of an intermolecular H bond from NH to carboxylate groups on neighbouring HA molecules. This bond was confirmed by comparing esterified HA with unmodified HA. Methyl esterification of carboxylates was accompanied by changes in acetamido C==O resonances consistent with increased mobility of CO---NH groups. Ester C==O resonances were sharp, proving that they did not participate in sterically restricted structures such as the proposed H bonds involving unesterified carboxylate groups. C==O resonances report on the environments and on the interrelationships of amide and carboxylate groups. A detailed structure suggested for high-molecular-mass HA in aqueous solution takes account of NMR and x-ray fiber diffraction data. Antiparallel HA chains overlap in meshworks stabilized by specific H bonds and hydrophobic bonds. This highly cooperative structure, formally equivalent to beta-sheets seen in proteins, is not stable in low-molecular-mass HA solution. The results relate to structures proposed for shape modules in extracellular matrix involving chondroitin and keratan sulfates, which resemble HA in their stereochemistry.

In vivo corrosion of 316L stainless-steel hip implants: morphology and elemental compositions of corrosion products

Eleven surgically retrieved stainless steel implants showing varying degrees of surface corrosion were examined to characterize the morphology and composition of corrosion products. The implants were fabricated to the specification AISI316L (Muller) and BS 3531 pt 1 1971-78 (Charnley). They had been in place for 9-21 y (Mean :13 y) and failures were due to aseptic loosening. The morphology and chemical compositions of corrosion products were recorded using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Nine implants had areas of corrosion covering 1-5 cm of the stem, partially or all round. Corrosion existed in layers. The layers consisted either of chromium in association with sulfur, or iron in association with phosphorus. Variable amounts of calcium and chlorine were also present in all layers. Nickel, which makes up 13% of the alloy, was persistently absent. The presence and extent of corrosion was independent of the alloy composition and could not be related to the duration of implantation.

Comparison of secondary structures in water of chondroitin-4-sulfate and dermatan sulfate: implications in the formation of tertiary structures

Chondroitin-4-sulfate (CS4) and dermatan sulfate (DS) were examined in D2O solution, with or without NaCl, by NMR at 300 MHz, to investigate the physicochemical consequences of epimerization of glucuronate (GlcUA in CS4) to iduronate (IdoUA in DS). Nuclear Overhauser effects (NOEs) and spin-lattice relaxation times following selective and nonselective inversion were measured at up to 70 degrees C. (1) NOEs confirmed 4C1 conformations of sugar rings in N-acetylgalactosamine and GlcUA, and 1C4 or 2S0 in IdoUA. Conflict between NMR data and periodate oxidation kinetics over IdoUA conformations is resolvable by postulating conversion of monodentate periodate-1C4 complexes to conformations in which periodate oxidation can procede. (2) Pairs of glycosidic protons in CS4 and DS showed strong NOEs, implying that stretches of 2-fold helix were present, with carboxylate and acetamido groups close to each other on the same side of tapelike molecules, extending previous work in dimethyl sulfoxide solution. CS4 and DS have large hydrophobic patches in this configuration, similar to those in keratan sulfate and hyaluronan. (3) Selective and nonselective inversion-recoveries implied similar segmental and backbone mobilities and hence flexibilities in CS4 and DS. This is discussed in terms of intrinsic flexibility of glycosidic conformations, modified by hydrogen-bonded arrays. (4) We postulate that hydrophobic and hydrogen bonding drives DS self-aggregation. Stronger self-aggregation of DS compared with CS4 is attributed to increased intermolecular hydrogen-bonding in DS, secondary to decreased intramolecular hydrogen-binding. This is partly because the axial OH groups in 1C4 IdoUA cannot hydrogen-bond to neighboring sugars as can the equatorial OH groups in GlcUA of CS4.

A water molecule participates in the secondary structure of hyaluronan

The structure of hyaluronan was investigated in water/dimethyl sulphoxide mixtures by using high-field n.m.r. and space-filling molecular models. The secondary structure previously established in detail in 'dry' dimethyl sulphoxide [Heatley, Scott & Hull (1984) Biochem. J. 220, 197-205] undergoes changes on addition of water, compatible with the incorporation of a water bridge between the uronate carboxylate and acetamido NH groups. Molecular models show that such a configuration is highly probable, and saturation-transfer experiments yield rates of NH proton exchange that support this proposed structure. The existence of two distinct stable configurations for hyaluronan, in water-rich and water-poor conditions respectively, may have biological implications, e.g. during its biosynthesis in cell membranes. There are extensive hydrophobic regions in both forms, which may be important for interactions with e.g., membranes, proteins and itself.

Interaction of some polyhexamethylene biguanides and membrane phospholipids in Escherichia coli

The interaction between some polyhexamethylene biguanides and the cell envelope of Escherichia coli has been investigated. An amine-ended dimer, (AED, n = 2), a polydisperse mixture (ICI plc) available as the active ingredient of Vantocil IB, (PHMB, n = 5.5), and a high molecular weight fraction, (HMW, n = greater than or equal to 10) of PHMB were used. The sensitivity of batch cultures depleted of magnesium (M-dep), phosphorus (P-dep) or glycerol (C-dep) towards the biocides was assessed by monitoring the rate and extent of potassium ion leakage. P-dep suspensions were particularly resistant to all these agents and possessed less than half the quantity of phospholipid of other cell types. This was compensated for by a proportionate increase in fatty acid and neutral lipid content of the cells. The reduction in phospholipid content was accounted for by decreases in phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). Diphosphatidylglycerol (DPG) and phosphatidylserine (PS) content of the cultures remained unaffected by the depleting nutrient. Fourier-transform n.m.r. spectroscopy was used to study proton nuclei during the interaction of HMW, AED and PHMB with various phospholipid-vesicle preparations. The results strongly suggest that the biocides acted preferentially on the acidic phospholipids PG and DPG, rather than towards PE or PS. Resistance of P-dep cultures therefore reflected reductions in PG content. A molecular basis for the interaction of these compounds and membranes is proposed.

Secondary structure of hyaluronate in solution. A 1H-n.m.r. investigation at 300 and 500 MHz in [2H6]dimethyl sulphoxide solution

The 1H-n.m.r. spectra of solutions in [2H6]dimethyl sulphoxide of the sodium salts of tetra-, hexa- and octa-saccharides prepared from hyaluronate by testicular-hyaluronidase digestion were examined at 300 and 500 MHz. The signals from hydroxy groups at positions 2 and 3 in the glucuronic acid moiety were assigned. Their chemical shifts and associated temperature-dependencies, as well as their coupling constants, depended on whether or not the uronic acid was at the non-reducing end. Deviations from the 'normal' pattern of hydroxy-group proton n.m.r. behaviour were attributable to participation in hydrogen bonds, either to the acetamido carbonyl oxygen atom or the pyranose ring oxygen atom of neighbouring N-acetylhexosamine moieties. A secondary structure, containing four different hydrogen bonds per trisaccharide unit of glucuronsyl-hexosaminyl-glucuronic acid, was demonstrated. This is the first complete and detailed secondary structure to be established for hyaluronate in any solvent. Hyaluronate is compared with chondroitin sulphate, dermatan sulphate, heparan sulphate and keratan sulphate in their potential to form secondary structures with features in common. The significance of the details of the structure to its overall stability, and the probability of their persistence into aqueous environments, are discussed. The presence of all or most of the secondary structure in glycosaminoglycuronans is correlated with a space-filling function in the tissue, and with a high carbohydrate content in the parent proteoglycan in the case of the chondroitin sulphates.

Secondary structure of chondroitin sulphate in dimethyl sulphoxide

1H NMR spectra were obtained in fully deuterated dimethyl sulphoxide of sodium chondroitin 4-sulphate and of the tetrasaccharide, hexasaccharide and octasaccharide prepared from it. Two types of NH resonance were observed, at 7.6 ppm and 8.8 ppm. The latter was the only one in the polymer spectrum, whereas both were present in the oligomer spectra: N-acetylchondrosinate produced only the 7.6-ppm signal. The upfield resonance (7.6 ppm) is characteristic of "normal", monomeric acetamido sugars and disaccharides, while the downfield resonance (8.8 ppm) suggests a hydrogen-bonded NH. The elongation of disaccharide to tetrasaccharide produces a new environment, involving a hydrogen bond at the non-reducing disaccharide NH. A structure, with three hydrogen bonds per tetrasaccharide unit, is proposed which accounts for the quantitative and qualitative aspects of the NMR spectra of polymers and oligomers. A laser light-scattering study showed that sodium chondroitin 4-sulphate has the same molecular weight in water as in dimethyl sulphoxide. The observed hydrogen bonds are therefore intramolecular, as required by the proposed structure, and probably exist in water as well as in dimethyl sulphoxide.

Detection of secondary structure in glycosaminoglycans via the H n.m.r. signal of the acetamido NH group

Two simple methods for dissolving salts of acid glycosaminoglycans with inorganic cations (e.g. Li+ and Na+) in dry dimethyl sulphoxide are described. Complete n.m.r. spectra of, e.g., Na+ and Li+ salts of chondroitin sulphate and keratan sulphate were obtained on these solutions. In [2H6]dimethyl sulphoxide the NH resonance of 2-acetamido-2-deoxy hexosides is in the range 7.2-8.0 delta, but is downfield (8.3-9.3 delta) when the NH is H-bonded to -CO2-. Heparan sulphate shows two NH resonances, of which one (at 8.3 delta) is probably indicative of H-bonding. Space-filling models show that a very close approach of NH to -CO2- across the alpha-glucosaminidic bond is possible, and a solution configuration for heparan sulphate is proposed. The n.m.r. results are entirely compatible with interpretations of periodate-oxidation kinetics, based on H-bonded secondary structures present in hyaluronate and chondroitin sulphates, but not in dermatan (or keratan) sulphate.

Synthesis and dopaminergic properties of some exo- and endo-2-aminobenzonorbornenes designed as rigid analogue of dopamine

Stereospecific syntheses of exo-2-amino-5,6-dihydroxybenzonorbornene (11f), exo-2-amino-6,7-dihydroxybenzonorbornene (11h), exo-2-amino-7,8-dihydroxybenzonorbornene (11g), and endo-2-amino-6,7-dihydroxybenzonorbornene (14d), rigid analogues of dopamine, are described. Compounds 11 h and 14d, their N-methyl (11i and 11j) and N,N-dimethyl (14i and 14j) derivatives, and compounds 11f and 11g were inactive as dopamine agonists when evaluated for dopaminergic activity by their ability to induce stereotyped behavior in mice after subcutaneous injection and by their ability to cause hyperactivity in rats after bilateral injection into the nucleus accumbens. However, compounds 11f, 11g, 11h, and the N-methyl derivatives 11i and 14d were all effective in displacing [3H]-2-amino-6,7-dihydroxytetralin ([3H]ADTN) and [3h[-N-n-propylnorapomorphine ([3H]NPA) from rat striatal membranes.

Secondary structure in glycosaminoglycuronans: N.M.R. spectra in dimethyl sulphoxide of disaccharides related to hyaluronic acid and chondroitin sulphate

1H-N.m.r.spectra for solutions in dimethyl sulphoxide-d6 of disaccharides related to hyaluronate and chondroitin sulphate are compared with those of their methylated derivatives. All resonances, including those of HO and HN groups, have been assigned. The temperature and concentration dependences suggest that HO-4 of the hexosamine residue in hyalobiouronate (but not that in chondrosinate) is hydrogen-bonded to O-5 of the uronic acid residue. The resonance of HO-2 of the uronate residue of chondrosinate also shows anomalies that may arise from intra-residue hydrogen-bonding. These findings confirm the existence of some features previously suggested to be present in glycosaminoglycuronan polymers. The resonance of HO-4 of the uronate residue in the disaccharides and in sodium (methyl alpha-D-glucopyranosid)uronate behaves as though there was a hydrogen bond between the carboxylate group and HO-4.

Secondary structures of hyaluronate and chondroitin sulphates. A 1H n.m.r. study of NH signals in dimethyl sulphoxide solution

1H n.m.r. spectra in [2H6]dimethyl sulphoxide of dodecyltrimethylammonium salts of chondroitin sulphates and hyaluronate, or sodium salts of oligomers from hyaluronate, showed unambiguous NH signals. The acetamido NH occurs in two different environments: environment I ('normal') in simple sugars, and environment II (hydrogen-bonded NH) appearing in tri- or tetrasaccharides, indicating a secondary structure in hyaluronate (and some chondroitin sulphates) involving a hydrogen-bonded acetamido NH.

1H nuclear-magnetic-resonance spectra of the methyl group of the acetamido moiety and the structure of acid glycosaminoglycans in solution

The 1H resonances of the methyl group in the acetamido moiety of several types of glycosaminoglycans are reported at 300 MHz in 2H2O. Dermatan sulphates with various L-iduronate/D-glucuronate ratios are compared with chrondroitin sulphates with various contents and positions of substitution of sulphate esters. Hyaluronate oligomers are compared with 2-acetamido-2-deoxy-D-glucose, and with heparan sulphate and keratan sulphate. The major determinant of the chemical shift of the acetamido methyl resonance is the closeness of approach between carboxy groups and the acetamido group, in agreement with chemical evidence based on periodate-oxidation kinetics.