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Biomedical subjects

Simon Dixon

Publications and source records attributed to Simon Dixon.

At least 19 recordsLinked to original sources
PubMed2006

Percutaneous ex-vivo femoral arterial bypass: a novel approach for treatment of acute limb ischemia as a complication of femoral arterial catheterization.

This report describes the use of a percutaneous ex-vivo femoral arterial bypass in three patients with acute lower extremity ischemia that occurred as a complication of femoral artery catheterization. Utilizing standard equipment and techniques, a percutaneous ex-vivo femoral artery bypass can restore antegrade flow to the ischemic limb in patients with impaired aorto-iliac inflow circulation, which may arise from iatrogenic dissection or the need for large in-dwelling sheaths required for hemodynamic support. This technique is considered a temporizing measure when conventional therapies are not possible. Contrast angiography is recommended to localize and define the cause of limb ischemia, and to permit safe placement of vascular sheaths in the "donor and recipient" arteries.

Acute Disease↗
PubMed2006

Impact of cognitive behavior therapy on health-related quality of life among adult hypnotic users with chronic insomnia.

Results were combined from representative surveys of health related quality of life (HRQoL; n=11,877; age range=16-104) with data from a randomized controlled trial of cognitive behavior therapy for chronic insomnia (n=209; age range=31-92). Secondary analyses of scores from the SF-36 measure of HRQoL were conducted in order: (a) to compare the health related quality of life profiles of adult hypnotic users with chronic insomnia with those of population norms, and (b) to assess the impact of cognitive behavior therapy (CBT) for insomnia on HRQoL outcomes over 6 months. Compared with the primary care reference values, HRQoL among the trial participants at baseline was generally poorer. The magnitude of these decrements reduced markedly with advancing age. In the evaluation of the CBT intervention, statistically significant differences in SF-36 scores in favor of the intervention were present for physical functioning, emotional role limitation, and mental health over 6 months. Overall, this study shows that the SF-36 can play an important role in describing HRQoL in this patient group, and in the evaluation of interventions within this group.

Adolescent↗
PubMed2006

Incorporating carer effects into economic evaluation.

BACKGROUND: Despite great interest in the development of methods used in the economic evaluation of health technologies, the effects of carer costs and quality of life (QOL) on the cost effectiveness of treatments has not been widely explored. Yet carer effects are clearly evident in the literature and relevant to the perspective of many published economic evaluations. OBJECTIVE: To examine whether patient QOL is associated with carer time and carer QOL. METHODS: We used two datasets to investigate carer effects. Firstly, we used 40,312 cases from the Health Outcomes Data Repository (HODaR) to assess the relationship between patient utility, using the EuroQoL (EQ)-5D, and the number of days care needed from friends and relatives. The stability of the relationship across patient subgroups was assessed by replicating the analysis in ten disease groups. Secondly, we used 64 cases from a study of patients with Alzheimer's disease and their primary carer. These data allowed us to estimate the relationships between patient and carer utility, using the EQ-5D, and patient utility and carer burden using the Community Dementia Quality of Life Profile (CDQLP). RESULTS: For carer time, a linear model showed that each 0.1-point reduction in patient utility was associated with a 2.5-day increase in carer time over a 6-week period. A more general model, based on EQ-5D domain scores, was better specified and showed that decreased functioning within each domain is associated with increased carer time. Problems with self-care and usual activities have the greatest impact on carer time. These models do not appear to be stable across different disease groups. For carer utility, the relationships between carer and patient utility have low explanatory power and are poorly specified. A clearer relationship is shown between carer burden and utility, such that when sociodemographic covariates are introduced, the relationship reaches conventional levels of statistical significance (p < 0.05). CONCLUSIONS: The preliminary work described here shows that improving patient QOL may reduce the need for carer time and improve carer QOL. Incorporating such effects into economic evaluations will change cost-per-QALY estimates, with the size of reduction dependent on the domains of health affected by treatment. Clinical studies need to capture carer data so that we can better understand these effects, and how they impact on economic evaluation.

Activities of Daily Living↗
PubMed2006

Evaluation of the cost effectiveness of sirolimus versus tacrolimus for immunosuppression following renal transplantation in the UK.

INTRODUCTION: Immunosuppressive therapy is required to prevent graft rejection. Calcineurin inhibitors such as tacrolimus are paradoxically toxic to the kidney, whereas sirolimus (rapamycin; Rapamune) is not generally associated with the nephrotoxicity of CNIs. The purpose of this study was to evaluate the relative cost utility of sirolimus versus tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK. METHODS: A stochastic simulation model was constructed using clinical trial and observational data comparing the two treatments. Time duration was up to 20 years. Costs were from a UK NHS perspective, valued at 2003 prices and discounted at 6%. Benefits were discounted at 1.5%. Simulated events included patient and graft survival, haemodialysis, peritoneal dialysis, re-transplants and acute rejection. Costs were summed for events and various maintenance therapies. Utility was differentially accredited depending upon survival and using the alternative renal replacement therapies. Outcome was predicted using post-transplant creatinine levels up to 3 years. Extensive statistical economic and sensitivity analyses were undertaken. RESULTS: Over the 10-year horizon, sirolimus gained 0.72 years (discounted) of functioning graft over tacrolimus, resulting in an incremental cost per year of functioning graft that was dominant. Over a 20-year time horizon, the cost effectiveness of sirolimus over tacrolimus further improved with an average discounted gain in years of a functioning graft of 1.8 years, resulting in an incremental cost-utility ratio that was also dominant. The number of haemodialysis events was 48,243 for sirolimus recipients versus 127,829 for those receiving tacrolimus and peritoneal dialysis events 40,872 versus 105,249, respectively. Similar values were obtained when real-life observational data on tacrolimus use in Cardiff, Wales were entered into the model. Using data from Cardiff, sirolimus remained dominant over tacrolimus under all scenarios. CONCLUSION: Our study suggests that sirolimus may be more cost effective than tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK. Sirolimus was economically 'dominant' under almost all scenarios investigated. This finding was robust using statistical economic analysis and univariate sensitivity analysis.

Adult↗
PubMed2005

Advanced access: more than just GP waiting times?

BACKGROUND: Advanced access has been forwarded as a strategy for reducing waiting times in primary care; however, previous evaluations have raised important issues regarding its appropriateness. OBJECTIVES: The objectives of this paper are to assess the impact of advanced access on patient access to primary care services, and its broader effects on stakeholders. METHODS: A quantitative analysis of appointment data on 462 practices implementing advanced access, together with qualitative analysis of open survey responses and interviews with 28 practice staff. Appointment data recorded time to third available appointment for GP and practice nurse, together with the percentage of patients seen on their day of choice. Themes were identified from the interviews and survey responses and related to issues identified in previous research. RESULTS: The implementation of advanced access was associated with reductions in time to see practice nurses as well as GPs, and increases in the proportion of patients being seen on their day of choice. Interviewee and survey responses suggested that practice population characteristics may impact on the model, and some patient groups may be disadvantaged from the changes in the appointment systems seen in this study. Whilst experiences were mixed, the potential for broader changes to working practices of all practice staff was evident. CONCLUSIONS: In general, these results suggest that advanced access can have a positive impact across several aspects of primary care services, and not just the availability of GP appointments. However, it also highlights some problems, in that waiting times worsened in some practices and there were concerns that some vulnerable groups may be disadvantaged.

Appointments and Schedules↗
PubMed2005

Incidence and prognostic impact of gastrointestinal bleeding after percutaneous coronary intervention for acute myocardial infarction.

We examined the incidence, presentation, and outcome of patients who developed gastrointestinal bleeding after percutaneous coronary intervention for acute myocardial infarction in the Primary Angioplasty in Myocardial Infarction trials. Of the 3,130 patients, 71 (2.3%) developed gastrointestinal bleeding, which was more likely to occur in elderly patients. Gastrointestinal bleeding was independently associated with a prolonged hospital stay and greater in-hospital and 6-month mortality.

Age Distribution↗
PubMed2005

Parametric modelling of cost data: some simulation evidence.

Recently, commentators have suggested that the distributional form of cost data should be explicitly modelled to gain efficiency in estimating the population mean. We perform a series of simulation experiments to evaluate the usual sample mean and the mean estimator of a lognormal distribution, in the context of both theoretical distributions and three large empirical datasets. The sample mean is always unbiased, but is somewhat less efficient when the population distribution is truly lognormal. However the lognormal estimator can perform appallingly when the true distribution is not lognormal. In practical situations, where the true distribution is unknown, the sample mean generally remains the estimator of choice, especially when limited sample size prohibits detailed modelling of the cost data distribution.

Clinical Trials as Topic↗
PubMed2005

The financial costs of hospital care for people with diabetes who have single and multiple macrovascular complications.

AIM: To evaluate the impact on hospital costs of patients being diagnosed with multiple complications of diabetes. METHODS: All inpatient admissions and outpatient appointments from the Cardiff and Vale of Glamorgan area (1996 onwards) were cross-referenced to the diabetes register. Each episode of inpatient care was coded using Healthcare Resource Group (HRG) grouper software. The allocated HRG-coded episode was linked to a series of elective and emergency reference costs from the National Health Service costing manual. Outpatient appointments were cost-coded using the mean reference costs by specialty. Non-psychiatric finished consultant episodes (FCEs) were used rather than admissions to report inpatient utilisation. RESULTS: Overall, 2815 of the total 10,287 patients identified as inpatients had at least one admission; 6133 admissions (finished consultant episodes) were successfully grouped to give a total estimated cost of pound sterling 7,373,539. An incremental, linear relationship was observed in the cost increases for each additional diagnosed complication. Mean annual inpatient age-standardised costs were pound sterling 434 for no complications, pound sterling 999 for one complication, pound sterling 1,641 for two, and pound sterling 2,462 for three. There were 5717 patients with diabetes who attended 25,334 outpatient appointments. The estimated cost for these outpatient appointments was pound sterling 1,833,232. CONCLUSION: Minimising the number of complications in patients with diabetes would result in considerable cost offsets.

Ambulatory Care↗
PubMed2005

Patterns of graft and patient survival following renal transplantation and evaluation of serum creatinine as a predictor of survival: a review of data collected from one clinical centre over 34 years.

BACKGROUND: The pattern of renal transplantation has never been described since the introduction of the technique. The purpose of this study was therefore to characterise the pattern of renal transplantation from 1967 to 2000, focusing on renal graft function as a predictor of survival. METHODS: This study was a retrospective analysis of an electronic database. The setting was a single renal transplant centre in the United Kingdom covering a population of 2.2 million and included patients who received at least one renal transplant over the study period (n = 1516). The main outcome measures were patient and graft survival, acute rejection episodes and patterns of graft function, as measure by creatinine levels. RESULTS: There were 559 (36.8%) female patients; 109 (7.2%) patients had pre-existing diabetes. Patient survival was adversely affected by increased age at transplant (p < 0.001): 5-year patient survival from first transplant was 82% for patients aged 0 to 17 years, 80% for 18 to 49 years and 61% for > 49 years. Pre-existing diabetes also adversely affected survival (p < 0.01): 5-year graft survival was 63% for patients with diabetes versus 74% for those without. Graft survival was significantly associated with serum creatinine levels recorded 1 year post-primary transplant (p < 0.001) and with three or more acute rejection episodes (p < 0.05). Neither gender nor diabetes status were statistically significant in predicting graft survival. The number of acute rejection episodes was significantly greater in patients with pre-existing diabetes than those without (61% versus 42%, respectively; p < 0.001). There were no differences in the number of acute rejection episodes occurring across age groups. CONCLUSION: Patient and graft survival improved markedly over the 34-year study period, although patient survival has changed little since 1990. Serum creatinine levels are a reliable predictor of graft survival.

Adolescent↗
PubMed2005

Economic analysis of the implementation of autologous transfusion technologies throughout England.

OBJECTIVES: This study aims to provide the first estimates of the costs and effects of the large scale introduction of autologous transfusion technologies into the United Kingdom National Health Service. METHODS: A model was constructed to allow disparate data sources to be combined to produce estimates of the scale, costs, and effects of introducing four interventions. The interventions considered were preparing patients for surgery (PPS) clinics, preoperative autologous donation (PAD), intraoperative cell salvage (ICS), and postoperative cell salvage (PoCS). RESULTS: The key determinants of cost per operation are the anticipated level of reductions in blood use, the mean level of blood use, mean length of stay, and the cost of the technology. The results show the potential for considerable reductions in blood use. The greatest reductions are anticipated to be through the use of PPS and ICS. Vascular surgery, transplant surgery, and cardiothoracic surgery appear to be the specialties that will benefit most from the technologies. CONCLUSIONS: Several simplifications were used in the production of these estimates; consequently, caution should be used in their interpretation and use. Despite the drawbacks in the methods used in the study, the model shows the scale of the issue, the importance of gathering better data, and the form that data must take. Such preliminary modeling exercises are essential for rational policy development and to direct future research and discussion among stakeholders.

Blood Loss, Surgical↗
PubMed2004

Frequency of returning to work one and six months following percutaneous coronary intervention for acute myocardial infarction.

We conducted an analysis of the frequency and variables associated with early (after 1 month) and late (after 6 months) return to work after percutaneous coronary intervention for acute myocardial infarction in patients who had been randomized in the Stent Primary Angioplasty in Myocardial Infarction trial. Of 450 patients who were employed before the acute myocardial infarction, 230 (51%) returned to work within 1 month with no increases in in-hospital and 1- or 6-month event rates compared with those who did not return to work. Multivariate analysis showed that predictors of early return to work were employment in the United States, no history of smoking, and single-vessel coronary disease. At 6 months, 353 of 435 patients (78%) had returned to work, and multivariate analysis showed that predictors of late return to work were employment in the United States and absence of angina.

Absenteeism↗
PubMed2004

Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care.

OBJECTIVES: To measure the effectiveness and cost effectiveness of providing care in a chest pain observation unit compared with routine care for patients with acute, undifferentiated chest pain. DESIGN: Cluster randomised controlled trial, with 442 days randomised to the chest pain observation unit or routine care, and cost effectiveness analysis from a health service costing perspective. SETTING: The emergency department at the Northern General Hospital, Sheffield, United Kingdom. PARTICIPANTS: 972 patients with acute, undifferentiated chest pain (479 attending on days when care was delivered in the chest pain observation unit, 493 on days of routine care) followed up until six months after initial attendance. MAIN OUTCOME MEASURES: The proportion of participants admitted to hospital, the proportion with acute coronary syndrome sent home inappropriately, major adverse cardiac events over six months, health utility, hospital reattendance and readmission, and costs per patient to the health service. RESULTS: Use of a chest pain observation unit reduced the proportion of patients admitted from 54% to 37% (difference 17%, odds ratio 0.50, 95% confidence interval 0.39 to 0.65, P < 0.001) and the proportion discharged with acute coronary syndrome from 14% to 6% (8%, -7% to 23%, P = 0.264). Rates of cardiac event were unchanged. Care in the chest pain observation unit was associated with improved health utility during follow up (0.0137 quality adjusted life years gained, 95% confidence interval 0.0030 to 0.0254, P = 0.022) and a saving of pound 78 per patient (- pound 56 to pound 210, P = 0.252). CONCLUSIONS: Care in a chest pain observation unit can improve outcomes and may reduce costs to the health service. It seems to be more effective and more cost effective than routine care.

Algorithms↗
PubMed2004

Comparative estimates of the financial burden to the UK health system of hospital care for people with and without diabetes in the year before death.

OBJECTIVE: To quantify hospital costs prior to death for patients with and without diabetes. RESEARCH DESIGN AND METHODS: Using the Cardiff Diabetes Database, mortality data from the UK Office of National Statistics for 1996 were linked to existing hospital records using probability matching techniques. Costs were attributed using a statistical costing technique (healthcare resource groups (HRGs)) with UK 2000 prices. RESULTS: There were 4394 deaths of which 412 (9.4%) were for patients with diabetes. In the year before death 380 (92%) patients with diabetes (DM+) were admitted as an inpatient compared with 73% of those without diabetes (DM-), a relative rate of 1.27. Total inpatient costs were 12.2M UK pound sterling (20M US dollars) of which costs for patients with diabetes were 1.6M UK pound sterling (2.6M US dollars), accounting for 15.6% of revenue. This translates to a rate of 2.8M UK pound sterling (4.0M US dollars) per 100,000 population per year. The mean annual inpatient cost before death was UK pound 3997 (5676 US dollars) for DM+ compared with UK pound 2656 (3772 US dollars) for DM-. Mean annual outpatient costs ranged from 185 UK pound sterling (263 US dollars: year minus 4) to 248 UK pound sterling (352 US dollars: year minus 2) in DM+, and 91 UK pound sterling (129 US dollars: year minus 4) to 116 UK pound sterling (165 US dollars: year minus 2) in DM-. Mean annual outpatient costs associated with the care of people with diabetes are consistently higher: +80% at minus 1-year rising to +120% at minus 3 years. CONCLUSIONS: The costs of inpatient care for all patients increases markedly in the final year of life. People with diabetes were found to be more financially costly, even in this stage of their care, than were people who did not have diabetes.

Diabetes Mellitus↗
PubMed2004

Economic evaluations of treatments for systemic fungal infections: a systematic review of the literature.

We systematically reviewed published economic evaluations of systemic antifungal therapies and assessed their strengths and weaknesses. The study identified all economic evaluations published before May 2002 and critically appraised their methods using a published checklist. Over 1000 papers on antifungal treatments and costs were retrieved, 40 of which were economic evaluations. Fifteen of these were evaluations of systemic antifungal therapy. The majority of studies examined prophylaxis (11 out of 15), two examined empiric treatment and two examined the treatment of confirmed infections. Methods varied quite dramatically and the quality of the studies was, in general, very poor. Consequently, we were unable to find a coherent body of economic evidence for any particular patient group and/or indication. Three methodological issues were identified as requiring improvement in future economic evaluations of the prevention and treatment of systemic mucoses: cost estimates, outcome measures and evidence of effectiveness. Costs of both antifungal infection and treatment are important, and despite this, seven of the studies only collected cost information on drug acquisition costs. This is such a fundamental flaw that these studies should not be used to inform decision making on the use of antifungal medication. The estimation of costs in the other studies appeared appropriate, although limited reporting obscured other important issues, such as the appropriate use of per diem costs. Outcome measures were necessarily produced in all evaluations, yet only two studies produced cost-effectiveness ratios. This makes comparisons across studies very difficult. Also, small samples sizes meant that 'hard' outcome measures such as life-years saved could not be used, as deaths were rare within the studies. Both studies that produced incremental cost-effectiveness ratios were model-based studies. These allow simulations to be run on large cohorts of hypothetical patients, thus allowing differences in mortality between treatments to be evaluated. Evidence of effectiveness was limited, with many of the studies based on non-randomised clinical studies and consequently open to bias. Future clinical trials of the effectiveness of antifungal prophylaxis and treatment need to incorporate the collection of costs and economic outcome measures. Even quite simple analyses can be quite powerful, particularly when combined with modelling work to allow other data sources to be added.

Antifungal Agents↗
PubMed2004

Evaluation of advanced access in the national primary care collaborative.

BACKGROUND: An aim of the National Primary Care Collaborative is to improve quality and access for patients in primary care using principles of Advanced Access. AIMS: To determine whether Advanced Access led to improved availability of appointments with general practitioners (GPs) and to examine GPs' views of the process. DESIGN: Observational study. SETTING: Four hundred and sixty-two general practices in England participating in four waves of the collaborative during 2000 and 2001. METHOD: Regression analysis of the collaborative's monthly data on the availability of GP appointments for the 352 practices in waves 1-3, and a postal survey of lead GPs in all four waves. The main outcome measures were the change in mean time to the third available appointment with GPs, and the proportion of GPs thinking it worthwhile participating in the collaborative. RESULTS: The time to the third available appointment improved from a mean of 3.6 to 1.9 days, difference = 1.7 days, 95% confidence interval (CI)= 1.4 to 2.0 days. It improved in two-thirds of practices (66% [219/331]), remained the same in 16% (53/331), and worsened in 18% (59/331). The majority of GPs in all four waves, 83% (308/371, 95% CI = 79 to 87), felt that it was worthwhile participating in the collaborative, although one in 12 practices would not recommend it. One-fifth of GPs cited a lack of resources as a constraint, and some expressed concerns about the trade-off between immediate access and continuity of care. CONCLUSION: Advanced Access helped practices to improve availability of GP appointments, and was well received by the majority of practices.

Appointments and Schedules↗
PubMed2003

Predicting longer-term outcomes following psychological treatment for hypnotic-dependent chronic insomnia.

OBJECTIVES: To identify predictors of treatment adherence, patient dropout, and treatment response among long-term hypnotic users recruited into a randomized controlled trial of psychological treatment for insomnia. METHODS: Of 108 treatment and 101 control patients initially recruited, 37 treatment group patients (34.3%) failed to complete all 6 sessions (i.e., were nonadherent), while across both groups 61 (29.2%) patients failed to return postal assessments at 3-month follow-up (i.e., dropped out). Relationships between baseline characteristics and adherence (adherent vs. nonadherent) and attrition (dropout vs. nondropout) were examined in discriminant models. Relationships between baseline characteristics and treatment response (sleep quality, sleep latency, sleep efficiency, and hypnotic drug use) were examined in a series of multiple regression models. RESULTS: Adherent patients showed a significantly greater severity of pretreatment sleep disturbance, as measured by the Pittsburgh Sleep Quality Index (PSQI). Dropout at 3 months was associated with significantly lower perceived health status at baseline. In the regression models, lower Cure/Control subscale scores from the Illness Perception Questionnaire (IPQ) predicted greater posttreatment improvements in sleep efficiency and PSQI scores, while lower baseline anxiety scores predicted a posttreatment increase in hypnotic-free nights/week. CONCLUSION: In routine clinical practice settings, higher anxiety and a less positive attitude towards symptom control were associated with poorer treatment response. Adherence and attrition show a different pattern of associations, with greater need (as indexed by insomnia severity) predicting higher levels of service uptake and poorer general health predicting a higher likelihood of dropout.

Adult↗