Paul Fenn

A model to estimate the lifetime health outcomes of patients with type 2 diabetes: the United Kingdom Prospective Diabetes Study (UKPDS) Outcomes Model (UKPDS no. 68).

Aims/hypothesisThe aim of this study was to develop a simulation model for Type 2 diabetes that can be used to estimate the likely occurrence of major diabetes-related complications over a lifetime, in order to calculate health economic outcomes such as quality-adjusted life expectancy.MethodsEquations for forecasting the occurrence of seven diabetes-related complications and death were estimated using data on 3642 patients from the United Kingdom Prospective Diabetes Study (UKPDS). After examining the internal validity, the UKPDS Outcomes Model was used to simulate the mean difference in expected quality-adjusted life years between the UKPDS regimens of intensive and conventional blood glucose control.ResultsThe model’s forecasts fell within the 95% confidence interval for the occurrence of observed events during the UKPDS follow-up period. When the model was used to simulate event history over patients’ lifetimes, those treated with a regimen of conventional glucose control could expect 16.35 undiscounted quality-adjusted life years, and those receiving treatment with intensive glucose control could expect 16.62 quality-adjusted life years, a difference of 0.27 (95% CI: −0.48 to 1.03).Conclusions/interpretationsThe UKPDS Outcomes Model is able to simulate event histories that closely match observed outcomes in the UKPDS and that can be extrapolated over patients’ lifetimes. Its validity in estimating outcomes in other groups of patients, however, remains to be evaluated. The model allows simulation of a range of long-term outcomes, which should assist in informing future economic evaluations of interventions in Type 2 diabetes.

Confidence intervals or surfaces? Uncertainty on the cost-effectiveness plane

Although cost-effectiveness analysis is not new, it is only recently that economic analysis has been conducted alongside clinical trials. Whereas in the past economic analysts most often used sensitivity analysis to examine the implications of uncertainty for their results, the existence of patient-level data on costs and effects opens up the possibility of statistical analysis of uncertainty. Unfortunately, ratio statistics can cause problems for standard statistical methods of confidence interval estimation. The recent health economics literature contains a number of suggestions for estimating confidence limits for ratios. In this paper, we begin by reviewing the different methods of confidence interval estimation with a view to providing guidance concerning the most appropriate method. We go on to argue that the focus on confidence interval estimation for cost-effectiveness ratios in the recent literature has been concerned more with problems of estimation than with problems of decision-making. We argue that decision-makers are most likely to be interested in one-sided tests of hypothesis and that confidence surfaces are better suited to such tests than confidence intervals. This approach is consistent with decision-making on the cost-effectiveness plane and with the cost-effectiveness acceptability curve approach to presenting uncertainty due to sampling variation in stochastic cost-effectiveness analyses.

Cost effectiveness of an intensive blood glucose control policy in patients with type 2 diabetes: economic analysis alongside randomised controlled trial (UKPDS 41)

Abstract Objective: To estimate the cost effectiveness of conventional versus intensive blood glucose control in patients with type 2 diabetes. Design: Incremental cost effectiveness analysis alongside randomised controlled trial. Setting: 23 UK hospital clinic based study centres. Participants: 3867 patients with newly diagnosed type 2 diabetes (mean age 53 years). Interventions: Conventional (primarily diet) glucose control policy versus intensive control policy with a sulphonylurea or insulin. Main outcome measures: Incremental cost per event-free year gained within the trial period. Results: Intensive glucose control increased trial treatment costs by £695 (95% confidence interval £555 to £836) per patient but reduced the cost of complications by £957 (£233 to £1681) compared with conventional management. If standard practice visit patterns were assumed rather than trial conditions, the incremental cost of intensive management was £478 (-£275 to £1232) per patient. The within trial event-free time gained in the intensive group was 0.60 (0.12 to 1.10) years and the lifetime gain 1.14 (0.69 to 1.61) years. The incremental cost per event-free year gained was £1166 (costs and effects discounted at 6% a year) and £563 (costs discounted at 6% a year and effects not discounted). Conclusions: Intensive blood glucose control in patients with type 2 diabetes significantly increased treatment costs but substantially reduced the cost of complications and increased the time free of complications.

Estimating long-term cost savings from treatment of Alzheimer's disease. A modelling approach.

AbstractObjective: This paper puts forward a proposal for a modelling approach to the estimation of long term cost savings from the treatment of Alzheimer’s disease(AD). Design: In the proposed modelling approach, disease progression is defined in terms of intervals in the Mini-Mental State Exam (MMSE) scale. Clinical trial data are then used to determine the time at which a particular patient moved into amore severe stage of the disease. By comparing these durations across treatment groups, survival analysis is used to measure the impact of treatment in delaying the onset of a more costly stage of the disease. Setting: Patients with varying severity of AD. Patients and participants: The model uses clinical trial data on 1333 patients recruited internationally in 2 studies from 67 centres. Interventions: The aim of these clinical studies was to evaluate the safety and efficacy of 2 non-overlapping dose ranges of rivastigmine relative to placebo over a 26-week treatment period in patients with probable AD. Main outcome measures and results: The results indicate that the average cost savings with high-dose rivastigmine at the end of the trial period are quite low (approximately £29 per patient; 1997 values), but by extrapolating to a projected lifetime of 3 years, they rise to approximately £1100 per patient. The largest long term cost savings from treatment are obtained from treating those in the mild category (i.e. MMSE > 20). However, if the time horizon over which savings are estimated is short (i.e. if life expectancy is below 2 years), more costs are saved by prioritising patients with moderate AD (i.e. MMSE between 20 and 11). Conclusions: The model is a possible approach for estimating cost savings with treatment of AD, given the lack of long term data on resource use and drug efficacy. Caution should be used when extrapolating the results beyond the original study parameters.

The cost of insulin-dependent diabetes mellitus (IDDM) in England and Wales.

This study estimates the direct health and social care costs of insulin‐dependent diabetes mellitus (IDDM) in England and Wales in 1992 to be £96 million, or £1021 per person in a population with IDDM estimated at 94 000 individuals. These costs include insulin maintenance, hospitalization, GP and out‐patient consultations, renal replacement therapy, and payments to informal carers. Expenditure is concentrated on younger age groups, with one‐third of the total expended on those aged 0–24. Around one‐half of the total costs can be directly attributed to IDDM, with the remainder associated with a range of complications of the disease. The single largest area of service expenditure is renal replacement therapy. The cost estimates are most sensitive to incidence rates of IDDM, numbers on dialysis and average duration of dialysis. A further £113 million pounds may be lost each year due to premature deaths resulting in lost productive contributions to the economy. The direct and indirect costs of IDDM are therefore significant. The cost of illness framework presented here should facilitate the economic evaluation of new and existing treatment regimens, which may improve value for money by reducing costs and/or increasing the quality or quantity of life for people with IDDM.

Compensation and support for illness and injury

Reporting the findings of a large national survey in the United Kingdom, this study examines different systems of compensation and support for the injured, ill, or congenitally handicapped and their families. The authors assess the roles of government agencies, local authorities, employers, and informal organizations in providing such services as social security, criminal injuries compensation, sick pay, and private insurance. The work will be of interest to lawyers, government officials, social security officers, and all others working with people seeking compensation for accident and injury.

Current cost of medical negligence in NHS hospitals: analysis of claims database

Abstract Objectives: To identify trends in the incidence and cost of clinical negligence claims. To determine the current annual cost to the NHS as a whole in terms of cash paid out to patients and their solicitors and the defence costs incurred. Design: Analysis of records on database. Setting: A well defined group of hospitals within one health authority which collected information on a consistent basis over many years. Main outcome measures: Data on individual claims. Trends in incidence of claims and costs identified independently from organisational reforms and changes in accounting practices. Results: The rate of litigation increased from 0.46 to 0.81 closed claims per 1000 finished consultant episodes between 1990 and 1998. Overall expenditure on clinical negligence by the NHS in England in 1998 was estimated at £84 million (95% confidenceinterval £48 million to £130 million). Conclusions: After adjustment for hospital activity, the rate of closed claims increased during the 1990s by about 7% per annum, a substantial rate of growth but not the uncontrolled explosion sometimes alluded to in the wider media. More coordinationand openness are needed in data collection.

The analysis of censored treatment cost data in economic evaluation

This article investigates the way in which the presence of censored cost data in clinical trials should dictate the inferential tests adopted when comparing treatment and nontreatment groups for the purpose of economic evaluation. The authors argue that the techniques of survival analysis are appropriate where censoring is present, and that bias will be imparted if cruder methods are used to analyze cost data, even if that data is drawn from a relevant population. The first section of the article discusses the problem of censoring and survival analysis, while the second examines three methods of dealing with censored cost data and possible biases resulting from them. The third section presents results from actual trial data using the three methods described in the preceding section. Conclusions are presented in section four, where it is argued that these methodological issues are likely to become more important as economists are called upon to evaluate the treatment of chronic conditions using data from clinical trials with finite end points.

“A respectable profession”? Sociological and economic perspectives on the regulation of professional services

There is an unresolved problem at the heart of both the economic and the sociological study of the professions. Are these occupations simple monopolies whose anticompetitive effects distort the social and economic organization of a society or are they institutions which have developed for public interest reasons and should be preserved? This paper reviews the treatment of the professions in contemporary social science. It begins by discussing the current orthodoxy, which emphasizes their anticompetitive effects, and some of its recent critics. It is argued that both of these neglect the critical role of professionalization in maintaining trust or confidence in the workings of the market under the conditions of a complex modern society. If this is accepted, then new directions are implied in both academic study and policy debate.

Judicial Independence: Some Evidence from the English Court of Appeal

This paper is concerned with the existence or otherwise of conscious political interference with judicial decision taking. We produce new evidence from the English Court of Appeal to shed some light on the theoretical debate on judicial independence. This evidence rests on the fact that the procedure for promoting judges from the Court of Appeal to the House of Lords is in principle under political control: the lord chancellor, who has a key role in the promotion of judges, is a member of the cabinet and as such a political appointee. The data relate to public law decisions made by judges in the Court of Appeal over the period 1951–86. We use a competing risks survival model to establish whether the record of individual judges in deciding for or against the government was a factor that determined their promotion chances, controlling for the quality of their decision making.