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T Jefferson

Publications and source records attributed to T Jefferson.

At least 55 records · Page 3Linked to original sources
PubMed1998

Methodological quality of economic modelling studies. A case study with hepatitis B vaccines.

The notable increase in the quantity of economic evaluations in the last 2 decades has not been matched by good methodological standards. This problem is particularly evident in the field of economic evaluations of hepatitis B vaccines. The results of 2 systematic reviews conducted by us in 1993 and 1996 showed three problem areas. A sizeable minority of study reports failed to provide a clear study aim, showing a basic ignorance of the first rule of conducting scientific research. The basic epidemiological assumptions upon which the economic models were based showed variability which persisted even after stratification, raising the question of the accuracy of the epidemiological knowledge base of hepatitis B infection and its progression. Lastly, many of the studies showed weaknesses in basic methods of conducting and reporting economic evaluations. Examination of these problem areas led us to conclude that no conclusions about the efficiency of hepatitis B vaccines could be drawn from the available evidence. Addressing the problem of poor methodological standards concerns the whole research community. However, as a proportion of economic evaluations are published, one obvious means of exerting pressure to increase and maintain methodological standards is the editorial and peer review process. Editors of specialist and general medical journals should agree on and enforce common explicit guidelines for study conduct and reporting, following the example of the British Medical Journal.

Hepatitis B↗
PubMed1997

The risk society in an age of anxiety: situating fear of crime.

As many now recognize, fear of crime is an inadequately theorized concept. In particular, it is premissed on rational, calculating individuals who routinely miscalculate their 'true' risk of crime. Hence the repeatedly found paradox that the least at risk group (elderly females) are most fearful. The risk literature has adopted a cultural/anthropological rather than an individual perspective, but, in so doing has not succeeded in retheorizing the notion of the rationally calculating subject it critiques (Douglas), even if rational calculations are no longer possible in today's 'risk society' (Beck). We develop these cultural perspectives in a way which is founded on a post-structuralist theory of individuals wherein inter-subjective defending against anxiety replaces rational calculation as central to the understanding of fear. Not only does this re-link the concepts of fear and anxiety, currently divorced in the fear of crime debate, but it offers the prospect of understanding the paradoxical mismatch between risk and fear at both the level of the individual and of society.

Adolescent↗
PubMed1996

The quest for trials on the efficacy of human vaccines. Results of the handsearch of Vaccine.

We report the results of the handsearch of all the issues of Vaccine from 1983 to 1994 to identify randomized and controlled clinical trials (RCTs and CCTs) with the aim of setting up a Cochrane data base of vaccine trials. We read 1119 original papers and located 231 trials of which 117 (50.6%) were RCTs and 114 (49.4%) were CCTs. This compared with a MEDLINE search yield of only 60 trials (25.9% of reports identified by handsearching). Hepatitis B vaccine was the most popular topic (25.5% of trial reports), followed by influenza (13.4% of trial reports) and Hepatitis A (10.4% of trial reports). Seventy per cent of trials had been carried out in Europe or North America and mean overall trial size was 1136 patients (median 110). Overall only 20 trial reports mentioned placebo explicitly, while 22 reports contained data on both overall and arm size which could not be reconciled. Reviewers of vaccine trials should not base searches exclusively on MEDLINE as they are likely to miss up to 75% of trial reports. Vaccine should adopt a standardized format of reporting of trials and contributors should conform to these rules.

Controlled Clinical Trials as Topic↗
PubMed1996

Economic evaluation of influenza vaccination and economic modelling. Can results be pooled?

Scientific reviewing methods were applied to economic studies of influenza vaccination, and an economic model of influenza vaccination was developed from these primary sources. Issues arising from the secondary literature review include the quality of evidence on the effectiveness of the vaccines, the absence of a traditional population-based approach to reviewing economic data, confusion in terminology, and how to generalise from resource data contained in primary evaluations. Data from the literature review were summarised in terms of resource units used in the prevention and treatment of influenza. An economic model was constructed using local unit costs (from the Emilia region of Italy) and applying the data to a notional population. The model was sensitive to length of stay in hospital but not to variation in incidence of influenza, days off work or number of medical consultations. The model was predicated on and is sensitive to an estimate of 80% vaccine effectiveness. The approach is constrained by the available data, but could be more generally useful in that it allows variations in the quantity of inputs to be considered separately from variations in their values. The model may be used locally as a decision-making tool, although the method needs further development.

Humans↗
PubMed1994

An economic evaluation of the introduction of vaccination against hepatitis A in a peacekeeping operation. The case of the United Nations Protection Force in Yugoslavia.

The costs and benefits of vaccinating troops on United Nations tours in Yugoslavia against hepatitis A were compared. The marginal cost of one case of hepatitis A avoided by vaccination was calculated and compared with the marginal cost of achieving the same outcome by passive immunization. The cost-benefit ratio (medium estimate) for troops at low risk of contracting hepatitis A was 0.01 and for those at high risk was 0.03. Vaccinating troops against hepatitis A for a single deployment appears to be an inefficient procedure, especially in troops at low risk. However, in professional troops from countries of low hepatitis A endemicity who are likely to be involved in several operational deployments, vaccination becomes more efficient the more times the same troops are deployed.

Cost-Benefit Analysis↗
PubMed1984

Findings on a relationship between type A behavior and headaches.

Based on answers to a headache questionnaire college women were classified on a two-dimensional array according to their relative frequencies of both vascular (migraine) and tension (muscle contraction) pain. The various groups were then compared on a measure of the coronary-prone Type A behavior pattern. In two independent surveys, one with 237 respondents and one with 206 respondents, increasing frequencies of both types of headaches were significantly associated with higher scores on the Type A scale from the Jenkins Activity Survey. The findings support prior data from a client population, also reported, and suggest appropriate therapeutic interventions for headache relief. They also clearly show that a behavior pattern which has been associated with coronary artery disease now can be considered to have implications for other problems as well.

Coronary Disease↗
PubMedDate not supplied

An exercise on the feasibility of carrying out secondary economic analyses.

Purchasers of health services need up to date information on cost-effectiveness of interventions to help in prioritising spending. But economists have not yet developed a formal methodology for reviewing and summing up evidence from individual economic evaluations which may have been conducted at different times and in different places, or indeed for assessing whether such systematic reviews are possible in this context. This paper discusses the problems of reviewing available economic information, using a body of literature on the economics of influenza vaccination to illustrate some relevant issues. First, the paper examines alternative methods for adjusting prices to take into account differences in currency and time periods: Retail Price Indices are compared with health specific inflation indices, and exchange rates are compared with Purchasing Power Parity (PPP) data. For the studies reviewed, the choice of conversion method made little practical difference. Secondly, the paper explores the possibility of summarising the results of a review in terms of quantities of resources used, rather than prices. This method is constrained by the available data, but could be more generally useful as it allows direct comparison of underlying technologies, and calculation of costs by attaching local unit costs to the resources associated with an intervention. These two exercises highlight many of the problems that arise in generalising from economic studies. Both methods need to be developed further if they are to be useful to decision makers.

Cost-Benefit Analysis↗
PubMedDate not supplied

Is vaccination against hepatitis B efficient? A review of world literature.

We report on the result of a study aimed at assessing the variability of assumptions upon which economic models for the introduction of vaccination against Hepatitis B are based, the conclusions reached and define a minimum set of methodological standards upon which future economic studies on vaccines should be based. We identified 116 published and unpublished works by Medline literature searches, consulting private databases and corresponding with all authors and researchers active in economic evaluation of vaccines. All works were assessed but we included in our review only those which were original economic analyses (90 studies). Principal epidemiological and economic variables were extracted and compared where possible. Rough manipulations were carried out to make the data comparable. We found profound variability on the main parameters of the efficiency equation (disease incidence, costing methods, use of marginal theory, discounting and study time-span, sensitivity analysis and reporting methods). We also found inconsistencies in definition and study design in 38% of a subset of studies. Although we found scarce decision-making impact, we believe that due to uncertain or unclear methodology, few studies reach valid conclusions. In future decisions may be based on biased evidence and scarce resources committed to untested programmes. There is an urgent need to standardise study methods and define a common set of procedures.

Cost-Benefit Analysis↗