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A Briggs

Publications and source records attributed to A Briggs.

At least 37 records · Page 2Linked to original sources
PubMed1998

Examination of the two-dimensional pupil function in coherent scanning microscopes using spherical particles.

The determination of the modulus of the pupil function in reflection acoustic and optical microscopy with the help of spherical particles is demonstrated. The theoretical examination shows that this method can give good results if the pupil function drops smoothly towards the edge. For a pupil with a sharp edge this technique can give the accurate pupil function only by imaging large spheres. The dependence of the accuracy of the method on the size of the spherical particle is analyzed. Numerical and experimental results obtained for the confocal scanning optical microscope and the scanning acoustic microscope are examined.

Acoustics↗
PubMed1998

The distribution of health care costs and their statistical analysis for economic evaluation.

OBJECTIVE: Where patient level data are available on health care costs, it is natural to use statistical analysis to describe the differences in cost between alternative treatments. Health care costs are, however, commonly considered to be skewed, which could present problems for standard statistical tests. This review examines how authors report the distributional form of health care cost data and how they have analysed their results. METHOD: A review of cost-effectiveness studies that collected patient-level data on health care costs. To supplement the review, five datasets on health care costs are examined. Consideration is given to the use of parametric methods on the transformed scale and to non-parametric methods of analysing skewed cost data. RESULTS: Since economic analysis requires estimation in monetary units, the usefulness of transformation-based methods is limited by the inability to retransform cost differences to the original scale. Non-parametric rank sum methods were also found to be of limited use for economic analysis, partly due to the focus on hypothesis testing rather than estimation. Overall, the non-parametric approach of bootstrapping was found to offer a useful test of the appropriateness of parametric assumptions and an alternative method of estimation where those assumptions were found not to hold. CONCLUSIONS: Guidelines for the analysis of skewed health care cost data are offered.

Cost-Benefit Analysis↗
PubMed1998

An introduction to Markov modelling for economic evaluation.

Markov models are often employed to represent stochastic processes, that is, random processes that evolve over time. In a healthcare context, Markov models are particularly suited to modelling chronic disease. In this article, we describe the use of Markov models for economic evaluation of healthcare interventions. The intuitive way in which Markov models can handle both costs and outcomes make them a powerful tool for economic evaluation modelling. The time component of Markov models can offer advantages of standard decision tree models, particularly with respect to discounting. This paper gives a comprehensive description of Markov modelling for economic evaluation, including a discussion of the assumptions on which the type of model is based, most notably the memoryless quality of Markov models often termed the 'Markovian assumption'. A hypothetical example of a drug intervention to slow the progression of a chronic disease is employed to demonstrate the modelling technique and the possible methods of analysing Markov models are explored. Analysts should be aware of the limitations of Markov models, particularly the Markovian assumption, although the adept modeller will often find ways around this problem.

Economics, Pharmaceutical↗
PubMed1997

Analgesics: a comparison of therapeutic knowledge and inter-professional liaison between general practitioners and community pharmacists.

The aim of this study was to ascertain general practitioners' (GPs') and pharmacists' knowledge of analgesics, to establish professional opinion on their use, and to assess the extent of pharmacist input into the prescribing of analgesics. Pharmacists displayed a better knowledge of analgesics than their colleagues in general practice, but had little input into the prescribing decisions made by GPs. Pharmacists' knowledge is not being put to best use in contributing to the preparation of practice formularies, and links between these two health professional groups need to be developed further.

Analgesics↗
PubMed1996

A model for analyzing the cost of main clinical events after cardiac transplantation.

Using information from the Papworth Hospital heart transplant service, a model was developed to link the main clinical events after cardiac transplantation to survival and costs. On the basis of the clinical and survival experience of 387 patients treated with triple-drug immunosuppression between 1986 and 1993, together with protocols for patient management, resource use, and costs, a 5-year Markov model with three time periods was used to simulate survival and estimate costs. The model accurately mirrors observed actuarial survival; 1- and 5-year survival rates were 81% and 65%, respectively. An average cost per patient of 26,000 pounds over 5 years (discounted at a rate of 6%) was estimated. The expense of routine care for patients accounts for the majority of the costs; a patient who remains well throughout the 5-year period would incur costs of 23,000 pounds. The sensitivity of the estimates to alternative assumptions is presented, and the way in which the model can be used to compare alternative future scenarios is explored.

Adolescent↗
PubMed1995

Long-term follow-up after a drug trial for panic disorder.

BACKGROUND: This study investigates the naturalistic course of panic disorder over four years and attempts to identify predictors for outcome. METHOD: 423 DSM-III-R panic disorder patients who had taken part in an international multicentre drug trial were selected for follow-up; we were able to re-interview 367 (87%). For panic attacks, phobic avoidance and disabilities the same rating scales were administered as had been used for the clinical trials. RESULTS: While 61% of all patients experienced at least occasional panic attacks at follow-up, few suffered from serious phobic avoidance (16.7%) or serious disabilities (work 7.9%); family 8.7%; social 13.9%). Panic attack frequency at baseline, original trial medication and continuous use of psychotropic medication during follow-up are not related to outcome, whereas longer duration of illness and more severe phobic avoidance at baseline are unfavourable. CONCLUSION: The course of panic disorder is not uniform. Since long duration of illness and severe phobic avoidance at baseline are predictors for an unfavourable outcome, more rigorous efforts should be undertaken to detect and treat panic disorder at an early stage.

Adolescent↗
PubMed1994

The cost effectiveness of alpha interferon in the treatment of chronic active hepatitis C.

OBJECTIVE: To model the costs and effects of alpha interferon in the treatment of chronic active hepatitis C. DESIGN: A Markov modelling process to simulate the costs and outcomes in hypothetical cohorts of patients treated with and without alpha interferon. OUTCOME MEASURES: Costs per life saved and per life-year gained. RESULTS: On the basis of assumptions formulated about the disease processes and response to treatment, treatment with alpha interferon results in a discounted cost per life-year gained of $33,230 in patients with cirrhosis at the start of treatment and $71,950 in patients without advanced liver disease. The result is sensitive to the assumptions made about the long term effectiveness of alpha interferon. CONCLUSIONS: Alpha interferon is an expensive drug. Its effectiveness is clouded by uncertainty about the long term impact of the drug on the natural history of the disease. If adopted, its use should be monitored to allow the long term cost effectiveness of the drug to be evaluated properly.

Cost-Benefit Analysis↗
PubMed1979

Familial partial trisomy of the long arm of chromosome 3 (3q).

A case of partial trisomy of the long arm of chromosome 3 (3q21 leads to qter) is described. The clinical findings are compared with those in 5 previously reported cases. There is hirsutism and characteristic facial dysmorphism, the common features of which are a square-shaped face, prominent nasal bridge, everted nostrils, hypertelorism, and palate abnormalities; occurring less often are abnormalities of vertebrae, thorax, and digits, or cardiovascular, urinogenital, and central nervous system. New features noted in this present case are absence of right eye from orbit and spina bifida. The spectrum of this syndrome is discussed, with possible relation to the degree of trisomy. The present case is the 6th to be reported with partial trisomy of the long arm of chromosome 3.

Child↗