Comprehensive decision analytical modelling in economic evaluation: a Bayesian approach

Decision analytical models are widely used in economic evaluation of health care interventions with the objective of generating valuable information to assist health policy decision-makers to allocate scarce health care resources efficiently. The whole decision modelling process can be summarised in four stages: (i) a systematic review of the relevant data (including meta-analyses), (ii) estimation of all inputs into the model (including effectiveness, transition probabilities and costs), (iii) sensitivity analysis for data and model specifications, and (iv) evaluation of the model. The aim of this paper is to demonstrate how the individual components of decision modelling, outlined above, may be addressed simultaneously in one coherent Bayesian model (sometimes known as a comprehensive decision analytical model) and evaluated using Markov Chain Monte Carlo simulation implemented in the specialist software WinBUGS. To illustrate the method described, it is applied to two illustrative examples: (1) The prophylactic use of neurominidase inhibitors for the prevention of influenza. (2) The use of taxanes for the second-line treatment of advanced breast cancer.The advantages of integrating the four stages outlined into one comprehensive decision analytical model, compared to the conventional 'two-stage' approach, are discussed.     

Responses to standard gambles: are preferences ‘well constructed’?

Standard gamble (SG) is commonly used to elicit preferences in order to assess health related quality of life. There has been little qualitative research exploring how respondents answer such questions. An SG study was designed to elicit values for the health states associated with anti-hypertensive medication, stroke and cardiovascular disease. This paper describes a qualitative study that was carried out alongside the SG exercise in order to document the thought processes respondents bring to bear in formulating their responses. Data were generated using 'think aloud' techniques and semi-structured interviews. Values were generally well-constructed: responses were thoroughly considered, and respondents made complex trade-offs and arrived at a point of indifference. However, some respondents incorporated inappropriate information into their choices, redefining the hypothetical 'Option B' resulting in problems interpreting the probabilistic information. Consideration of non-health factors was commonplace, in particular the impact of choices on others. We discuss these findings in terms of the use of qualitative methods in health economics and the wider discourse surrounding the theoretical underpinnings of health state valuation.     

Simulation of a Hirschman-Herfindahl index without complete market share information

This paper utilizes maximum likelihood methods to simulate a Hirschman-Herfindahl index (HHI) for markets in which complete market share information is unavailable or delayed. Many jurisdictions either may be unable to administratively collect data or experience delays in collection that make data regarding turbulent markets of limited use. With the development of this method, regulatory authorities monitoring health-care competition or health-care firms can now use market surveys--in which reliable recall is often limited to the largest three or four firms--to produce an on-the-spot measure of market concentration.     

Framing the doctor-patient relationship in chronic illness: a comparative study of general practitioners' accounts

How family doctors conceptualise chronic illness in the consultation has important implications for both the delivery of medical care, and its experience by patients. In this paper, we present the results of a re-analysis of qualitative data collected in a series of studies of British family doctors between 1995 and 2001, to explore the ways in which the legitimacy and authority of medical knowledge and practice are organised and worked out in relation to three kinds of chronic illness (menorrhagia; depression; and chronic low back pain/medically unexplained symptoms). We present a comparative analysis of (a). the moral evaluation of the patient (and judgements about the legitimacy of symptom presentation); (b). the possibilities of disposal; and (c). doctors' empathic responses to the patient, in each of these clinical cases. Our analysis defines some of the fundamental conditions through which general practitioners frame their relationships with patients presenting complex but sometimes diffuse combinations of 'social', 'psychological' and 'medical' symptoms. These are fundamental to, yet barely touched by, the increasingly voluminous literature on how doctors should interact with patients. Moving beyond the individual studies from which our data are drawn, we have outlined some of the highly complex and demanding features of what is often seen as routine and unrewarding medical work, and some of the key requirements for the local negotiation of patients' problems and their meanings (for both patients and doctors) in everyday general practice.     

Maternal Dietary Risk Factors in Childhood Acute Lymphoblastic Leukemia (United States)

OBJECTIVE: Acute lymphoblastic leukemia (ALL) is the most common childhood cancer, and the second most common cause of mortality in children aged 1-14 years. Recent research has established that the disease can originate in utero, and thus maternal diet may be an important risk factor for ALL. METHODS: The Northern California Childhood Leukemia Study is a population-based case-control study of risk factors for childhood leukemia, including maternal diet. Cases (n = 138) and controls (n = 138) were matched on sex, date of birth, mother's race, Hispanicity, and county of residence at birth. Maternal dietary intake in the 12 months prior to pregnancy was obtained by a 76-item food frequency questionnaire. RESULTS: Consumption of the vegetables (OR = 0.53; 95% CI, 0.33-0.85; p = 0.008), protein sources (OR = 0.40; 95% CI, 0.18-0.90, p = 0.03), and fruits (OR = 0.71; 95% CI, 0.49-1.04; p = 0.08) food groups were inversely associated with ALL. Among nutrients, consumption of provitamin A carotenoids (OR = 0.65, 95% CI, 0.42-1.01; p = 0.05), and the antioxidant glutathione (OR = 0.42; 95% CI, 0.16-1.10; p = 0.08) were inversely associated with ALL. CONCLUSION: Maternal dietary factors, specifically the consumption of vegetables, fruits, protein sources and related nutrients, may play a role in the etiology of ALL. Dietary carotenoids and glutathione appear to be important contributors to this effect.     

Dementia Care Mapping reconsidered: exploring the reliability and validity of the observational tool

BACKGROUND: Dementia Care Mapping (DCM) is a widely used observational method for evaluating the service quality provided to people with dementia. However, there is little evidence concerning its reliability and validity when used by routine care staff for whom it was designed. METHOD: The study evaluated levels of inter-observer agreement; The ability of the five-minute time frame to reflect the 'actual passing of time'; And the nature of the relationship between individual Well/Ill-Being values (WIB) and dependency levels.Data collected using DCM and continuous time sampling (CTS) were compared. The methods were used in parallel where the CTS coder and the DCM mapper(s) observed the same participants.Observations were carried out with 64 people with dementia within a day hospital and a continuing care ward. Inter-observer agreement was calculated across 20 participants.Dependency levels were measured using the Clifton Assessment Procedure for the Elderly (CAPE) (Pattie and Gilleard, 1979). RESULTS: Low levels of inter-observer agreement were found where 11 of the 25 Behaviour Category codes and all six Well/Ill-being Codes produced unacceptable kappas (<0.6).The Behaviour coding frame provided a meaningful picture of activities participants engaged in, but significantly underestimated participant levels of inactivity.A strong relationship was demonstrated between participants' WIB score and levels of dependency, thus DCM was unable to measure well-/ill-being as a separate construct from participants' levels of dependency. CONCLUSIONS: Questions were raised regarding the reliability and validity of DCM as used by routine care staff. Possible reasons for this, and suggestions for amendments are made.     

Statistical methods for single-case studies in neuropsychology: comparing the slope of a patient's regression line with those of a control sample

Performance on some neuropsychological tests is best expressed as the slope of a regression line. Examples include the quantification of performance on tests designed to assess the accuracy of time estimation or distance estimation. The present paper presents methods for comparing a patient's performance with a control or normative sample when performance is expressed as slope. The methods test if there is a significant difference between a patient's slope and those obtained from controls, yield an estimate of the abnormality of the patient's slope, and provide confidence limits on the level of abnormality. The methods can be used with control samples of any size and will therefore be of particular relevance to single-case researchers. A method for comparing the difference between a patient's scores on two measures with the differences observed in controls is also described (one or both measures can be slopes). The methods require only summary statistics (rather than the raw data from the normative or control sample); it is hoped that this feature will encourage the development of norms for tasks that use slopes to quantify performance. Worked examples of the statistical methods are provided using neuropsychological data and a computer program (for PCs) that implements the methods is described and made available.     

用中和剂清除消毒剂残效的方法学探讨

目的：比较根据产品说明书中的有效成分配制(常规法)的中和剂和某院根据相关资料配制(试验法)的中和剂清除消毒剂残余杀菌能力的效果。方法：按常规法和试验法分别配制检测消毒剂戊二醛和碘伏的中和剂,并分别按《消毒技术规范》中的“中和剂鉴定试验”操作,进行中和残余杀菌的效果观察。结果：按试验法配制的中和剂可中和消毒剂残余的杀菌能力,且对细菌无抑制作用,按常规法配制的中和剂反之。结论：市售消毒剂多为复合型即含相关活性物,对其残余杀菌力进行清除时应同时中和其有效成分和活性物质,这样才能保证检测结果的准确性。     

Assessment of occupational safety and health programs in small businesses

BACKGROUND: Occupational safety and health (OSH) programs are a strategy for protecting workers' health, yet there are few peer-reviewed reports on methods for assessing them, or on the prevalent characteristics of OSH programs, especially in small businesses. METHODS: We adapted an occupational safety and health administration (OSHA) survey instrument to assess: management commitment and employee participation, workplace analysis, hazard prevention and control, and education and training. This was supplemented by a series of open-ended questions. We administered the survey in 25 small worksites. RESULTS: Scores for each element ranged widely, with distribution of most scores being positively skewed. Barriers to addressing OSH included lack of time and in-house expertise, and production pressures. External agents, including corporate parents, liability insurers, and OSHA, played an important role in motivating OSH programs. CONCLUSIONS: Small businesses were able to mount comprehensive programs, however, they may rely on outside resources for this task. Being small may not be a barrier to meeting the requirements of an OSHA program management rule.