Alastair Fischer

A conceptual framework for public health: NICE's emerging approach

This paper outlines the National Institute for Health and Clinical Excellences (NICE) emerging conceptual framework for public health. This is based on the experience of the first 3 years of producing public health guidance at NICE (2005-2008). The framework has been used to shape the revisions to NICEs public health process and methods manuals for use post 2009, and will inform the public health guidance which NICE will produce from April 2009. The framework is based on the precept that both individual and population patterns of disease have causal mechanisms. These are analytically separate. Explanations of individual diseases involve the interaction between biological, social and related phenomena. Explanations of population patterns involve the same interactions, but also additional interactions between a range of other phenomena working in tandem. These are described. The causal pathways therefore involve the social, economic and political determinants of health, as well as psychological and biological factors. Four vectors of causation are identified: population, environmental, organizational and social. The interaction between the vectors and human behaviour are outlined. The bridge between the wider determinants and individual health outcomes is integration of the life course and the lifeworld.

The cost-effectiveness of public health interventions

BACKGROUND The need to make best use of limited resources in the English National Health Service is now greater than ever. This paper contributes to this endeavour by synthesizing data from cost-effectiveness evidence produced to support the development of public health guidance at the National Institute of Health and Clinical Excellence (NICE). No comprehensive list of cost-effectiveness estimates for public health interventions has previously been published in England. METHODS Cost-effectiveness estimates using English cost data were collected and analysed from 21 (of 26) economic analyses underpinning public health guidance published by NICE between 2006 and 2010. RESULTS Two hundred base-case cost-effectiveness estimates were analysed, 15% were cost saving (i.e. the intervention was more effective and cheaper than comparator). Eighty-five per cent were cost-effective at a threshold of £20,000 per quality-adjusted life year and 89% at the higher threshold of £30,000. A further 5.5% were above £30,000 and 5.5% of the interventions were dominated (i.e. the intervention was more costly and less effective than comparator). CONCLUSIONS The majority of public health interventions assessed are highly cost-effective. The next challenge is to provide commissioners with a framework that allows information from economic analyses to be combined with other criteria that supports making better investment decisions at a local level.

The appraisal of public health interventions: the use of theory

BACKGROUND Public health decision-making is hampered by inappropriate adherence to underpowered randomized controlled trials (RCTs) which give inconclusive results and lead to decision-makers being loath to recommend interventions with strong theoretical and observational support. METHODS We outline situations in which robust decisions about health interventions can be made without trial evidence. We present a new approach in which theory, causal models and past observations are given proper regard in the decision-making process. RESULTS Using our approach, we provide examples where the use of causal theories and observations in areas, such as salt reduction, smoking cessation and gardening to improve mental health, is sufficient for deciding that such interventions are effective for improving health without needing the support of underpowered RCTs. Particularly where RCT evidence is inconclusive, our approach may provide similar aggregate health outcomes for society for vastly lower cost. CONCLUSIONS When knowledge and theoretical understanding are unable sufficiently to reduce doubt about the direction of effect from an intervention, decisions should be made using evidence-based medicine approaches. There are, however, many cases where the combination of robust theory, causal understanding and observation are able to provide sufficient evidence of the direction of effect from an intervention that current practice should be altered.

Designing and Undertaking a Health Economics Study of Digital Health Interventions

This paper introduces and discusses key issues in the economic evaluation of digital health interventions. The purpose is to stimulate debate so that existing economic techniques may be refined or new methods developed. The paper does not seek to provide definitive guidance on appropriate methods of economic analysis for digital health interventions. This paper describes existing guides and analytic frameworks that have been suggested for the economic evaluation of healthcare interventions. Using selected examples of digital health interventions, it assesses how well existing guides and frameworks align to digital health interventions. It shows that digital health interventions may be best characterized as complex interventions in complex systems. Key features of complexity relate to intervention complexity, outcome complexity, and causal pathway complexity, with much of this driven by iterative intervention development over time and uncertainty regarding likely reach of the interventions among the relevant population. These characteristics imply that more-complex methods of economic evaluation are likely to be better able to capture fully the impact of the intervention on costs and benefits over the appropriate time horizon. This complexity includes wider measurement of costs and benefits, and a modeling framework that is able to capture dynamic interactions among the intervention, the population of interest, and the environment. The authors recommend that future research should develop and apply more-flexible modeling techniques to allow better prediction of the interdependency between interventions and important environmental influences.

Health care resource allocation: is the threshold rule good enough?

We review the foundations of resource allocation rules based on cost-effectiveness information. Comprehensive approaches, where a total budget is allocated in one go, require estimation of the costs and effects of all available health care programmes, which is unlikely to be practical. A common alternative is to assess individual programmes against a cost-effectiveness threshold. This has been shown to be efficient if the threshold is well calibrated and all programmes can be wholly or partially implemented with constant returns to scale. We discuss the feasibility of these assumptions, and the effects of relaxing them, concluding that programme indivisibility is unlikely to be a serious problem at a national level, but that miscalibration of the threshold and non-constant returns to scale might be. A rule that avoids these difficulties has been proposed previously: a new programme should only be implemented if it can be funded by cancelling another less effective programme. This could never reduce efficiency, unlike the threshold rule, though we show that it might sometimes fail to recommend an efficiency-improving change. We suggest a refinement of this reallocation rule based on explicit estimation of the costs and effects of partial implementation of the programmes under review. Research is required to assess the practicality of this option.

Preventing dementia by promoting physical activity and the long-term impact on health and social care expenditures.

BACKGROUND Preventing dementia has been proposed to increase population health as well as reduce the demand for health and social care. Our aim was to evaluate whether preventing dementia by promoting physical activity (PA) a) improves population health or b) reduces expenditure for both health and social care if one takes into account the additional demand in health and social care caused by increased life expectancy. METHODS A simulation model was developed that models the relation between PA, dementia, mortality, and the use of health care and social care in England. With this model, scenarios were evaluated in which different assumptions were made about the increase in PA level in (part of) the population. RESULTS Lifetime spending on health and social care related to dementia was highest for the physically inactive (£28,100/£28,900 for 40-year-old males/females), but spending on other diseases was highest for those that meet PA recommendations (£55,200/£43,300 for 40-year-old males/females) due to their longer life expectancies. If the English population aged 40-65 were to increase their PA by one level, life expectancy would increase by 0.23years and health and social care expenditures would decrease by £400 per person. CONCLUSIONS Preventing dementia by increasing PA increases life expectancy and can result in decreased spending overall on health and social care, even after additional spending during life years gained has been taken into account. If prevention is targeted at the physically inactive, savings in dementia-related costs outweigh the additional spending in life years gained.

Measuring the contributions of prevention and treatment of illness to changing life expectancy with avoidable mortality as the outcome indicator: how to deal with new diseases

Abstract Background Avoidable mortality is an important outcome indicator of the effectiveness of health care. It is commonly used to quantify the contribution of health care to changes in life expectancy among people dying prematurely. This method assumes that the only determinants of avoidable mortality are those of health care, which can be separated into prevention and treatment contributions. However, there might be other determinants. If so, the apportionment into prevention or treatment gives an erroneous picture; this occurs when a new disease manifests itself, and mortality increases. We illustrate this by examining the history of HIV infection since its emergence as a new disease, and propose an alternative method for dealing with this anomaly. Methods We tried to examine what might have happened to premature mortality in England and Wales during 1980–2010 if there had been no means of preventing or treating HIV infection. We hoped to compare that scenario with what actually happened. The difference in mortality from HIV infection between the two scenarios would then have to be apportioned to prevention and treatment. However, because this scenario is unobservable, the case of South Africa, which allocated far fewer resources for prevention, was used as counterfactual. Findings With the existing methodology, prevention and treatment of HIV were estimated to have a negative contribution of 0·3% to the 2·02 years gained in life expectancy during 1980–94 and a positive contribution of 0·2% to the 1·62 years gained during 1994–2010. A negative contribution makes sense only when health care is failing. A comparison of what could have happened in life expectancy (a decline of 1·84 years) under lower levels of HIV prevention and what actually happened (the increase of 1·62 years) can be used to estimate the effect of the combination of prevention and treatment of HIV. This led to a positive and significantly larger estimate of a 73% contribution of HIV control to the decline in premature mortality. Interpretation Existing methodology of apportioning changes in life expectancy into prevention and treatment effects cannot deal with situations that result in increased mortality, particularly in the public health context where the effect can be large. Funding None.

The appraisal of public health interventions

Abstract Background Existing methods for the appraisal of public health interventions have been borrowed from those developed for the appraisal of health technology. They give precedence to randomised controlled trials (RCTs) and use a two-stage approach: a hypothesis-testing framework to establish an interventions effectiveness, followed by the use of decision theory to establish its cost effectiveness. This approach is not always appropriate for public health interventions, for which RCTs often do not exist, and those RCTs that do are often very underpowered. We propose instead the use of a (Bayesian) decision-theoretic approach for both effectiveness and cost effectiveness. Methods When evidence exists that includes RCTs that are sufficiently powered, our proposed approach will not change existing methods: the approach used in health technology appraisal would remain the same. However, in public health the role of theory in the formation of previous beliefs, as a means of establishing the direction of change of an outcome, becomes an important element in our proposed calculus. Another important element of our approach is that public heath decision makers should be risk-neutral. This aspect of decision theory, which has far-reaching consequences for appraisal, has not received the prominence it deserves, and does not appear to have been discussed previously. Findings Basing recommendations for public health on a restricted evidence base that requires the demonstration of a particular level of significance for its outcomes can lead to the rejection of interventions that would provide cost-effective improvements in population health. We will use case studies to show that interventions with small, non-significant effect size at the individual level, such as the imposition of 20 mph speed limits, can be cost effective at population level. Such interventions would, however, not be recommended with the standard approach of statistical significance from RCT evidence as the primary arbiter of effectiveness. Interpretation The changes we propose show that a decision-theoretic approach has great value for public health, just as it has in many other fields. Funding None.

Israel's ban on Ethiopians' blood

1 Connor EM, Sperling RS, Gelber R, et al. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine therapy. N Engl J Med 1994; 331: 1173–80. intubation, pelvic examination, and deliveries varied significantly between countries. For example, endotracheal intubation was done at least once by all but one US student, compared with only five of 18 German students, and eight of 29 English students. Most German students had no experience with pelvic examinations (never done by nine of 18), taking a cervical smear (12 of 18), or vaginal deliveries (13 of 18). By contrast, almost all the students in the US and England had experience with these basic obstetric and gynaecological skills. Although the number of students asked to take part in the survey is small, the data confirm our personal experience that the acquisition of clinical skills during medical school varies in different countries. We agree with McManus that the decline in clinical experience of UK medical students is of concern, but we like to stress that medical students in other countries, for example, Germany, will have even less opportunity to acquire essential and basic clinical skills before they qualify.

The cost-effectiveness of seven behavioural interventions to prevent drug misuse in vulnerable populations

BACKGROUND The National Institute for Health and Care Excellence (NICE) developed a guideline on drug misuse prevention in vulnerable populations. Part of the guideline development process involved evaluating cost-effectiveness and determining which interventions represented good value for money. METHODS Economic models were developed for seven interventions which aimed to prevent drug use in vulnerable populations. The models compared the costs (to the health and crime sectors) and health benefits (in quality-adjusted life years (QALYs)) of each intervention and its comparator. Sensitivity analysis explored the uncertainty associated with the cost of each intervention and duration of its effect. RESULTS The reduction in drug use for each intervention partly offset the costs of the intervention, and improved health outcomes (QALYs). However, with high intervention costs and low QALY gains, none of the interventions were estimated to be cost-effective in the base case. Sensitivity analysis found that some of the interventions could be cost-effective if they could be delivered at a lower cost, or if the effect could be sustained for more than two years. CONCLUSIONS For drug misuse prevention to be prioritised by funders, the consequences of drug misuse need to be understood, and interventions need to be shown to be effective and cost-effective. Quantifying the wider harms of drug misuse and wider benefits of prevention interventions poses challenges in evaluating the cost-effectiveness of drug misuse prevention interventions. A greater understanding of the consequences of drug misuse and causal factors could facilitate development of cost-effective interventions to prevent drug misuse.