The cost-effectiveness of weight management programmes in a postnatal population.

OBJECTIVES: The aim of the study was to estimate the cost-effectiveness of a weight management programme including elements of physical exercise and dietary restriction which are designed to help women lose excess weight gained during pregnancy in the vulnerable postnatal period and inhibit the development of behaviours which could lead to future excess weight gain and obesity. STUDY DESIGN: A mathematical model based on a regression equation predicting change in weight over a fifteen year postnatal period was developed. METHODS: The model included programme effectiveness and resource data based on a randomized controlled trial of a weight management programme implemented in a postnatal population in the United States. Utility and mortality data based on body mass index categories were also included. The model adopted a National Health Service (NHS) and personal social services (PSS) perspective, a lifetime time horizon and estimated the cost effectiveness of a weight management programme against a no change comparator in terms of an incremental cost-effectiveness ratio (ICER). RESULTS: The baseline results show that the difference in weight between women who received the weight management programme and women who received the control intervention was 3.02 kg at six months and 3.53 kg at fifteen years following childbirth. This results in an ICER of £7355 per quality adjusted life year (QALY) for women who were married at childbirth. CONCLUSION: The estimated ICER would suggest that such a weight management programme is cost-effective at a NICE threshold of £20,000 per QALY. However significant structural and evidence based uncertainty is present in the analysis.

The clinical effectiveness and cost-effectiveness of home-based, nurse-led health promotion for older people: a systematic review.

BACKGROUND: In older age, reduction in physical function can lead to loss of independence, the need for hospital and long-term nursing or residential home care, and premature death. Home-visiting programmes for older people, carried out by nurses and other health-care professionals (e.g. occupational therapists and physiotherapists), aim to positively affect health and functional status, and may promote independent functioning of older people. OBJECTIVE: The main research question addressed by this assessment is 'What is the clinical effectiveness and cost-effectiveness of home-based, nurse-led health promotion intervention for older people in the UK?' DATA SOURCES: A comprehensive literature search was undertaken across 12 different databases and research registries from the year 2001 onwards (including MEDLINE, MEDLINE in Process & Other Non-Indexed Citations, EMBASE, Science Citation Index Expanded, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, NHS Health Economic Evaluation Database, Health Technology Assessment Database, Database of Abstracts of Reviews of Effects, Cumulative Index to Nursing and Allied Health Literature). Published systematic reviews were also hand searched to identify other trials previously published. REVIEW METHODS: Potentially relevant studies were sifted by one reviewer, and inclusion decisions were agreed among the broader research team. The methodological quality of included studies was assessed using the Cochrane Risk of Bias tool. The results of included studies were synthesised using narrative and statistical methods. A separate systematic search was undertaken to identify existing health economic analyses of home-based, nurse-led health promotion programmes. Included studies were critically appraised using a published checklist. Owing to resource constraints, a de novo health economic model was not developed. RESULTS: Eleven studies were included in the systematic review of clinical effectiveness. There was considerable heterogeneity among the studies with respect to the nature of the intervention, the nurses delivering the programmes and the populations in which the interventions were assessed. Overall, the quality of the included studies was good: all but one of the included studies were judged to be at medium or low risk of bias. Meta-analysis of eight studies suggested a statistically significant mortality benefit for the home-based health promotion groups, whereas a meta-analysis of four studies suggested non-significant benefits in terms of fewer falls in the intervention groups than in the control groups. Positive outcomes for home-based, nurse-led health promotion interventions were also reported within individual studies across several other outcomes. Only three economic studies met the criteria for inclusion in the review of cost-effectiveness. This evidence base consists of one non-randomised cost minimisation analysis and two economic evaluations undertaken alongside randomised controlled trials. Two of these studies involved an intervention targeted specifically at patients with a known underlying incurable disease, whereas the third study examined the clinical effectiveness and cost-effectiveness of early discharge in patients with a range of conditions, including fractures, neurological conditions and cardiorespiratory conditions. Each study indicated some likelihood that home-based, nurse-led health promotion may offer cost savings to the NHS and associated sectors, such as social services. However, one study did not report any comparison of health outcomes and instead simply assumed equivalence between the intervention and comparator groups, whereas the other two studies suggested at best a negligible incremental benefit in terms of preference-based health-related quality-of-life measures. LIMITATIONS: The evidence base for clinical effectiveness is subject to considerable heterogeneity. The UK economic evidence base is limited to three studies. CONCLUSIONS: On the basis of the evidence included in this systematic review, home-based, nurse-led health promotion may offer clinical benefits across a number of important health dimensions. However, it is generally unclear from the available studies which components of this type of complex intervention contribute towards individual aspects of benefit for older people. Given the limitations of the current evidence base, it remains unclear whether or not home-based health promotion interventions offer good value for money for the NHS and associated sectors. Given the considerable uncertainties in the available evidence base, it is difficult to isolate the key areas in which future research would be valuable or the exact study design required. Although this report does not identify specific studies that should be undertaken, it does set out a number of key considerations for the design of future research in this area. STUDY REGISTRATION: PROSPERO number: CRD42012002133.

Avoiding and identifying errors in health technology assessment models: qualitative study and methodological review.

BACKGROUND: Health policy decisions must be relevant, evidence-based and transparent. Decision-analytic modelling supports this process but its role is reliant on its credibility. Errors in mathematical decision models or simulation exercises are unavoidable but little attention has been paid to processes in model development. Numerous error avoidance/identification strategies could be adopted but it is difficult to evaluate the merits of strategies for improving the credibility of models without first developing an understanding of error types and causes. OBJECTIVES: The study aims to describe the current comprehension of errors in the HTA modelling community and generate a taxonomy of model errors. Four primary objectives are to: (1) describe the current understanding of errors in HTA modelling; (2) understand current processes applied by the technology assessment community for avoiding errors in development, debugging and critically appraising models for errors; (3) use HTA modellers' perceptions of model errors with the wider non-HTA literature to develop a taxonomy of model errors; and (4) explore potential methods and procedures to reduce the occurrence of errors in models. It also describes the model development process as perceived by practitioners working within the HTA community. DATA SOURCES: A methodological review was undertaken using an iterative search methodology. Exploratory searches informed the scope of interviews; later searches focused on issues arising from the interviews. Searches were undertaken in February 2008 and January 2009. In-depth qualitative interviews were performed with 12 HTA modellers from academic and commercial modelling sectors. REVIEW METHODS: All qualitative data were analysed using the Framework approach. Descriptive and explanatory accounts were used to interrogate the data within and across themes and subthemes: organisation, roles and communication; the model development process; definition of error; types of model error; strategies for avoiding errors; strategies for identifying errors; and barriers and facilitators. RESULTS: There was no common language in the discussion of modelling errors and there was inconsistency in the perceived boundaries of what constitutes an error. Asked about the definition of model error, there was a tendency for interviewees to exclude matters of judgement from being errors and focus on 'slips' and 'lapses', but discussion of slips and lapses comprised less than 20% of the discussion on types of errors. Interviewees devoted 70% of the discussion to softer elements of the process of defining the decision question and conceptual modelling, mostly the realms of judgement, skills, experience and training. The original focus concerned model errors, but it may be more useful to refer to modelling risks. Several interviewees discussed concepts of validation and verification, with notable consistency in interpretation: verification meaning the process of ensuring that the computer model correctly implemented the intended model, whereas validation means the process of ensuring that a model is fit for purpose. Methodological literature on verification and validation of models makes reference to the Hermeneutic philosophical position, highlighting that the concept of model validation should not be externalized from the decision-makers and the decision-making process. Interviewees demonstrated examples of all major error types identified in the literature: errors in the description of the decision problem, in model structure, in use of evidence, in implementation of the model, in operation of the model, and in presentation and understanding of results. The HTA error classifications were compared against existing classifications of model errors in the literature. A range of techniques and processes are currently used to avoid errors in HTA models: engaging with clinical experts, clients and decision-makers to ensure mutual understanding, producing written documentation of the proposed model, explicit conceptual modelling, stepping through skeleton models with experts, ensuring transparency in reporting, adopting standard housekeeping techniques, and ensuring that those parties involved in the model development process have sufficient and relevant training. Clarity and mutual understanding were identified as key issues. However, their current implementation is not framed within an overall strategy for structuring complex problems. LIMITATIONS: Some of the questioning may have biased interviewees responses but as all interviewees were represented in the analysis no rebalancing of the report was deemed necessary. A potential weakness of the literature review was its focus on spreadsheet and program development rather than specifically on model development. It should also be noted that the identified literature concerning programming errors was very narrow despite broad searches being undertaken. CONCLUSIONS: Published definitions of overall model validity comprising conceptual model validation, verification of the computer model, and operational validity of the use of the model in addressing the real-world problem are consistent with the views expressed by the HTA community and are therefore recommended as the basis for further discussions of model credibility. Such discussions should focus on risks, including errors of implementation, errors in matters of judgement and violations. Discussions of modelling risks should reflect the potentially complex network of cognitive breakdowns that lead to errors in models and existing research on the cognitive basis of human error should be included in an examination of modelling errors. There is a need to develop a better understanding of the skills requirements for the development, operation and use of HTA models. Interaction between modeller and client in developing mutual understanding of a model establishes that model's significance and its warranty. This highlights that model credibility is the central concern of decision-makers using models so it is crucial that the concept of model validation should not be externalized from the decision-makers and the decision-making process. Recommendations for future research would be studies of verification and validation; the model development process; and identification of modifications to the modelling process with the aim of preventing the occurrence of errors and improving the identification of errors in models.

Thrombophilia testing in people with venous thromboembolism: systematic review and cost-effectiveness analysis.

OBJECTIVES: To assess whether thrombophilia testing following a venous thrombotic event is clinically effective and cost-effective in the management of thrombosis compared with no testing for thrombophilia. DATA SOURCES: Major electronic databases were searched from September to November 2006. REVIEW METHODS: A systematic review of the clinical effectiveness and cost-effectiveness literature was undertaken according to standard methods. A discrete event simulation model was constructed to assess the cost-effectiveness of changing the standard 3-month duration of warfarin treatment to 10 years, 20 years or lifelong. RESULTS: No clinical studies were identified that met the inclusion criteria for the systematic review. Further literature searches and clinical opinion were therefore used to inform the cost-effectiveness analysis. Thrombophilia testing in patients with pulmonary embolism (PE) had an estimated mean cost per quality-adjusted life-year (QALY) of below 20,000 pounds regardless of sex or age. In patients with a previous deep vein thrombosis (DVT), thrombophilia testing had an estimated mean cost per QALY of below 20,000 pounds in men aged 69 years or less and in women aged 49 years or less. The estimated duration of warfarin treatment (lifelong, 20 years, 10 years or no extended treatment) that was most cost-effective is presented for each age, sex, initial venous thromboembolism (VTE) event and type of thrombophilia. CONCLUSIONS: In terms of determining the duration of anticoagulation management, scenarios were found in which the cost per QALY of thrombophilia testing was below 20,000 pounds. However, these results are subject to great uncertainty, largely because of lack of knowledge about the increased risk of recurrence with each type of thrombophilia. Results are influenced by the fact that men have a greater risk of recurrence than women and by the fact that the frequency of adverse events associated with warfarin treatment increases with age. Further research, for example on the likely sensitivity and specificity of the tests for specific types of thrombophilia, is needed to reduce the uncertainty associated with these results. Studies comparing patients with VTE tested for thrombophilia with those whose risk assessment was based on personal and family history of thrombosis would also be beneficial.