Evidence synthesis and decision modelling in public health

This thesis focuses on the challenges of evidence synthesis to inform healthcare decision making within public health. It encompasses both methodological advancement and practical application of existing synthesis methodology, using as an example - accidents prevention in children to illustrate application of the methods within a public health context. The thesis commences with a systematic review of NICE public health appraisals to identify the barriers to quantitative synthesis of evidence in public health. Then focusing on the prevention of unintentional poisonings in pre-school children, a series of network metaanalyses of the effectiveness evidence are conducted, demonstrating how complex synthesis methodology can be employed to help overcome some challenges of evidence synthesis in a identified in the review of the NICE public health appraisals. New synthesis methodology is then developed in which the standard network meta-analysis model is first extended to include a covariate for the baseline risk and then to a multiple outcome settings. Baseline risk is a proxy for unmeasured but important patient-level characteristics, which may be modifiers of the treatment effect in a meta-analysis. Thus adjusting for it can account for heterogeneity across different study populations and identify those more likely to benefit from the intervention. The multiple outcome models account for the dependency structure within the data which is important in a decision modelling context, as correlations between effect estimates on different outcomes may have implications for estimating the net benefit associated with treatment. Finally, a substantive decision analytic model is presented incorporating results from the network meta-analysis and application of the methodology developed to the poison prevention data. The analyses suggest that compared to usual care, more intensive home safety interventions are more effective in preventing medicinal poisonings in pre-school children but are unlikely to be cost-effective for the UK NHS unless policy makers are willing to pay upwards of £75,000 for every QALY gained.