From evidence-based to decision-analytic medicine: A mammography case study

The technology needed to implement mass screening by mammography existed well before the implementation of national screening programmes. This delay arose partly because of the complexities involved in conducting randomised controlled trials (RCTs) of screening programmes. These complexities not only extend the time needed to conduct trials of cancer screening, they reduce the external validity of the results. There is potential to improve the application of evidence-based medicine (EBM) to the evaluation of cancer screening programmes and other complex interventions through adding insights from Operational Research and Decision Theory. This would extend EBM to what might be called Decision-Analytic Medicine (DAM)

Aquaculture Productivity Convergence in India: A Spatial Econometric Perspective

This paper provides an illustration of evaluating productivity convergence using spatial econometric modelling framework for the aquaculture sector in India. Productivity has been measured using Total Factor Productivity (TFP). The b- and s-convergence concepts that are used to test the convergence hypothesis have been extended to examine the possible presence of spatial autocorrelation and spatial heterogeneity. The results have confirmed the productivity convergence hypothesis, the presence of spillover effects on TFP growth and the presence of spatial regimes in the TFP convergence process which have policy implications. The paper concludes by providing recommendations for further research.Agricultural and Food Policy,

Demand for Fish by Species in India: Three-stage Budgeting Framework

The demand studies for the fish sector are limited by their high degree of aggregation, and the lack of empirical basis for estimating the underlying elasticity of demand. In this study, the three-stage budgeting framework with quadratic almost ideal demand system (QAIDS) model has been used for fish demand analysis by species, using consumer expenditure survey data of India. Income and price elasticities of fish demand have been evaluated at mean level for different economic groups and have been used to project the demand for fish to a medium-term time horizon, by the year 2015. The domestic demand for fish by 2015 has been projected as 6.7-7.7 million tonnes. Aquaculture would hold the key to meet the challenges of future needs. Among species, Indian major carps (IMC) would play a dominating role in meeting the fish demand. Results have shown that the estimated price and income elasticities of demand vary across species and income classes. Fish species have not been found as homogenous commodities for consumers. All the eight fish types included in the study have been found to have positive income elasticity greater than one for all the income levels. Hence, with higher income, fish demand has been projected to increase substantially with change in the species mix. The own-price elasticities by species have been found negative and near to unitary.Agricultural and Food Policy,

Fish Supply Projections by Production Environments and Species Types in India

The supply studies on the fisheries sector in India have been addressed at the disaggregated level by production environment and by species groups. These would be more imperative and useful for assessing the fish supply at the national level. The fish supply projections by species groups under different production environments have been obtained to a medium-term horizon, by the year 2015 under various technological scenarios. The study has concluded that the supply response to fish price changes has been stronger under aquaculture than marine environment in India. Price and technology have been reported as the important instruments to induce higher supply. The change in the relative prices of fish species would change the species-mix in the total supply. The fish production has been projected as 4.6-5.5 million tonnes of inland fish and 3.2-3.6 million tonnes of marine fish by the year 2015. More than 60 per cent of the additional fish production will be contributed by aquaculture and mainly by the Indian major carps.Agricultural and Food Policy,

A Multistage Budgeting Approach to the Analysis of Demand for Fish: An Application to Inland Areas of Bangladesh

This study was conducted to estimate the elasticities of demand for eight different fish types and four income groups in Bangladesh using year-round data collected from inland areas of the country. It uses a three-stage budgeting framework that estimates a demand function for food in the first stage, a demand function for fish (as a group) in the second stage, and a set of demand functions for fish by type in the third stage using a quadratic extension of the Almost Ideal Demand System (QUAIDS) model. The Heckman procedure was used in stage three to remove the possible bias in the parameter estimates brought about by zero consumption. The magnitude of both price and income elasticities varies across different fish types and income quartile groups, indicating the relevance of estimation specific to fish types and quartiles. Except for assorted small fish, the other seven fish types included in the study were found to have positive income elasticity for all income levels. Assorted small fish is an inferior commodity for the richest quartile of the population.Bangladesh, fish demand elasticities, Inverse Mills Ratio, multi-stage budgeting, quadratic extension to Almost Ideal Demand System (QUAIDS), Demand and Price Analysis, International Development, Public Economics, Research Methods/ Statistical Methods, C3, Q21,

Granulocyte colony-stimulating factors for febrile neutropenia prophylaxis: systematic review and mixed method treatment comparison

Background This study assesses the efficacy of three granulocyte colony-stimulating factors (G-CSFs; pegfilgrastim, filgrastim and lenograstim) in preventing febrile neutropenia (FN). Methods A systematic review was undertaken. Head-to-head studies were combined using direct meta-analyses. In addition, an indirect Bayesian mixed treatment comparison (MTC) was undertaken to facilitate comparison between G-CSFs where there were no direct trials, and to allow data from all trials to be synthesised into a coherent set of results. Results The review identified the following studies comparing G-CSF prophylaxis to no primary G-CSF prophylaxis: 5 studies of pegfilgrastim, 9 studies of filgrastim and 5 studies of lenograstim. In addition, 5 studies were identified comparing pegfilgrastim to filgrastim. The two synthesis methods (meta-analysis and MTC) demonstrated that all three G-CSFs significantly reduced FN rate. Pegfilgrastim reduced FN rate to a greater extent than filgrastim (significantly in the head-to-head meta-analysis and in the MTC of all studies, and not quite significantly when the MTC was restricted to RCTs only). In the absence of direct trials, the MTC gave an 80-86% probability that pegfilgrastim is superior to lenograstim in preventing FN, and a 71-72% probability that lenograstim is superior to filgrastim. Conclusions Prophylaxis with G-CSFs significantly reduces FN rate. A head-to-head meta-analysis shows pegfilgrastim to be significantly superior to filgrastim in preventing FN events, while an MTC demonstrates that pegfilgrastim is likely to be superior to lenograstim

Consistency between direct trial evidence and Bayesian Mixed Treatment Comparison: Is head-to-head evidence always more reliable?

Objectives: This study aims to highlight the benefits of Bayesian mixed treatment comparison (MTC), within a case study of the efficacy of three treatments (pegfilgrastim, filgrastim and lenograstim) for the prevention of febrile neutropenia (FN) following chemotherapy. Methods: Two published meta-analyses have assessed the relative efficacy of the three treatments based on head-to-head trials. In the present study, all the trials from these meta-analyses were synthesised within a single network in a Bayesian MTC. Following a systematic review, the evidence base was then updated to include further recently-published trials. The metaanalyses and MTC were re-analysed using the updated evidence base. Results: Using data from the previously-published meta-analyses only, the relative risk of FN for pegfilgrastim vs. no treatment was estimated at 0.08 (95% confidence interval: 0.03, 0.18) from the head-to-head trial and 0.27 (95% credible interval: 0.12, 0.60) from the MTC, reflecting strong inconsistency between the results of the direct and indirect methodologies. When subsequently-published head-to-head trials were included, the meta-analysis estimate increased to 0.29 (95% confidence interval: 0.15, 0.55), while the MTC gave a relative risk of 0.34 (95% credible interval: 0.23, 0.54). The initial MTC results were therefore a better predictor of subsequent study results than was the direct trial. The MTC was also able to estimate the probability that there were clinically significant difference in efficacy between the treatments. Conclusions: Bayesian MTC provides clinically relevant information, including a measure of the consistency of direct and indirect evidence. Where inconsistency exists, it should not always be assumed that the direct evidence is more appropriate

Consistency between direct trial evidence and Bayesian Mixed Treatment Comparison: Is head-to-head evidence always more reliable?

Objectives This study aims to highlight the benefits of Bayesian mixed treatment comparison (MTC), within a case study of the efficacy of three treatments (pegfilgrastim, filgrastim and lenograstim) for the prevention of febrile neutropenia (FN) following chemotherapy. Methods Two published meta-analyses have assessed the relative efficacy of the three treatments based on head-to-head trials. In the present study, all the trials from these meta-analyses were synthesised within a single network in a Bayesian MTC. Following a systematic review, the evidence base was then updated to include further recently-published trials. The metaanalyses and MTC were re-analysed using the updated evidence base. Results Using data from the previously-published meta-analyses only, the relative risk of FN for pegfilgrastim vs. no treatment was estimated at 0.08 (95% confidence interval: 0.03, 0.18) from the head-to-head trial and 0.27 (95% credible interval: 0.12, 0.60) from the MTC, reflecting strong inconsistency between the results of the direct and indirect methodologies. When subsequently-published head-to-head trials were included, the meta-analysis estimate increased to 0.29 (95% confidence interval: 0.15, 0.55), while the MTC gave a relative risk of 0.34 (95% credible interval: 0.23, 0.54). The initial MTC results were therefore a better predictor of subsequent study results than was the direct trial. The MTC was also able to estimate the probability that there were clinically significant difference in efficacy between the treatments. Conclusions Bayesian MTC provides clinically relevant information, including a measure of the consistency of direct and indirect evidence. Where inconsistency exists, it should not always be assumed that the direct evidence is more appropriate