The purpose of this paper is to highlight a fundamental gap in the economic research on obesity -- the demand for unnecessary weight gain preventive goods. Such research is important as it will provide understanding of people's preventive behaviours and for that matter inform policies and practices with regards to influencing people's uptake of obesity preventive goods. Using MeSH and PICO approaches, a search strategy was developed to search for relevant articles in a number of academic and scientific journal repositories including PubMed Central, EconLit, Medline, Medscape and relevant (economic) journals' archives. A total of 1351 potentially relevant articles (titles and abstracts) were reviewed. No publications could be found that concerned people's preventive behaviours in terms of demand with respect to obesity preventive goods. Only one article which was not specific to obesity looked into people's preventive behaviours using an economic model. Despite the huge economic and health burden of obesity, participations in activities deemed supportive to weight gain prevention are dismal.

Abstract
Objectives? To evaluate the cost effectiveness of the use of nine-valent pneumococcal polysaccharide conjugate vaccine in a routine infant immunisation programme based on the Pneumococcal Vaccine Trial (PVT) study in The Gambia.
Methods? This was a clinical trial-based cost-effectiveness study conducted as part of the PVT study. The PVT was an intention-to-treat double-blind placebo-controlled trial of a nine-valent pneumococcal polysaccharide conjugate vaccine. The trial was conducted in the eastern parts of The Gambia, West Africa and recruited 17 437 children aged 40?364 days. A deterministic static cohort model was developed to evaluate direct benefits and costs of pneumococcal conjugate vaccine in The Gambia's routine immunisation programme. The incremental cost-effectiveness ratio (iCER) is defined as vaccinating infants against pneumococcal disease compared with no vaccination from a public provider's perspective using The Gambia's 2005 projected under-one-year population.
Key findings? The results show the use of the vaccine in The Gambia's routine infant vaccination programme to be cost effective using an assumed price of US$5.00 per vial in single-dose vials. Compared with offering no vaccination, the incremental cost per DALYs averted would be 30 DALYs from the public provider perspective. At least 1569 and 340 invasive childhood pneumococcal illnesses and deaths respectively among the cohort would be prevented. In the absence of the vaccine 16 871 DALYs would be lost while with the use of the vaccine 7804 DALYs would be lost. Given the average treatment cost of pneumococcal illnesses to be US$191 (95% confidence interval 180 to 203) the introduction of the vaccine programme would lead to an additional cost of US$274 279 (about US$8.43/child).
Conclusions? The availability of a cost-effective vaccine that can prevent thousands of pneumococcal illnesses and related deaths is a major development towards improving the disease burden in sub-Saharan African countries. This study supports the introduction of nine-valent pneumococcal vaccine into the infant immunisation programme of The Gambia as it is cost effective and will avert many preventable deaths and illnesses. Despite differences in distribution of serotypes between countries, the static model used in the analysis makes the results applicable to other developing countries, particularly those in sub-Saharan Africa.

Introduction: Obesity is one of the leading causes of preventable morbidity and mortality world-wide. The behavioural nature of the condition has been highlighted by the fact that it is largely the result of an energy imbalance between calories consumed and calories expended. In that respect, obesity related morbidity and mortality can be reduced through preventive behaviours. As behavioural scientists, economists have done little to date to explain and understand why the demand for obesity preventing activities is low. The aim of this paper is to develop an economic theory-based dynamic model to gain better understanding of people?s obesity preventive behaviours. Methods: A literature search using a PICO approach was developed to identify the relevant variables considered to influence the demand for obesity preventive goods. To inform the model, a framework was developed to group variables and help determine appropriate linkages between them. Results: Anchors, anxiety and anxiety driven variables are fundamental influences of people?s risk reduction actions. The anchors, which are environmental as well as personal in character, serve as references and stimulate anxieties. However, anxiety levels are driven by many other variables including stigma and perceived health outcomes. In response to one?s anxiety an individual will take actions which can be explained, at least in part, by conventional economic theories particularly in terms of costs and utilities. Conclusions: Conventional economic theories of consumer behaviour cannot fully explain the demand for obesity preventive goods. The model demonstrates that many factors have to be considered including health economic, psychological and behavioural economic theories. The model should be tested through a well designed questionnaire before using it in a general adult population.

Objectives

The objectives were to investigate the impact of ?time-effect? on the estimation of quality-adjusted life years (QALYs) along prospective clinical trials? outcomes using an assumed fixed time duration versus the actual time durations for each case. The ?time? duration is the length of time in a health state.

Methods

Two methods were used in the estimation of QALYs based using EQ-5D 3L scores collected at specific time-point intervals. One method used the actual time durations for each case based on CRF records, and the other used an assumed time duration and globally applied it to all the cases. Using SPSS® software program, we used paired-sample t-tests to assess whether the ?time-effect? can potentially affect trial results using CONSTRUCT trial data as reported in the trial results publications. The trial compared use of Infliximab with Cyclosporine for patients with Ulcerative Colitis and it involved some 270 participants.

Key findings

The results largely indicate statistically significant differences between the two methods of QALY estimations. QALYs at the respective time-points indicate no statistical difference between the two approaches. However, the difference in terms of total QALYs between the two QALY estimation approaches is statistically significant with considerable impact on costs/QALY.

Conclusions

Considering the possible impact of the time-effect on QALY estimations, the result implies that it can have significant implications for resources allocations decisions. In this respect, researchers have to pay due considerations to the approach they use and where possible, actual time durations must be used in QALY estimations along prospective clinical trials.