Economic evaluations of implemented vaccination programmes: key methodological challenges in retrospective analyses

Post-implementation evaluation should play an important role in assessing the success of public health programmes; however, the value for money achieved by vaccine programmes after introduction has received relatively little attention to date. In this article we explore the methodological challenges in these analyses and offer direction for future evaluations in the area. We identify alternative approaches to addressing these challenges, which include the estimation of disease changes attributable to vaccination efforts, the hypothetical no vaccination comparator scenario and the full benefit achieved by implemented vaccination programmes. We also outline other important considerations such as the evolution of prices over time. Further work needs to be done to explore these issues and to determine how the application of different approaches may impact on the results of evaluations in various circumstances. As retrospective analyses are likely to become more frequent and influential, it is important that both the benefits and the limitations of post-implementation evaluations are recognised and understood. We argue that it would be useful to establish a methodological framework to provide standards and guidance on how to undertake such analyses in the future.

Evolutions in both co-payment and generic market share for common medication in the Belgian reference pricing system

BACKGROUND

In Belgium, a co-insurance system is applied in which patients pay a portion of the cost for medicines, called co-payment. Co-payment is intended to make pharmaceutical consumers more responsible, increase solidarity, and avoid or reduce moral hazards.

OBJECTIVE

Our objective was to study the possible influence of co-payment on sales volume and generic market share in two commonly used medicine groups: cholesterol-lowering medication [statins (HMG-CoA reductase inhibitors) and fibrates] and acid-blocking agents (proton pump inhibitors and histamine H2 receptor antagonists).

METHODS AND DATA

The data were extracted from the Pharmanet database, which covers pharmaceutical consumption in all Belgian ambulatory pharmacies. First, the proportion of sales volume and costs of generic products were modelled over time for the two medicine groups. Second, we investigated the relation between co-payment and contribution by the national insurance agency using change-point linear mixed models.

RESULTS

The change-point analysis suggested several influential events. First, the generic market share in total sales volume was negatively influenced by the abolishment of the distinction in the maximum co-payment level for name brands and generics in 2001. Second, relaxation of the reimbursement conditions for generic omeprazole stimulated generic sales volume in 2004. Finally, an increase in co-payment for generic omeprazole was associated with a significant decrease in omeprazole sales volume in 2005. The observational analysis demonstrated several changes over time. First, the co-payment amounts for name-brand and generic drugs converged in the observed time period for both medicine groups under study. Second, the proportion of co-payment for the total cost of simvastatin and omeprazole increased over time for small packages, and more so for generic than for name-brand products. For omeprazole, both the proportion and the amount of co-payment increased over time. Third, over time the prescription of small packages shifted to an emphasis on larger packages.

CONCLUSIONS

As maximum co-payment levels decreased over time, they overruled the reference pricing system in Belgium. The changes in co-payment share over time also significantly affected sales volume, but whether physicians or patients are the decisive actors on the demand side of pharmaceutical consumption remains unclear.

Adaptive change-point mixed models applied to data on outpatient tetracycline use in Europe

In this paper, we propose a change-point mixed model to assess the change in the trend of outpatient antibiotic use in a Bayesian framework, where the change-points are unknown parameters of the model. Model selection using DIC indicates that the data supports the model with a country-specific change-point. The location of the change-points may be related to points in time where public health strategies aiming at increasing the awareness of the public to a more rational use of antibiotics or targeting to reduce overconsumption of antibiotics were initiated.