Assessing the potential cost effectiveness of pneumococcal vaccines in the US. Methodological issues and current evidence

Pneumococcal disease imposes a notable burden on society, particularly in the elderly and those at high risk of complications. Preventive strategies, especially vaccines, are possibly the best way to minimise such a burden. We report on the conduct and results of a preliminary exploratory review of the economics of pneumococcal vaccines in the elderly population in the US. After extensive electronic and manual searches, we identified 5 economic evaluations that fulfilled our study criteria. From these we extracted key economic variables and assessed the quality of the studies against the criteria in the checklist for authors and peer reviewers of economic submissions to the British Medical Journal. We found variation of quality of study design such as a lack of clarity in the treatment of indirect costs and a failure to present the data on resource use and costs separately. We carried out supplementary searches to assess the quality of the epidemiological and efficacy evidence upon which the economic models were based and found contradictory evidence of effects of the vaccines, which included the results of 2 meta-analyses. One of these meta-analyses reported that retrospective studies, especially case-control studies, tended to underestimate the protective efficacy of the vaccine by as much as 20. We believe that a well resourced Cochrane review of the clinical evidence of the effects of the vaccines should be carried out before any further economic studies. No more economic modelling should take place before such a review is undertaken.