Pneumococcal vaccination for the elderly in The Netherlands? Assessment of the quality and content of available comparative studies.

BACKGROUND

A question that is currently topical in the Netherlands is whether it makes sense to introduce on a national scale vaccination against pneumococcal infections for elderly people who are at present receiving the influenza vaccination. We recently studied the scientific literature on the subject in an attempt to answer this question.

METHODS

We searched for systematic reviews (SRs), randomised clinical trials (RCTs) and cohort studies in MEDLINE, EMBASE, the Cochrane Library, Current Controlled Trials and via Google (period 1966 to June 2002). The SRs and RCTs were assessed with a methodological checklist.

RESULTS

We identified four SRs, two trials (of which one was pseudo-random) and one retrospective cohort study. The methodological quality of the SRs was reasonable and in this respect differed little among themselves. The SRs differed strongly with regard to subgroups, outcome measures, valency of vaccines, duration of follow-up and combination with influenza vaccination. The SRs showed that vaccination has more effect in low-risk groups, does not appear to be effective in high-risk patients and the elderly and is more effective in nonindustrialised countries. The outcomes based on the various outcome measures showed major differences. The three studies into the effectiveness of the pneumococcal vaccination in the elderly all showed major methodological shortcomings. For the majority of outcome measures the outcomes were negative.

CONCLUSION

There is insufficient convincing evidence in favour of the introduction of the pneumococcal vaccination as a supplement to influenza vaccination for the elderly. It seems as if (international) opinion had already been fully formed before published studies and systematic reviews become available in the last few years. It is perhaps worth considering setting up a prospective trial in the elderly Dutch population.