Although generally interesting, the meta-analysis by Krista Lanctôt and associates1 of the efficacy and safety of cholinesterase inhibitors in the treatment of Alzheimer's disease simply demonstrates what is observed in day-to-day clinical practice: a slight improvement or stabilization of the disease (as indicated by neuropsychological evaluation) and various gastrointestinal side effects. The meta-analysis showed a slightly greater benefit with donepezil than with the other drugs — again, just what is observed in daily clinical practice.
Unfortunately, the extensive support that some of the authors received from the pharmaceutical industry, as outlined in the competing interests statement,1 might taint readers' perception of the authors' autonomy and independent interpretation of their findings. It is of course important to disclose potential competing interests, yet it is very difficult for readers to evaluate their influence on a study's conclusions. Furthermore, it might be useful if meta-analyses were to also include the competing interests of the authors of the papers included in the analysis. For example, the Japanese study2 that showed a substantial treatment effect with donepezil — ascribed in the meta-analysis1 to specific gene frequencies in the Japanese population — might have been influenced by the competing interests of its authors. As more and more clinical research is funded by companies with a financial interest in the outcomes, there may be greater pressure on researchers to assess and report their financial interests.
Celio Levyman Neurologist Saó Paulo, Brazil
Footnotes
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Competing interests: None declared.