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Editor's Correspondence
Octomber 12, 2009

Adverse Events in Patients Receiving Cholinesterase Inhibitors Due to Dissimilar Follow-up Periods—Reply

Arch Intern Med. 2009;169(18):1718-1725. doi:10.1001/archinternmed.2009.348

In reply

We thank Dr Chan for his interest in our study,1 and we agree that cholinesterase inhibitors may provide clinical benefits for some patients with Alzheimer disease. The goal of our study was to better characterize underrecognized adverse effects of these medications. Dr Chan highlights the shorter mean follow-up time among cholinesterase inhibitor users compared with nonusers in our study, which was detailed in Table 3 of our article.1 These findings are similar to those in randomized trials, in which it has been consistently demonstrated that there is a higher dropout rate for patients assigned to treatment with cholinesterase inhibitors than for patients assigned to placebo.2 Clinical experience supports this observation, which appears to be due primarily to adverse drug effects such as nausea and diarrhea. Thus, the patients who used cholinesterase inhibitors in our study had less opportunity to develop syncope-related outcomes compared with the control subjects. As a result, the number of events per 1000 person-years provides a more accurate reflection of harm than do crude event rates. Nonetheless, we presented both figures in Table 3.1

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