Results, rhetoric, and randomized trials: The case of donepezil

Whether donepezil provides meaningful benefit to patients with Alzheimer's disease (AD) is controversial, but drug sales annually total billions of dollars. A review of data from published randomized clinical trials (RCTs) found rhetorical patterns that may encourage use of this drug. To create a reproducible observation, the sentences occurring at five specific text sites in all 18 RCTs of donepezil for AD were tabulated, as were study design, sources of financial support, and outcomes that could be compared between trials. Rhetoric in the 13 vendor-supported trials (15 publications) was strongly positive. Three early trials used the motif "efficacious (or effective) ... treating ... symptoms" four times. "Well-tolerated and efficacious" or an equivalent motif appeared 11 times in five RCTs. Nine RCTs referred 15 times to previously proven effectiveness. Seven trials encourage off-label use, for "early" cognitive impairment, severe dementia in advance of the Food and Drug Administration labeling change, or behavioral symptoms. These rhetorical motifs and themes appeared only in the vendor-supported trials. Trials without vendor support described the drug's effects as "small" or absent; two emphasized the need for better treatments. RCT results were highly consistent in all trials; the small differences do not explain differences in rhetoric. At these text sites in the primary research literature on donepezil for AD, uniformly positive rhetoric is present in all vendor-supported RCTs. Reference to the limited benefit of donepezil is confined to RCTs without vendor support. Data in the trials are highly consistent. This observation generates the hypothesis that rhetoric in vendor-supported published RCTs may promote vendors' products.