A Cochrane review [Abstract] 1 included 3 studies with a total of 800 subjects. The participants in one trial did not have dementia, while the other two studies included participants with dementia of different severities. The dose of rivastigmine was different in each study. No pooling of study results was attempted because of these differences.
In a trial (n=40) with subcortical vascular dementia (VAD, age range 40 to 90 years) and with a mean mini-mental state examination (MMSE) score of 13.0 and 13.4 in the rivastigmine and placebo arms, respectively, the patients were treated over 26 weeks (3 mg rivastigmine twice daily). No significant difference was found on any outcome measure relevant to cognition, neuropsychiatric symptoms, function or global rating, or in the number of withdrawals before the end of treatment.
Another trial (n=710, age range 50 to 85 years) included subcortical and cortical forms of VAD patients for a treatment over 24 weeks (rivastigmine of 9.4 mg/day) Baseline MMSE was 19.1for both groups. Statistically significant advantage in cognitive response (but not with global impression of change or non-cognitive measures) was seen with rivastigmine (MMSE change from baseline MD 0.6, 95% CI 0.11 to 1.09; Vascular Dementia Assessment Scale (VaDAS) change from baseline MD -1.3, 95% CI-2.62 to 0.02). Significantly higher rates of vomiting, nausea, diarrhoea and anorexia and withdrawals from treatment were noted in the participants randomized to rivastigmine compared with placebo (withdrawals rivastigmine 90/365, placebo 48/345, OR 2.02, 95% CI 1.38 to 2.98) (withdrawals due to an adverse event rivastigmine 49/365, placebo 19/345, OR 2.66, 95% CI 1.53 to 4.62).
The third trial (n=50, age range 48 to 84 years) had mean MMSE scores of 23.7 and 23.9 in the rivastigmine and placebo arms, respectively. Participants with cognitive impairment but no dementia following ischaemic stroke were given up to 4.5 mg rivastigmine twice daily for 24 weeks. Primary and secondary outcome measures showed no statistically significant difference when considering neurocognitive abilities, function, neuropsychiatric symptoms and global performance.
Comment: The quality of the evidence is downgraded by imprecise results (few patients in two trials) and indirectness of evidence (short follow up time).
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