Rivastigmine for Alzheimer's disease: Canadian interpretation of intermediate outcome measures and cost implications

Background: Clinical studies have shown that patients with Alzheimer's dise ase (AD) who are treated with rivastigmine have statistically significantly better scores on 5 scales used to assess AD than control patients receivin g placebo. However, the clinical meaning and cost implications of these dif ferences are not clear. Objective: The purpose of this study was to assess the clinical meaning and cost implications of statistically significant results obtained in clinica l trials of rivastigmine for the treatment of AD. Potential cost implicatio ns for the health care system, caregivers, and society are considered. Methods: Data on clinical effects of rivastigmine were obtained from publis hed North American and European clinical studies of patients with mild to m oderately severe AD receiving rivastigmine 6 to 12 mg/d (n = 828) or placeb o (n = 647). Differences in scores on the Alzheimer's Disease Assessment Sc ale-Cognitive Function, Clinician's Interview-Based Impression of Change wi th both clinical and caregiver information considered, Progressive Deterior ation Scale, Mini-Mental State Examination (MMSE), and Global Deterioration Scale were assessed. A convenience panel of 9 Canadian specialists experie nced in the treatment of AD provided their opinions on the clinical importa nce of the trial results. Chart review was performed to identify specific b ehaviors that improved, and cost implications of improvements were assessed . Results: The panel determined that statistically significant differences in scores on all scales except the MMSE were likely associated with functiona l or cognitive differences that were clinically relevant for patients, refl ecting stabilization that would have beneficial consequences for caregivers and health care resource use. Subsequent chart review showed that improvem ent on specific scale items confirmed the physician panel's opinion. Analys is of possible cost implications to society indicated that medication expen ditures would be offset largely by delays in the need for paid home care an d institutionalization, positive effects on caregiver health, and less time lost from work for the caregiver. Conclusions: From the perspective of a Canadian specialist panel, rivastigm ine treatment for AD produces clinically relevant effects for patients that are beneficial to caregivers. These effects suggest decreased use of careg iver resources and delays in the need for institutionalization, both of whi ch reduce societal costs.