Objective: The objective of this study was to assess changes in healthcare costs between patients treated with rivastigmine and an untreated comparison group using data from the California Medicaid (“Medi-Cal”) program.
Design: This study used a retrospective cohort design.
Materials and Methods: We employed administrative claims and eligibility data for a 20% random sample of Medi-Cal recipients to examine Medicaid expenditures among patients prescribed rivastigmine versus an untreated comparison cohort. Study patients included adults aged 50+ years of age who were in an outpatient setting at index. Patients in the rivastigmine cohort were treated between July 1, 2000 and March 31, 2001 ("index period") and had no acetylcholinesterase inhibitors (AChEIs) prescribed in the prior 6 months. The dispense date of the first prescription for rivastigmine was set as their index date. The comparison cohort included all patients who did not receive AChEIs anytime during the study period and had at least 1 diagnosis for Alzheimer’s disease (AD) in the index period. The date of the first AD diagnosis was set as their index date. The mean change in Medicaid expenditures from 6 months before to 6 months after each patient’s index date was assessed between cohorts. The Wilcoxon rank test was used to evaluate the statistical significance of differences in costs between study cohorts; multivariate regression analyses, adjusting for differences between cohorts in age and gender, yielded similar results.
Results: In total, 371 patients met the criteria for study inclusion; 76 in the rivastigmine cohort and 295 in the comparison group. The comparison cohort was somewhat older (81 vs. 75 years) and more likely to be female (83% vs. 72%). The mean Charlson comorbidity index was similar between groups (1.0). Healthcare costs increased in both cohorts between the 6 month pre-index and 6 month post-index periods. Relative to the comparison group, pharmacy costs increased by $707 (p< 0.05) more in the rivastigmine cohort; about two-thirds of the increase ($478) was due to AChEIs. However, the additional pharmacy costs were more than offset in terms of savings in medical costs ($1,050, p<0.05), resulting in a six-month average savings of $343 per patient.
Conclusion: Rivastigmine therapy appears to be associated with a reduction on overall Medicaid expenditures, a finding that is likely to be of interest to state Medicaid program administrators.
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