Effect of drug compliance on health care costs in newly-diagnosed dementia: a nation-wide analysis

Background The cost-effectiveness of both cholinesterase inhibitors and memantine by delaying nursing home placement has been supported by numerous studies. The importance of sustained pharmacological treatment in dementia has been relatively less recognized by public health policies compared to early diagnosis. We investigated the effect of the drug (donepezil, rivastigmine, galantamine, and memantine) compliance on the health care costs in newly-diagnosed dementia. Methods National Health Insurance Service (NHIS) database which covers the entire population of South Korea was used for analysis. Health care expenditure of patients newly-diagnosed with dementia in between 2012 and 2014 was investigated for 3 to 5 years. For drug compliance, we used Medication Possession Ratio (MPR) that indicates the percentage of time a patient has access to medication. Multivariate linear regression analysis including generalized estimated equation and gamma distribution was used for statistical analysis. Results We identified 252,594 patients who were both prescribed with cognitive enhancers and newly diagnosed with dementia. When initial MPR increased 20%, total health care costs decreased 8.4% (RR = 0.916, 95%; CI 0.914 to 0.916). Same relationship was shown with medical costs related to dementia, admission to a general hospital, and emergency room visits. When MPR increased 20% compared to the previous year, the total health care costs, admission to a general hospital, emergency room visits, and admission to a nursing hospital decreased. Conclusions This population-based retrospective cohort study provides evidence that patients newly-diagnosed with dementia who showed higher initial drug compliance or maintained antidementia drugs (Cholinesterase inhibitors and memantine) would benefit in total health-care costs. Key messages Public health care policies should not only focus on early diagnosis in dementia, but also recognize the importance of adherence to cognitive enhancers. To maximize the positive pharmacoeconomic effect of early diagnosis of dementia, it is important to sustain adequate drug compliance to cognitive enhancers.