Association between different anticholinergic drugs and subsequent dementia risk in patients with diabetes mellitus

BACKGROUND The effects of oxybutynin, solifenacin and tolterodine on dementia risk in patients with diabetes mellitus (DM) remain unknown. We investigated the effects of oxybutynin, solifenacin and tolterodine on dementia risk in patients with DM. METHODS We conducted a cohort study by using the diabetes dataset of the Taiwan National Health Insurance Research Database from 1 January, 2002 to 31 December, 2013. We included 10,938 patients received one type of oxybutynin, solifenacin, or tolterodine, while 564,733 had not. We included a comparable number of patients not receiving oxybutynin, solifenacin, or tolterodine as controls through systematic random sampling matching by age, gender, and the year of the index date with 1 to 1 ratio. The dementia risk was estimated through multivariate Cox proportional hazard regression after adjustment for several confounding factors. RESULTS The dementia event rates were 3.9% in the oxybutynin group, 4.3% in the solifenacin group, 2.2% in the tolterodine group and 1.2% in the control group (P<0.001). The adjusted HRs compared to nonusers of anticholinergic drugs were 2.35 (95% CI, 1.96 to 2.81), 2.16 (95% CI, 1.81 to 2.58), and 2.24 (95% CI, 1.85 to 2.73), respectively, for patients receiving oxybutynin, solifenacin, or tolterodine. CONCLUSION Our study indicates an association between taking oxybutynin, solifenacin and tolterodine and the subsequent diagnosis of dementia in DM patients. Moreover, the patients using oxybutynin had highest risk. The impact of these three drugs on risk of dementia in non-diabetic populations is warrant.