An examination of three prescribing cascades in a cohort of older adults with dementia

Background Prescribing cascades are a source of inappropriate prescribing for older adults with dementia. We aimed to study three prescribing cascades in older Nova Scotians with dementia using administrative databases. Methods Cohort entry for Nova Scotia Seniors’ Pharmacare Program beneficiaries was at the date of dementia diagnosis. Prescription drug dispensation data was extracted for inciting medication and second treatment (cholinesterase inhibitor and bladder anticholinergic, metoclopramide and Parkinson’s disease medication, or calcium channel blocker (CCB) and diuretic) over the six-year period from April 1, 2009 to March 31, 2015. In three separate analyses, dispensation of an inciting medication signaled a look back of 365 days from the date of first dispensation to confirm that the second treatment was started after the inciting medication. The prescribing cascade was considered when second treatment was started within 180 days of the inciting treatment. Sex differences in the prescribing cascade were tested using t-tests or chi square tests as appropriate. Both univariate (unadjusted) and multivariate (adjusted) logistic regression (adjusted for age, rurality, and sex) and Cox proportional hazards regression was used to identify risk factors for the prescribing cascade. Results In the period from March 1, 2005 to March 31, 2018 28,953 Nova Scotia Seniors Pharmacare beneficiaries with dementia (NSSPBD) were identified. There were 60 cases of bladder anticholinergics following cholinesterase inhibitors, 11 cases of Parkinson’s disease medication following metoclopramide, and 289 cases of a diuretic following CCB. Regression analysis demonstrated that risk of bladder anticholinergics following cholinesterase inhibitors and diuretics following CCBs were associated with female sex. Cox regression analyses suggested that bladder anticholinergics were less often used by those on cholinesterase inhibitors but did not identify CCB use as leading more frequently to diuretic use. Conclusions Of the three prescribing cascades investigated, diuretics following CCB was the most common and bladder anticholinergics following cholinesterase inhibitors the second most common. Both these prescribing cascades were more common for women suggesting clinicians need increased attention to monitor for prescribing cascades among women.