Prescribing cascades in older adults with and without dementia
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PROJECT SUMMARY / ABSTRACT Background: In older adults, individual prescribing decisions may appear reasonable in isolation yet can lead to a tangled web of complications. A key exemplar of this is prescribing cascades. These occur when a medication causes an adverse effect, and rather than changing the offending drug, a second medication is given to manage the symptoms. This in turn may cause more adverse effects that are managed with a third medication, and so forth. While relevant for all older adults, cascades may be particularly common and harmful in people with dementia, in part because communication challenges may increase the risk that clinicians will not recognize that an adverse drug effect has occurred, and instead interpret new signs or symptoms as the manifestation of an underlying disease. Although prescribing cascades are likely common and can confer substantial morbidity, there has been remarkably little scholarship on this topic. In this proposal we will explore two potential cascades that are models of this problem: (A) gabapentin and pregabalin peripheral edema loop diuretics, and (B) loop diuretics urinary symptoms medications used to treat urinary symptoms. Aims: (1) To determine the prevalence and risk factors for a prescribing cascade involving gabapentinoids and loop diuretics, and how these differ between older adults with and without dementia; (2) To determine the prevalence and risk factors for a prescribing cascade involving loop diuretics and urinary symptom medications, and how these differ between older adults with and without dementia; (3) To characterize the pathways through which the gabapentinoid-loop diuretic cascade occurs in these populations. Methods: Using national data from VA and Medicare, for Aims 1 and 2 we will assemble a retrospective cohort of older adults who were non-users of both the index medication (the one that starts the cascade) and the outcome medication (the one used to treat adverse effects caused by the index medication). We will then identify which subjects subsequently started the index medication and which did not start the index medication but instead started another type of medication (i.e., a control group). We will compare use of the outcome medication between these groups using multivariable time-to-event approaches that account for competing risks. Interaction terms and stratified analyses will be used to compare outcome rates and risk factors among people with and without dementia. For Aim 3, we will conduct chart review on 500 subjects (250 with dementia and 250 without) with the gabapentinoid-loop diuretic cascade and evaluate elements of decision-making that contributed to the cascade. The proposed research will provide tremendous opportunities for mentoring junior investigators and supporting the mentoring aims of this K24 award. Relevance / public health significance: Understanding prescribing cascades and the patterns of decision- making that lead to them will inform strategies to prevent and mitigate these potentially harmful practices.
