Prescribing Cascades Among Older CommunityDwelling Adults: Application of Prescription Sequence Symmetry Analysis to a National Database in Ireland

PURPOSE Prescribing cascades occur when one medication is used to treat adverse effects of another medication. Older adults with polypharmacy are at higher risk for this phenomenon. We examined the prevalence, magnitude, and effect modification of 9 prescribing cascades (ThinkCascades) among older community-dwelling adults in a national prescription database. METHODS We used prescription sequence symmetry analysis to examine prescriptions for ThinkCascades medications dispensed in primary care under the General Medical Services scheme in Ireland. Analyses were based on prescriptions dispensed between 2017 and 2020 among 533,464 adults aged 65 years or older. Incident users of both medications in each ThinkCascades dyad were included. We used an observation window of 365 days and examined other windows in sensitivity analyses. Adjusted sequence ratios (aSRs) took into account secular prescribing trends. We also conducted analyses stratified by sex, age, and individual index medication. RESULTS Five prescribing cascades had significant positive aSRs, indicating that the patient was more likely to receive the index medication before the marker medication. The largest signal was identified for the calcium channel blocker to diuretic cascade (prevalence, 2.6%; aSR = 1.93; 95% CI, 1.79-2.09). Positive signals were also identified for the α₁-receptor blocker to vestibular sedative cascade (prevalence, 3.0%; aSR = 1.63; 95% CI, 1.46-1.81); the selective serotonin reuptake inhibitor/selective norepinephrine reuptake inhibitor to sleep medication cascade (prevalence, 2.5%; aSR = 1.54; 95% CI, 1.40-1.69); the antipsychotic to antiparkinsonian cascade (prevalence, 0.4%; aSR = 1.20; 95% CI, 1.00-1.43); and the benzodiazepine to antipsychotic cascade (prevalence, 3.2%; aSR = 1.15; 95% CI, 1.08-1.21). CONCLUSIONS To our knowledge, this study is the first to describe the prevalence of an expert consensus–based list of prescribing cascades, ThinkCascades, in a national population of older adults, and it identified 5 clinically relevant prescribing cascades. These findings highlight prescribing cascades as an important underresearched area contributing to complex polypharmacy among older people living with multimorbidity.