Prescribing Cascades

A prescribing cascade begins when a drug is prescribed, an adverse drug event occurs that is misinterpreted as a new medical condition, and a subsequent drug is prescribed to treat this drug-induced adverse event. This concept can be expanded to link prescription drug therapy to development of new medical conditions that are managed with OTC therapies, supplements, or medical devices:

Source: Rochon et al. Lancet. 2017

These cascades often involve whole drug classes, encompassing a multitude of agents:

Source: Rochon et al. Lancet. 2017

Prescribing cascades most commonly occur when multiple drug therapies are used on a chronic basis, particularly in older patients. Most concerning is when a new symptom identified in an older person is falsely attributed to a new medical condition instead of a drug-related adverse event, and then results in the initiation of a new, unnecessary drug therapy.

EMRs could alert prescribers to potential prescribing cascades at the time of prescribing decisions, but at present tend to focus more on potential drug-drug interactions. As such, providers should be vigilant in identifying and interrupting prescribing cascades by routinely reflecting on 3 specific questions: 

  1. Is a new drug being prescribed to address an adverse event from a previously prescribed drug therapy? Before starting a drug therapy to treat a new medical condition, consider whether this condition could be a drug-related adverse event. 
  2. Is the initial drug therapy that led to the prescribing cascade really needed? (i.e., was the initial drug therapy absolutely necessary, could the initial drug be substituted for a safer alternative, or could the dose be reduced and therefore reduce the need for subsequent drug therapy?)
  3. What are the harms and benefits of continuing the drug therapy that led to the prescribing cascade? Consider the risks and benefits with the patient via the shared decision-making process.
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