New Study Identifies 24 Harmful Prescription Drug Sequences in Adults

A new study published in the journal BMJ has identified 24 common and potentially harmful "prescription cascades" in adults, where one medication is prescribed to treat the side effect of another. The research, led by Dr. Paula Rochon from the University of Toronto, mapped these event sequences for the first time using population-wide data from Ontario, Canada. Rochon, who coined the term "prescription cascade" nearly 30 years ago, noted that these sequences are often missed in clinical practice.

The study began with a panel of 12 international experts, including researchers from Israel, who compiled an initial list of 65 potential prescription cascades. Each potential cascade was then analyzed against prescription data for the entire population of Ontario, based on three criteria: the prevalence of the first drug, the frequency of the second drug being prescribed alongside it, and the strength of the association between the two. Only 24 sequences met all three criteria, indicating they are not just theoretical scenarios but actual patterns observed in millions of prescriptions.

A common example cited is the use of NSAIDs (non-steroidal anti-inflammatory drugs) for pain relief, which can elevate blood markers. When these markers rise, a patient might be prescribed a new medication to balance them, without always investigating if the NSAID was the original cause. The researchers emphasize that the study identifies these sequences in data but does not definitively prove that the second drug was prescribed solely due to the first in every individual case, as alternative explanations may exist.

The findings are particularly relevant to Israel due to its healthcare system structure, where older adults may interact with multiple physicians. This can lead to a fragmented view of a patient's medication list, making prescription cascades more likely. The study suggests that patients should maintain updated medication lists and inquire with their doctors whether a new prescription is for an independent issue or a side effect of existing medication.

The economic implications are also significant, as each additional medication adds costs to the healthcare system and increases the risk of further side effects, potentially leading to more prescriptions. The study's methodology and findings provide a structured approach to a known issue of polypharmacy in the elderly.