Pill-count and the arithmetic of risk: Evidence that polypharmacy is a health status marker rather than a predictive surrogate for the risk of adverse drug events.

With advancing age there is an increase in the disease burden and thus in the number of drugs prescribed to this patient group. It is often assumed that an increase in pill count is associated per se with an increase in the number of medication errors (e.g., potentially inappropriate prescribing, PIP) and the frequency of adverse drug events (ADE). However, prescribing more drugs can also mean more successful treatment, making it important to critically assess the benefit/risk balance of the medications prescribed in each patient. Whether a prescribed medication is appropriate depends on the clinical state of the patient (diagnoses), treatment goals, comedication/drug interactions, patient preferences, whether the patient tolerates the drug, a measure of how frail the patient is, etc. It is often argued that the number of prescribed drugs should be restricted, but we hold the view that this should only be done after careful consideration of the factors mentioned above. In our study, we remodeled the findings of two large cohort studies investigating the association between the number of drugs prescribed and clinical endpoints. The graphic illustrations obtained confirmed that targeting pill count, as a measure to reduce ADEs and mortality, fails to impact patient well-being because the number of drugs prescribed is likely determined by patient characteristics affecting drug response, namely, disease burden, patient functionality, and specific patient needs, all of which must be taken into account in order to reduce the risk of PIMs and the occurrence ADEs.
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