Frequency of medication errors in primary care patients with polypharmacy

Chronic diseases affect more than half of the population ≥75 years of age in developed countries. Prescription medication use increases with age. Depending on definition, 25-80% of elderly are exposed to polypharmacy. Polypharmacy increases the risk of hospitalization, interactions and adverse drug reactions.

To examine the frequency of medication errors in patients with polypharmacy treated in general practice.

The medications of 169 patients with polypharmacy treated in 22 GP surgeries in Austria were analysed. The analysis identified (i) medication errors, including non-evidence-based medications, dosing errors and potentially dangerous interactions in all patients and (ii) potentially inappropriate medications (PIMs) in the subgroup of elderly patients (≥65 years).

The patients took on average 9.1±3.0 medications per day. The maximum, in one patient, was 20 medications per day. Some 93.5% had at least one non-evidence-based medication. On average, 2.7±1.66 medications per patient were found to be not indicated. At least one dosing error was found in 56.2% of all patients. One potential interaction of the most severe degree (category X interaction) was detected in 1.8% (n = 3) and two such interactions in 0.6% (n = 1). These combinations should have been avoided. Of the 169 patients, 158 were elderly (≥65 years). Of these seniors, 37.3% (n = 59) had at least one PIM according to the PRISCUS list for the elderly.

The frequency of medication errors is high in patients with polypharmacy in primary care. Development of strategies (e.g. external medication review) is required to counteract medication errors.