Comparison of existing polypharmacy measures to a measure incorporating all modes of administration: an…

Cohort studyInternational journal of clinical pharmacy· Jul 2026

Comparison of existing polypharmacy measures to a measure incorporating all modes of administration: an observational study using routinely collected data.

David Lim, David Youens, Rachael Moorin, Andrew Stafford

GeriatricsCohort studyClinical practiceQ1IF 3.3

Counting non-oral medicines raised measured polypharmacy (5+ drugs) prevalence by 4.0%.

Comparison of existing polypharmacy measures to a measure incorporating all modes of administration: an observational study using routinely collected data.

David Lim … Andrew Stafford

International journal of clinical pharmacy · Jul 2026

Background

Polypharmacy is often associated with adverse clinical outcomes and increased medication management complexity.

Purpose

This study compared traditional measures of polypharmacy with a measure incorporating all modes of medicine administration and examined how these differences impacted estimates of polypharmacy prevalence among adults aged > 65 years in Western Australia (Western Australia) from 2012/13 to 2018/19, between two independent cohorts: community-dwelling and residential aged care home populations.

Methods

Linked medication dispensing data were used to classify and compare medicines between community-dwelling and residential aged care populations in Western Australia.

4.0%

Results

4.0%

counting non-oral forms reclassified more patients into the 5+ medicine group

More results

Inclusion of medicines via mode of administration increased observed medicine burden in both subpopulations, with a greater relative increase in residential aged care.

This approach notably contributed to total medicine counts, revealing previously unrecognised medicine exposure.

More results

Drugs for dry eyes also emerged as the 7th most common medicine class, with only minor ranking changes observed for the other top medicine classes.

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Conclusion · 1 of 2

Incorporating all modes of medicine administration into a polypharmacy measure substantially altered estimates of medicine burden and identified previously unrecognised exposure, particularly among residential aged care populations.

Conclusion · 2 of 2

The impact was greatest in higher polypharmacy categories, indicating that conventional approaches may underestimate medicine use in individuals with more complex therapeutic regimens.

Comparison of existing polypharmacy measures to a measure incorporating all modes of administration: an observational study using routinely collected data.

Comparison of existing polypharmacy measures to a measure incorporating all modes of administration: an observational study using routinely collected data.

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