Frequency of and factors related to pro re nata (PRN) medication use in aged care services

Little is known about the contribution of 'pro re nata' (PRN) medications to overall medication burden in residential aged care services (RACS).

To determine the frequency of, and factors associated with PRN medication administration in RACS.

Details of all medications charted for regular or PRN use were extracted from medication charts for 383 residents of 6 Australian RACS. Records of medications administered over a 7 day period were also extracted. Factors associated with PRN medication administration among residents charted ≥1 PRN were determined using multivariate logistic regression.

Of the 360 (94%) residents charted ≥1 PRN medication, 99 (28%) were administered PRN medication at least once. The most prevalent PRN medications were analgesics and laxatives. Residents with greater dependence with activities of daily living (ADL) (adjusted odds ratio (aOR) per additional point on Katz ADL scale: 0.80; 95% confidence interval (CI) 0.72-0.89; p < 0.001) and a greater number of regular medications (aOR per additional medication: 1.06; 95% CI 1.00-1.13; p = 0.042) were more likely to be administered PRN medication.

Although most residents are charted PRN medications, rates of administration are relatively low, suggesting the contribution of PRNs to medication burden in RACS may be lower than previously thought.