Elderly patients were very knowledgeable about how to use the PCA device but not about how often they could receive PCA medication. This lack of knowledge may have influenced how often they requested pain medication, because almost 90% of patients received less than 25% of the PCA allowable medication dose. This low usage of PCA medication delivery calls into question the cost-effectiveness of this method of medication delivery for the elderly. Additional studies are needed to verify these findings in other elderly patients.