Older Australians' medication use: self-report by phone showed good agreement and accuracy compared with home visit

To ascertain the accuracy of telephone-interview method for measuring older people's medication use ("self-report by phone") by determining agreement between results from this method and from a home visit ("home inventory").

An agreement study involving community-dwelling patients aged more than 65 years, selected from four general practices in the Hunter Region of Australia. Commonly used classes of drugs were selected for comparison.

Of 154 patients, 14 participants were ineligible, because they had hearing problems (9) or did not use any medicines (5). The response rate was 70% (98 of 140). The observed overall agreement and prevalence-adjusted and bias-adjusted kappa coefficients were very high for all prescribed drug categories, but lower for over-the-counter (OTC) and complementary medicines. Specificity of the self-report by phone compared with home inventory was consistently high across all drug classes. Sensitivity values were more than 89% for all drug classes but were lower for OTC and complementary medicines (74%) and paracetamol (78%). Similar patterns were found for negative predictive values. Positive predictive values were lower for drugs used on an as-needed basis.

Measuring patient's medication use by telephone is an accurate and relatively inexpensive alternative to home-inventory methods, and has merit for use in future studies of older patients' drug use.