A medication capture and analysis system for use in epidemiology.

Epidemiological studies of elderly people have tended to avoid estimations of medication prevalence and adverse effects, partly because of the practical difficulties of capturing medication data and then rendering them analysable. This article describes a versatile coding system for medication data entry that greatly simplifies the process of medication analysis in epidemiological field studies. Five-digit numerical codes are used to identify individual preparations, and the system's hierarchical nature allows aggregation to a number of levels. To date, the MedCap (Medication Capture) system has been used successfully in 3 different ways in 2 major longitudinal studies of elderly people in Australia, and offers a possible solution to the practical difficulties of field pharmacoepidemiology.