The first step to addressing problems of irrational use of medicines is to measure the problem, analyse it and understand the causes underlying it. There are four main methods, all of which should be regularly used by DTCs.
• Aggregate data methods involve data that do not relate to individual patients and can be collected relatively easily. Methods such as ABC analysis, VEN analysis and DDD methodology are used to identify broad problem areas in drug use.
• Drug indicators studies involve collecting data at the level of the individual patient but do not usually include sufficient information to make judgements about drug appropriateness for diagnosis. Such data can be collected by non-prescribers and can be used to identify problem areas in medicine use and patient care, and evaluate interventions designed to correct the problems identified.
• Qualitative methods such as focus group discussion, in-depth interview, structured observation and structured questionnaires are useful for identifying why drug use problems occur.
• Drug use evaluation is a system of ongoing criteria-based evaluation of drug use that will help to ensure appropriate use at the individual patient level. This method involves the detailed analysis of individual patient data.