'What is not written does not exist': the importance of proper documentation of medication use history.

Medications are perceived as health risk factors, because they might cause damage if used improperly. In this context, an adequate assessment of medication use history should be encouraged, especially in transitions of care to avoid unintended medication discrepancies (UMDs). In a case-controlled study, we investigated potential risk factors for UMDs at hospital admission and found that 150 (42%) of the 358 patients evaluated had one or more UMDs. We were surprised to find that there was no record of a patient and/or relative interview on previous use of medication in 117 medical charts of adult patients (44.8%). Similarly, in the medical charts of 52 (53.6%) paediatric patients, there was no record of parents and/or relatives interviews about prior use of medications. One hundred thirty-seven medical charts of adult patients (52.4%) and seventy-two medical charts of paediatric patients (74.2%) had no record about medication allergies and intolerances. In other words, there was a lack of basic documentation regarding the patient's medication use history. As patients move between settings in care, there is insufficient tracking of verbal and written information related to medication changes, which results in a progressive and cumulative loss of information, as evidenced by problems associated with clinical transfers and medication orders. Proper documentation of medication information during transfer is a key step in the procedure; hence, it should be rightly performed. It remains unclear whether interviews, and other investigations about medication use history have been performed but have not been recorded as health-care data. Therefore, it is crucial to the improvement of medication use safety that documentation of all drug-related information-even if not directly related to the actual event-become routine practice in health-care organizations, since 'what is not written does not exist'.