**4.1 UI definition**

The concept of UI can be based on:


The ICS definitions and terminologies of UI according to the above descriptions have been revised several times (Abrams et al., 1988, Abrams et al., 2002, Haylen et al., 2010). The current definition of UI symptoms is "Complaint of involuntary loss of urine" (Haylen et al., 2010). In the 2002 definition, UI symptoms were not enough to set the UI diagnose; UI signs were needed. Today the majority of studies on UI define UI according to UI symptoms. Studies on UI have used the definitions at the time. As definitions change, prevalence estimates will also change.
