Issue	Method
Unit of analysis issues/cross‐over trials	Data from randomised cross‐over studies up to the point of first cross‐over were eligible for inclusion. We excluded data from subsequent phases. Due to the characteristically unstable course of BPD, it did not seem appropriate to us that participants served as their own controls (within‐subject comparisons). However, we would have used first phase data up to the point of first cross‐over for those studies and applied the inverse variance methods as recommended by Elbourne 2002.
Search methods for identification of studies	Contact psychotherapeutic associations directly in order to identify any published and upcoming research.