Three studies included in this review did not report any data on direct or indirect cost [27,44,46]. Goodman et al. (2011) [27] focused on the out-of-pocket expenses and insurance costs directly related to the treatment of BPD (i.e. therefore categorised as intervention costs in this review). In addition, Prendergast & McCausland (2007) [44] and Richter and colleagues (2013) [46] did not provide the actual (in)direct costs for inpatient and/or outpatient treatment in the paper, only cost-savings of providing DBT compared to TAU were provided (i.e. cost offset PT vs. TAU).