Definition of treatment-resistant depression - Asia Pacific perspectives

Background: The lack of uniformity in the definition of treatment resistant depression (TRD) within the Asia-Pacific (APAC) region may have implications for patient management. We aimed to characterize the most commonly used TRD definition in selected APAC countries. Methods: A systematic literature review of TRD definitions in APAC countries was conducted in Medline and Embase (2010-2016) and conference proceedings (2014 and 2016). TRD guidelines (APAC, Europe regional, US, or international) were also searched. An expert-panel explored APAC nuances in TRD definitions to achieve consensus for a regional-level definition. Results: Ten guidelines and 89 studies qualified for study inclusion. Among the studies, variations were observed in definitions regarding: number of antidepressants failed (range: (3) 1 to (3) 3), classes of antidepressants (same or different; 59% did not specify class), duration of previous treatments (range: 4-12 weeks), dosage adequacy, and consideration of adherence (yes/no; 88% of studies did not consider adherence). No TRD-specific guidelines were identified. The emerging consensus from the literature review and panel discussion was that TRD is most commonly defined as failure to (3) 2 antidepressant therapies given at adequate doses, for 6-8 weeks during a major depressive episode. Limitations: Few studies provided definitions of TRD used in daily clinical practice, and a limited number of countries were represented in the included studies and expert panel. Conclusion: Attaining consensus on TRD definition may promote accurate, and possibly early detection of patients with TRD to enable appropriate intervention that may impact patient outcomes and quality of life.