The impact of treatment-resistant depression on the lives of carers: A mixed-methods study

Introduction: The lived experiences of informal carers of people with depression, particularly those with treatment-resistant depression (TRD), are rarely explored, despite their vital supportive role. Methods: This mixed-methods study explored the quality of life (QoL) and experiences of carers of individuals with symptomatic TRD (Carers-Sym-TRD; n = 79) or in remission post-TRD (Carers-Rem-TRD; n = 20). Participating carers completed quantitative surveys measuring health-related and broader QoL (EQ-5D-5L/ WHOQOL-BREF) and work productivity/activity impairment (WPAI:MM-CG). Interviews were also conducted with 12 Carers-Sym-TRD and 11 Carers-Rem-TRD and analysed thematically. Results: Carers-Sym-TRD had impaired QoL compared with Carers-Rem-TRD, with significantly lower EQ-5D-5L index values (median = 0.84/1.00, respectively; p = 0.020) and WHOQOL-BREF overall score (median = 63.0/ 70.1; p < 0.001), physical health (median = 15.3/17.3; p < 0.001), psychological health (median =13.3/14.7; p = 0.017), social relationships (median = 13.3/14.7; p = 0.017) and environment (median = 14.5/16.5; p = 0.011) domain scores. Work productivity/activity impairment was greatest in Carers-Sym-TRD across most WPAI:MM-CG domains, with a higher degree of impairment reported on the presenteeism and work productivity domains, however, there were no significant differences between the carer groups. Interview data suggested that impacts on carers' psychological/emotional wellbeing led to physical problems, which affected cognition and daily performance; Also, successful treatment for the person with depression helped carers worry less and reclaim their independence. Limitations: Recruitment challenges limited the Carers-Rem-TRD sample; clinical validation of the patient's depression diagnosis was not confirmed for all carers. Conclusions: TRD has an extensive adverse impact on carers' lives. Carers-Sym-TRD had significantly impaired QoL across a variety of domains compared with Carers-Rem-TRD, suggesting that achieving remission not only benefits patients but also those who care for them.