#3159 IMPACT OF MENTAL ILLNESS ON POST-TRANSPLANTATION OUTCOMES IN NEW ZEALAND: THE ASSET-MH DATA LINKAGE STUDY
Authors: Mata Nicole De La , Cross Nicholas , Dunckley Heather , Cutting Rachel , Beaglehole Ben , Dittmer Ian , Irvine John , Walker Curtis , Jones Merryn , Wyld Melanie , Wyburn Kate , Webster Angela 
Published: June 2023

Abstract

Background and Aims
People with severe mental illness are 6 times more likely to develop kidney disease. Mental illness is overrepresented in the kidney failure population. Up to 40% of dialysis patients are affected by depression and anxiety. There is limited understanding of the extent and impact of mental illness on transplant outcomes. We aimed to evaluate the impact mental illness has upon post-transplant outcomes, including graft failure and death in kidney transplant recipients in New Zealand.

Method
We included all incident kidney transplant recipients in New Zealand, 2006-2019 from the ASSET linked data platform, including Australian and New Zealand Dialysis and Transplant Registry, and national health registries (eg. hospitalisations, prescriptions and mental health services). Presence of mental illness was ascertained based on past use of medications (antipsychotics and antidepressants) and mental health services (community/residential support and inpatient) occurring at least twice over a year. Follow-up was from transplantation until death, graft failure or 31st Dec 2019. We used Cox models to evaluate risk of graft failure or death for mental health users compared to non-mental health users, adjusting for age, sex, calendar year and prior dialysis time.

Results
We included 1,796 kidney transplant recipients, where 457 (25%) had mental illness comorbidity. Overall, 228 (13%) used medication for mental illness (25 antipsychotics; 203 antidepressants) and 340 (19%) used mental health services (327 community/residential support; 14 inpatient). There were 111 recipients (6%) who had used medications and services for mental illness. There were 42 (9%) graft failures and 34 (7%) deaths among those with mental illness compared to 137 (10%) graft failures and 125 (9%) deaths among those without mental illness. Those with mental illness had the same risk of graft failure compared to others (p = 0.17), regardless of whether they used antidepressants (HR: 1.52, 95%CI: 0.93-2.48, p = 0.09) or received community/residential support (HR: 1.19, 95%CI: 0.78-1.81, p = 0.42). There were no graft failures among those using antipsychotics or receiving inpatient care. Risk of death increased 3-fold (HR: 3.24, 95%CI: 1.51-6.99, p &lt; 0.01) in those using antipsychotics compared to those without mental illness, but was not increased among those using antidepressants (HR: 0.90, 95%CI: 0.47-1.72, p = 0.74). There was weak evidence for an increased risk of death among those receiving community/residential support (HR: 1.57, 95%CI: 0.99-2.49, p = 0.06) compared to those without mental illness. Risk of death was not significantly associated with those receiving inpatient care (HR: 3.00, 95%CI:0.72-12.42, p = 0.13), although event rates were low. For composite of graft failure or death, those with mental illness had the same risk as those without (p &gt; 0.10), regardless of receiving antipsychotics (HR: 1.77, 95%CI: 0.83-3.75) or antidepressants (HR: 1.23, 95%CI: 0.84-1.82), or community/residential support (HR: 1.37, 95%CI: 1.00-1.87) or inpatient care (HR: 1.41, 95%CI: 0.35-5.71).

Conclusion
Mental illness comorbidity is common in this setting, with one in ten transplant recipients in New Zealand receiving psychiatric treatment. Antipsychotic use was associated with three times the risk of death. Otherwise, those with mental illness had comparable post-transplant outcomes. There is opportunity for more collaborative psychiatric and transplant services to promote better patient outcomes and reduce post-transplant mortality.