Multimorbidity and Cardiovascular Risk Factors After Renal Transplant

1. BACKGROUND

At the end of 2022 39,874 adult patients in the UK were living with a kidney transplant, representing 56.2% of the population on kidney replacement therapy. Kidney transplant remains the gold standard of renal replacement therapy and confers benefits in survival and quality of life over dialysis2. Short term survival post-transplant is good, with 94% adjusted 5 year survival in the UK for a transplant from a living donor and 87% for a deceased donor from the most recent UK renal registry data1.

A high proportion of renal transplant patients have a high burden of comorbidities. Increasing multimorbidity has been shown in the general population to increase risk of premature death and hospital admissions and is associated with poorer function and greater economic costs. Much of the data in kidney transplant recipients focusses on comorbidity burden at time of transplant and the predictive use of this data for outcomes. There is little available data on the patterns and progression of multimorbidity for patients living with renal transplant. An assessment of the wider CKD cohort was undertaken using medical records and self reporting to understand multimorbidity, with a group of 176 transplant patients in the UK and showed that 92% had at least one comorbidity in addition to CKD. The most common comorbidity was hypertension (60.1%), followed by musculoskeletal conditions (40.9%) and then cardiovascular disease and diabetes. However, there is no data available, in this study or others, on the longitudinal development of comorbidities after transplant receipt. There is also no data available on the impact of multimorbidity on the quality of life of kidney transplant recipients. Although there is evidence for development of specific conditions, this has not been examined within the context of multiple long term health conditions.

There is no consensus on the measurement of multimorbidity, and no consensus on which comorbid conditions should be used in a count. Expert reviewers suggest the conditions used to define multimorbidity should be guided by health impact and may be tailored to a study population. No such work has taken place in the kidney transplant population.

A major comorbidity at time of transplantation and in post transplantation is cardiovascular disease and this is a major cause of death for patients with a renal transplant. Although the risk of adverse cardiovascular outcomes is decreased compared to patients on dialysis it is significantly increased compared to the general population. In addition, there is a high prevalence of both hypertension and diabetes within the transplant population. As well as these being common comorbidities to have at time transplant, patients commonly develop post-transplant diabetes. Alongside these factors, the risk of cardiovascular disease is also increased by raised BMI and lipid levels, which are commonly raised in renal transplant patients. The interaction between these risk factors and transplant specific factors such as immunosuppressive medication and post-transplant weight gain contribute to significant cardiovascular risk. There is no consensus on specific post-transplant treatment targets or interventions. Much of the evidence available for the timeline of development of cardiovascular risk factors is limited to retrospective cohort data and does not place cardiovascular disease within the context of multimorbidity6. In addition, much of the data predates current immunosuppression strategies and cardiovascular management strategies.