P1332VASCULAR ACCESS IN OLDER ADULTS: MOSCOW REGION REGISTER ANALYSIS
Authors: Zulkarnaev Aleksei , Stepanov Vadim , Vatazin Andrey , Strugaylo Ewgenii , Fominykh Natalia , Rogozin Vasily 
Published: June 2020

Abstract

Background and Aims
For many years we observed aging of HD population: the proportion older adults is increasing. These patients have extremely low kidney transplantation rate, so vascular access is not a temporary option, but an important factor until the end of life. At the same time in older adults life expectancy is lower and the risks of cardiovascular events are much higher than in the general population of HD patients. We analyzed the results of providing elderly patients with vascular access.

Method
The study included 618 patients (age ≥ 65) from the Moscow region CKD patients register.

Results
With the current practice, only about 60% of elderly patients begin HD within a year after the AVF creation (taking into account competing events) - fig. 1. The proportion of patients with brachiocephalic AVF was significantly higher than in younger patients: 41,3% vs. 16,4%. It is known that proximal AVF have a much greater tendency to increase the volume blood flow (and therefore – cardiopulmonary recirculation) than distal. Thus, elderly patients begin HD with a more adverse comorbid background. Therefore, elderly patients have an additional risk factor - the onset of HD after 65 years – fig 2. Paradoxically, but according to our data, patients who started HD after 65 years had a worse prognosis than patients who reached 65 while already on HD. At the same time, the onset of HD with CVC with the subsequent successful conversion to AVF was not associated with a significant increase in the risk of death («CVC-AVF» factor). Only if CVC remained the only vascular access («CVC» factor), the risk of death is increase significantly. This is indirect evidence in favor of the fact that in elderly patients, the AVF must be created closer to the expected start of HD.
In adjusted model, the significant risk factors also were diabetes, systemic diseases (factor «Other») and comorbidity (CIRS score), but not age.
Among patients who started HD with CVC, all patients received functional AVF or died within 11 months – fig. 3. Infections occur with the same frequency (CVC-AVF vs. AVF) and clinical manifestations of central venous insufficiency do not have time to occur during the expected life period in most patients: incidence rate ratio IRR 1.21 [0.91; 1.31] and IRR 1.11 [0.93; 1.19], respectively.
Is a conversion of AVF to CVC can improve the outcomes in older adults? In some patients probably - yes.
Since many elderly patients initially have heart failure and a reduced cardiac output (CO), the potential for compensating of AVF blood flow (Qa) is significantly less than in younger patients. We found that this leads to the fact that in the elderly, at a lower Qa value, a greater value of cardiopulmonary recirculation is noted. Even with a Qa value of 1.0-1.2 l/min, the Qa/CO value can reach ≈ 25%, which is associated with a significant risk of death. But there is good news: in the older adults some criteria are more informative than in the general population of HD patients: AUC-ROC of ejection fraction (EF), estimated pulmonary artery systolic pressure (ePASP) and Qa/CO – 0.821, 0.804 and 0.846, respectively vs. 0.654, 0.726 and 0.764. The bad news: the decision to convert from a functional AVF to a CVC is a very difficult choice. Specific indications are still not determined. We believe that it is necessary to consider the conversion from AVF to CVC in a case of decompensated heart failure, with EF&lt;30-33% or ePASP&gt;50-55 or Qa/CO&gt;20-25%, if the reduction of Qa does not improve these parameters. In this case, conversion from CVC to AVF may improve the prognosis. Older patients require more careful monitoring than younger patients.

Conclusion
1. The start of HD with CVC is not a problem in case of subsequent successful conversion to AVF. 2. The most important risk factors is comorbidity, starting of HD after 65 years, diabetes and only then - vascular access type. 3. Given all the facts, in the older adults we tend to create an AVF closer to start of HD than in the general HD population.