Different risk factors affect patency between vascular access construction and the first percutaneous transluminal angioplasty, Mahoko Yoshida (Hiroshima University Hospital, Hiroshima, Japan) and colleagues conclude in the Journal of Vascular Access. Their results indicate that a poor patency rate is commonly associated with advanced age and diabetes mellitus.
“These findings suggest that older patients and those with diabetes mellitus are more likely to experience vascular access problems after both vascular access construction and percutaneous transluminal angioplasty [PTA], and that different risk factors should be taken into account when managing patients undergoing haemodialysis after vascular access construction and PTA,” the study authors write. “Understanding the risk factors that contribute to vascular access problems may lead to better surveillance and focused care in high-risk patients, resulting in more effective management of vascular access.”
Dialysis: “A global health concern”
The number of patients undergoing dialysis worldwide has been increasing each year, the study authors write, and is considered a global health concern. The majority of dialysis patients receive haemodialysis, and are known to suffer from various complications, including cardiovascular disease and infections. The most frequent issue relates to problems with vascular access: stenosis, thrombosis, aneurysm, and infection. “In fact,” Yoshida et al say, “the medical expenses for vascular access-related complications is estimated at JPY 10,953,310,000/year”. The investigators therefore surmise that “recognition of risk factors for vascular access failure is needed not only to improve the quality of life of patients undergoing haemodialysis, but also to reduce medical expenditure”.
They conducted a multicentre, prospective, observational study of 611 patients who had started haemodialysis between 1 April 2012 and 31 March 2018, and investigated the primary and secondary patency rates after construction of a radiocephalic arteriovenous fistula (AVF) and arteriovenous graft (AVG). Primary patency was defined as the period from vascular access construction to percutaneous transluminal angioplasty or surgical revision within 24 months; secondary patency was defined as the period from vascular access construction to the date of vascular access abandonment. The study also examined the patency rate following percutaneous transluminal angioplasty (PTA)—defined as the period from the first PTA to the next PTA or surgical revision within 12 months—as well as the clinical factors that contributed to the development of restenosis. All patients were followed-up until December 2018.
Post-PTA patency unaffected by vascular access form in older patients
The study results reveal that radiocephalic AVF exhibited better 24-month primary and secondary patency rates than AVG in patients who started haemodialysis: 54.5% and 91.6% versus 25.1% and 70.3%. The authors note that these 24-month primary and secondary patency rates after vascular access construction are higher than those reported in the literature by researchers investigating patients outside of Japan. They postulate that the higher patency rates seen in Japanese patients could be due to the fact that they undergo haemodialysis with lower blood flow, which they suggest may enable the vascular access to be used for longer periods.
While the patency rates after vascular access construction between the two vascular access forms (radiocephalic AVF and AVG) was not significantly different in the multivariate analysis, they did show a significant difference in the log-rank test. “With respect to the post-PTA patency rate, although radiocephalic AVF appeared to result in a better patency rate than that of AVG, the difference was not statistically significant in either the log-rank test or Cox proportional hazard model,” Yoshida and colleagues discuss. “A previous study reported that AVF exhibited a better patency rate after both vascular access construction and PTA than AVG. Notably, another study showed that the patency rate of AVF did not differ from that of AVG in advanced-age patients undergoing haemodialysis, especially those aged >65 years. In the present study, the median age of the patients was 70 years, suggesting that rather than the vascular access form, the background of the patients may be more strongly associated with the patency rate.”
Risk factors for vascular access complications
A Cox proportional hazard model demonstrated that aging, female sex, diabetes mellitus, low serum albumin, and use of an erythropoietin-stimulating agent were associated with poor primary patency after vascular access construction in this study. Of these identified risk factors, aging, diabetes mellitus, and low serum albumin may be indicative of a patient’s poor general condition, the study authors muse, while female sex has reportedly been associated with smaller vascular diameter, which can increase the number of vascular access problems. “Taken together these results indicate that vascular access patency might be improved if modifiable risk factors identified in the present study are well controlled,” Yoshida et al write.
Furthermore, aging, diabetes mellitus, polycystic kidney disease, initiation of haemodialysis with the use of a temporary catheter, and a shorter period from vascular access construction to use were associated with poor patency after the first PTA. These results led the study investigators to conclude that patients need to start haemodialysis “urgently”.
“These findings suggest that with the exception of aging and diabetes mellitus, different risk factors contribute to the incidence of vascular access problems after surgical construction of vascular access and restenosis after PTA,” the authors conclude.
“Our data showed that stenosis accounted for 92% of vascular access problems. […] These findings suggest that the presence or absence of procedure-induced stimulation may cause differences in the risk factors that influence the patency rates after vascular access construction and that after PTA.”