Original Paper Received: April 22, 2013 Accepted: September 17, 2013 Published online: October 15, 2013
Nephron Clin Pract 2013;124:47–53 DOI: 10.1159/000355694
Type of Vascular Access and Survival among Very Elderly Hemodialysis Patients Manuel Praga a José Ignacio Merello b Ines Palomares b Inga Bayh e Daniele Marcelli e Pedro Aljama d José Luño c
a
Nephrology Division, Instituto de Investigación Hospital 12 de Octubre, Department of Medicine, Universidad Complutense, b Fresenius Medical Care, NephroCare Medical Management, c Nephrology Department, Hospital Universitario Gregorio Marañón, Madrid, and d Nephrology Department, Hospital Universitario Reina Sofía, Córdoba, Spain; e EMEALA Medical Board, Fresenius Medical Care, Bad Homburg, Germany
Key Words Central venous catheter · Hemodialysis · Vascular access · Very elderly HD patients
Abstract The use of central venous catheters (CVC) for hemodialysis (HD) is associated with higher mortality compared to arteriovenous access (AV). However, studies analyzing the influence of the type of vascular access on the survival of very elderly patients (≥75 years) initiating HD are few and involve only a limited number of patients. We studied a cohort of 5,466 incident patients who started HD; of these, 1,841 were aged ≥75. Types of vascular access for HD were classified as either CVC, which included both tunneled and non-tunneled catheters, or AV, which included AV fistula and grafts. The outcome of the study was all-cause mortality during the follow-up period. In the whole cohort, AV use was associated with a survival advantage over CVC use (88 and 63% at 2 and 5 years, respectively, in patients with an AV as compared to 75 and 48% in patients with a CVC) (p < 0.0001). Among patients ≥75, CVC use was associated with a higher number of deaths compared to AV use. Patients ≥75 with an AV showed a greater survival as compared to patients ≥75 with a CVC (80 and 53% at 2 and 5 years, respectively, vs. 68 and 43%; p < 0.0001). Multivariate analysis revealed that CVC use and the presence of arrhythmia were independent risk factors of
© 2013 S. Karger AG, Basel 1660–2110/13/1242–0047$38.00/0 E-Mail [email protected] www.karger.com/nec
death in patients ≥75, whereas obesity was associated with greater survival. In conclusion, the type of vascular access has a significant influence on the survival of very elderly patients (≥75) initiating HD. CVC use was associated with poorer survival compared to AV access. © 2013 S. Karger AG, Basel
Introduction
Different studies have demonstrated that the type of vascular access for hemodialysis (HD) has a determining influence on the survival of patients [1]. Use of an autologous arteriovenous fistula (AVF), in addition to being linked with a lower number of complications and hospital admissions, is associated with better survival compared with the use of a central venous catheter (CVC) [2–13]. HD with prosthetic arteriovenous grafts (AVG) takes an intermediate position between AVF and CVC in terms of complications and mortality [10, 12, 14]. Based on these observations, recognized guidelines strongly recommend the realization of an AVF or, if not possible, that of an AVG already in predialysis patients [15, 16]. However, no conclusive evidence is available concerning the validity of these recommendations for older patients starting HD (≥75 years). The overall survival of elderly patients is considerably lower, and the number of Manuel Praga Servicio de Nefrologia Hospital 12 de Octubre, Avda Córdoba s/n ES–28041 Madrid (Spain) E-Mail mpragat @ senefro.org
Patients The study population in this retrospective multi-center cohort study comprised incident patients on HD treatment from 63 FMC centers in Spain who started dialysis between January 1, 2007 and December 31, 2011. Inclusion criteria were age ≥18 years, ESRD vintage of less than 6 months and undergoing HD treatment for more than 3 consecutive months. The cohort of 5,466 patients was split into four different age groups: 18–44, 45–64, 65–74, and ≥75 years. The latter group (very elderly patients), comprising 1,841 patients, was compared with the whole group of patients in order to evaluate the primary outcome. In order to avoid that patients are censored when transferred to the reference hospitals in a very critical condition, all transferred patients were observed for a prolonged period of 3 months after the censoring event. The status from patients who died within this period was changed from censored to death.
For the present study, the following demographic data were recorded: age, gender, weight, height and BMI. The presence of diabetes at baseline was recorded as well as the type of HD treatment: high-flux HD or hemodiafiltration (HDF). The presence of the following comorbidities at baseline was recorded for every patient: coronary heart disease (CHD), heart failure (HF), arrhythmia, stroke, peripheral vascular disease (PVD) and malignancy. Baseline was established at 3 months after admission to an FMC center. The rationale for this baseline definition was grounded on the following considerations: (a) HD is started in a considerable proportion of patients by means of a temporary catheter while waiting for a targeted vascular access; (b) during the first 3 months on HD, outcomes can be influenced by the patient’s health status before HD commencement rather than by the type of vascular access; (c) a significant number of patients switch to another type of renal replacement therapy (peritoneal dialysis, renal transplantation) or recover sufficient renal function to discontinue HD during this period. Types of vascular access for HD at baseline were divided into two different groups: the CVC group, which included both tunneled and non-tunneled catheters, and the AV group, which included AVF and AVG. The cumulative time exposed to a particular vascular access and mean number of vascular accesses per patient-year (overall duration of all vascular accesses by patient time in years) were measured in the two groups. Also, baseline vascular access was represented as percentage of occurrence according to age, gender, treatment modality and comorbidities. Renal diagnosis, comorbidities and cause of death were recorded using the International Classification of Diseases 10 (ICD-10) [28]. Renal diagnoses were grouped into six different diagnoses: diabetes mellitus, hypertension, glomerular diseases, polycystic kidney disease, tubulointerstitial diseases and other. The crude hospitalization rate, time for first hospitalization and crude hospitalization rate due to infectious complications were also recorded in patients ≥75. High-flux HD and on-line HDF were performed with high-flux polysulfone filters with sizes ranging from 1.4 to 1.8 m2. Prescribed treatment time was around 720 min/week. Blood and dialysate flows were in excess of 300 and 500 ml/min, respectively, and substitution fluid volume in post-dilution HDF mode was >18 liters per treatment. Water purity standards were conform with stipulations for conducting high-flux dialysis and on-line HDF and the reverse osmosis water was controlled daily for composition and conductivity and monthly for bacterial growth and endotoxins. Both systolic and diastolic blood pressure (BP) were recorded at the onset and at the end of every HD session using validated electronic BP monitors. The mean ESRD vintage was 17 ± 30 days. ESRD vintage was defined as the time elapsed between the start of replacement therapy and patient admission to a NephroCare clinic. The follow-up of the whole group of patients was 710 ± 463 days. Follow-up was defined as the period of time from baseline to the end of the observation period or withdrawal from the study due to death or censoring (transfer to another dialysis center, transplantation, or end of follow-up for other reasons).
Demographic and Clinical Data Data were obtained from the FMC clinical database EuCliD®, as previously described [25–27]. All patients signed informed consent for data evaluation at their entry into the FMC centers.
Outcome Study outcome was all-cause mortality during the follow-up period. Causes of death were divided into five different groups: cardiovascular, infectious, malignancies, other, and unknown.
comorbidities is very high compared to their younger counterparts. Furthermore, several studies have shown that the adequate performance and maturation of a patent AVF for HD is more difficult to achieve in elderly patients owing to the limitations and rigidity of their compromised vascular network [17–19]. Based on these deliberations, some authors have suggested that the development of an AVF policy for elderly predialysis patients might be considered wishful thinking rather than a viable proposition [20–22]. Since the group of patients over 75 years is growing faster than others among incident HD patients in many countries [23, 24], it is fundamental to determine which type of vascular access is preferable in very elderly patients starting dialysis. To date, available information on the influence of vascular access type on mortality and complications in elderly incident HD patients is limited and inconclusive. Some studies reported increased mortality in elderly subjects (defined as >65 years) treated via a CVC versus an AVF [10, 11, 13], while no differences were found in other studies [12]. Publications including very old patients (≥75 years) are scarce and include only a very small number of patients [13]. The aim of this study was to evaluate the influence of first vascular access type (AVF and AVG vs. CVC) 3 months after admission on the mortality risk in a group of patients ≥75 years of age (n = 1,841) from a cohort of 5,466 incident patients who started HD in 63 Fresenius Medical Care (FMC) Spanish centers. Materials and Methods
48
Nephron Clin Pract 2013;124:47–53 DOI: 10.1159/000355694
Praga/Merello/Palomares/Bayh/Marcelli/ Aljama/Luño
Table 1. Baseline characteristics (n = 5,466)
Table 2. Baseline characteristics of patients ≥75 (n = 1,841)
Baseline characteristic
Age (mean ± SD) Males, % HDF, % Diabetes, % CHD, % HF, % Arrhythmia, % Stroke, % PVD, % Malignancy, %
Baseline characteristic
AV (61%)
CVC (39%)
p value
64.2±15.0 68.2 24.4 30.4 13.5 4.5 10.4 7.8 10.6 24.9
67±14.6 58.7 16.1 37.1 16.0 8.0 13.0 9.2 12.8 27.6
Nephron Clin Pract 2013;124:47–53 DOI: 10.1159/000355694
Type of Vascular Access and Survival among Very Elderly Hemodialysis Patients Manuel Praga a José Ignacio Merello b Ines Palomares b Inga Bayh e Daniele Marcelli e Pedro Aljama d José Luño c
a
Nephrology Division, Instituto de Investigación Hospital 12 de Octubre, Department of Medicine, Universidad Complutense, b Fresenius Medical Care, NephroCare Medical Management, c Nephrology Department, Hospital Universitario Gregorio Marañón, Madrid, and d Nephrology Department, Hospital Universitario Reina Sofía, Córdoba, Spain; e EMEALA Medical Board, Fresenius Medical Care, Bad Homburg, Germany
Key Words Central venous catheter · Hemodialysis · Vascular access · Very elderly HD patients
Abstract The use of central venous catheters (CVC) for hemodialysis (HD) is associated with higher mortality compared to arteriovenous access (AV). However, studies analyzing the influence of the type of vascular access on the survival of very elderly patients (≥75 years) initiating HD are few and involve only a limited number of patients. We studied a cohort of 5,466 incident patients who started HD; of these, 1,841 were aged ≥75. Types of vascular access for HD were classified as either CVC, which included both tunneled and non-tunneled catheters, or AV, which included AV fistula and grafts. The outcome of the study was all-cause mortality during the follow-up period. In the whole cohort, AV use was associated with a survival advantage over CVC use (88 and 63% at 2 and 5 years, respectively, in patients with an AV as compared to 75 and 48% in patients with a CVC) (p < 0.0001). Among patients ≥75, CVC use was associated with a higher number of deaths compared to AV use. Patients ≥75 with an AV showed a greater survival as compared to patients ≥75 with a CVC (80 and 53% at 2 and 5 years, respectively, vs. 68 and 43%; p < 0.0001). Multivariate analysis revealed that CVC use and the presence of arrhythmia were independent risk factors of
© 2013 S. Karger AG, Basel 1660–2110/13/1242–0047$38.00/0 E-Mail [email protected] www.karger.com/nec
death in patients ≥75, whereas obesity was associated with greater survival. In conclusion, the type of vascular access has a significant influence on the survival of very elderly patients (≥75) initiating HD. CVC use was associated with poorer survival compared to AV access. © 2013 S. Karger AG, Basel
Introduction
Different studies have demonstrated that the type of vascular access for hemodialysis (HD) has a determining influence on the survival of patients [1]. Use of an autologous arteriovenous fistula (AVF), in addition to being linked with a lower number of complications and hospital admissions, is associated with better survival compared with the use of a central venous catheter (CVC) [2–13]. HD with prosthetic arteriovenous grafts (AVG) takes an intermediate position between AVF and CVC in terms of complications and mortality [10, 12, 14]. Based on these observations, recognized guidelines strongly recommend the realization of an AVF or, if not possible, that of an AVG already in predialysis patients [15, 16]. However, no conclusive evidence is available concerning the validity of these recommendations for older patients starting HD (≥75 years). The overall survival of elderly patients is considerably lower, and the number of Manuel Praga Servicio de Nefrologia Hospital 12 de Octubre, Avda Córdoba s/n ES–28041 Madrid (Spain) E-Mail mpragat @ senefro.org
Patients The study population in this retrospective multi-center cohort study comprised incident patients on HD treatment from 63 FMC centers in Spain who started dialysis between January 1, 2007 and December 31, 2011. Inclusion criteria were age ≥18 years, ESRD vintage of less than 6 months and undergoing HD treatment for more than 3 consecutive months. The cohort of 5,466 patients was split into four different age groups: 18–44, 45–64, 65–74, and ≥75 years. The latter group (very elderly patients), comprising 1,841 patients, was compared with the whole group of patients in order to evaluate the primary outcome. In order to avoid that patients are censored when transferred to the reference hospitals in a very critical condition, all transferred patients were observed for a prolonged period of 3 months after the censoring event. The status from patients who died within this period was changed from censored to death.
For the present study, the following demographic data were recorded: age, gender, weight, height and BMI. The presence of diabetes at baseline was recorded as well as the type of HD treatment: high-flux HD or hemodiafiltration (HDF). The presence of the following comorbidities at baseline was recorded for every patient: coronary heart disease (CHD), heart failure (HF), arrhythmia, stroke, peripheral vascular disease (PVD) and malignancy. Baseline was established at 3 months after admission to an FMC center. The rationale for this baseline definition was grounded on the following considerations: (a) HD is started in a considerable proportion of patients by means of a temporary catheter while waiting for a targeted vascular access; (b) during the first 3 months on HD, outcomes can be influenced by the patient’s health status before HD commencement rather than by the type of vascular access; (c) a significant number of patients switch to another type of renal replacement therapy (peritoneal dialysis, renal transplantation) or recover sufficient renal function to discontinue HD during this period. Types of vascular access for HD at baseline were divided into two different groups: the CVC group, which included both tunneled and non-tunneled catheters, and the AV group, which included AVF and AVG. The cumulative time exposed to a particular vascular access and mean number of vascular accesses per patient-year (overall duration of all vascular accesses by patient time in years) were measured in the two groups. Also, baseline vascular access was represented as percentage of occurrence according to age, gender, treatment modality and comorbidities. Renal diagnosis, comorbidities and cause of death were recorded using the International Classification of Diseases 10 (ICD-10) [28]. Renal diagnoses were grouped into six different diagnoses: diabetes mellitus, hypertension, glomerular diseases, polycystic kidney disease, tubulointerstitial diseases and other. The crude hospitalization rate, time for first hospitalization and crude hospitalization rate due to infectious complications were also recorded in patients ≥75. High-flux HD and on-line HDF were performed with high-flux polysulfone filters with sizes ranging from 1.4 to 1.8 m2. Prescribed treatment time was around 720 min/week. Blood and dialysate flows were in excess of 300 and 500 ml/min, respectively, and substitution fluid volume in post-dilution HDF mode was >18 liters per treatment. Water purity standards were conform with stipulations for conducting high-flux dialysis and on-line HDF and the reverse osmosis water was controlled daily for composition and conductivity and monthly for bacterial growth and endotoxins. Both systolic and diastolic blood pressure (BP) were recorded at the onset and at the end of every HD session using validated electronic BP monitors. The mean ESRD vintage was 17 ± 30 days. ESRD vintage was defined as the time elapsed between the start of replacement therapy and patient admission to a NephroCare clinic. The follow-up of the whole group of patients was 710 ± 463 days. Follow-up was defined as the period of time from baseline to the end of the observation period or withdrawal from the study due to death or censoring (transfer to another dialysis center, transplantation, or end of follow-up for other reasons).
Demographic and Clinical Data Data were obtained from the FMC clinical database EuCliD®, as previously described [25–27]. All patients signed informed consent for data evaluation at their entry into the FMC centers.
Outcome Study outcome was all-cause mortality during the follow-up period. Causes of death were divided into five different groups: cardiovascular, infectious, malignancies, other, and unknown.
comorbidities is very high compared to their younger counterparts. Furthermore, several studies have shown that the adequate performance and maturation of a patent AVF for HD is more difficult to achieve in elderly patients owing to the limitations and rigidity of their compromised vascular network [17–19]. Based on these deliberations, some authors have suggested that the development of an AVF policy for elderly predialysis patients might be considered wishful thinking rather than a viable proposition [20–22]. Since the group of patients over 75 years is growing faster than others among incident HD patients in many countries [23, 24], it is fundamental to determine which type of vascular access is preferable in very elderly patients starting dialysis. To date, available information on the influence of vascular access type on mortality and complications in elderly incident HD patients is limited and inconclusive. Some studies reported increased mortality in elderly subjects (defined as >65 years) treated via a CVC versus an AVF [10, 11, 13], while no differences were found in other studies [12]. Publications including very old patients (≥75 years) are scarce and include only a very small number of patients [13]. The aim of this study was to evaluate the influence of first vascular access type (AVF and AVG vs. CVC) 3 months after admission on the mortality risk in a group of patients ≥75 years of age (n = 1,841) from a cohort of 5,466 incident patients who started HD in 63 Fresenius Medical Care (FMC) Spanish centers. Materials and Methods
48
Nephron Clin Pract 2013;124:47–53 DOI: 10.1159/000355694
Praga/Merello/Palomares/Bayh/Marcelli/ Aljama/Luño
Table 1. Baseline characteristics (n = 5,466)
Table 2. Baseline characteristics of patients ≥75 (n = 1,841)
Baseline characteristic
Age (mean ± SD) Males, % HDF, % Diabetes, % CHD, % HF, % Arrhythmia, % Stroke, % PVD, % Malignancy, %
Baseline characteristic
AV (61%)
CVC (39%)
p value
64.2±15.0 68.2 24.4 30.4 13.5 4.5 10.4 7.8 10.6 24.9
67±14.6 58.7 16.1 37.1 16.0 8.0 13.0 9.2 12.8 27.6
