Characteristics and mortality of patients with and without cardio-renal syndrome treated by peritoneal dialysis in France

Abstract

Summary

Introduction
Overall, peritoneal dialysis (PD) is increasingly indicated for refractory heart failure. The aim of this study was to analyze the characteristics and survival of PD patients with and without cardiorenal syndrome (CRS) in France.

Methods
This was a retrospective study that included all patients enrolled in the French Language Peritoneal Dialysis Registry (RDPLF) between 01/01/2010 and 01/12/2021. The cohort was divided into two groups to compare patients with and without CRS. Survival was analyzed by the Kaplan-Meier method, and the log-rank test was used to compare the two groups. Factors associated with mortality in both groups were identified with Cox regression analysis.

Results
11,730 PD patients were included. Their mean age was 66.78±16.72 years. Of these patients, 766 (6.53%) were managed in PD for CRS and 10,964 for another initial kidney disease. Patients with CRS were older and had more comorbidities. Survival was significantly better in the group without CRS. The median survival times were 17.7±1.2 months and 49.6±0.7 months in patients with and without CRS, respectively. Multivariate Cox regression analysis revealed that age, male sex, diabetes, cardiovascular pathology, and lack of autonomy were factors associated with increased mortality in the group without CRS. In patients with CRS, only the variables age and history of liver disease were significantly associated with an increased risk of death. The number of peritonitis episodes with which a patient presented was significantly associated with a lower risk of death in both groups.

Conclusion
This nationwide study of a large number of patients treated with PD revealed the large differences in characteristics and survival between those with and without CRS. In particular, the two factors most related to mortality in the group with CRS were age and liver disease.

INTRODUCTION

Cardiorenal syndrome (CRS) has been defined by C. Ronco as «a complex pathophysiological entity involving the heart and kidneys in which acute or chronic dysfunction of one organ may induce acute or chronic dysfunction of the other»[1]. Associated heart failure and chronic kidney failure increase patient morbidity and mortality. Both conditions share common risk factors such as diabetes and hypertension. Chronic kidney failure worsens cardiovascular disease through hypertension and the vascular calcifications it induces. Heart failure worsens chronic kidney failure via neurohormonal mechanisms, activation of inflammation, increased central venous pressure and renal hypoperfusion. Oxidative stress and fibrosis play major roles in the pathogenesis of cardiac indufficiecy with chronic kidney failure[2].

According to Santé Publique France[3], in 2019, 2.3% of the French population had cardiac insufficiency. That rate increased to 10% for patients aged 70 years or more. In some studies, the prevalence of chronic kidney disease in patients with acute or chronic cardiac insufficiency has been estimated at 49%[4]. At that rate, 70,213 deaths would be associated with cardiac insufficiency each year in France. Mortality after diagnosis would be 20% at 1 year and 53% at 5 years for all types of cardiac insufficiency[5].

Refractory cardiac insufficiency is defined as persistence of symptoms despite maximal therapy; mortality is reported to be 25–75% at 1 year[2]. In refractory cardiac insufficiency, chronic kidney failure and resistance to diuretics are often seen. Dialysis tre]tment may be proposed to perform ultrafiltration (UF) to control sodium water overload. If end-stage kidney disease (ESKD) is present, dialysis will also be used to remove waste products. Two dialysis techniques are possible: peritoneal dialysis (PD) and hemodialysis (HD). No study has been able to prove the superiority of one or the other technique in this context[7]. PD would allow a better maintenance of residual renal function than HD. Hemodynamic tolerance would be better with PD than with HD in patients over 75 years of age[8]. PD in cardiac insufficiency would allow less neurohormonal stimulation, better preservation of residual renal function and better hydro-sodal extraction. Preservation of residual renal function in dialysis patients would be associated with better survival[9]. Another advantage of PD is that it can be performed daily at home.

There appears to be an improvement in dyspnea according to NYHA stage[10];[11];[12], and a reduction in the duration and frequency of hospitalizations for acute cardiac failure in chronic cardiac inssufficiency patients treated with PD[13];[14];[15]. This may result in an improvement in quality of life[14], but no reduction in mortality has been observed[15]. An improvement in LVEF has been noted [16). To our knowledge, cohort studies concerning patients with chronic cardiac failure managed in PD are relatively old and involve few patients[12];[15];[17];[18]. The last French cohort study, which dates from 2014[13], included 126 patients from 2 PD centers.

The French Language Peritoneal Dialysis Registry (RDPLF), launched in 1986, includes patients treated by PD in France. Our study was based on the national data from the RDPLF. It aimed to estimate the evolution of the incidence of patients with CRS managed in PD ; to describe the clinical characteristics, the therapeutic modalities and the trajectories of these patients ; and to compare them to patients without CRS. Finally, it aimed to estimate and analyze the survival of patients with and without CRS.

Materials and methods

Type of study, context and participants

This was a retrospective study including all PD patients aged 18 years and older registered in the RDPLF between 01/01/2010 and 01/12/2021 and residing in metropolitan France. Duplicates related to transfer from one structure to another and patients who did not have well-defined initial kidney disease were excluded.

The RDPLF has been comprehensive since 1995. It consists of several modules. The main module must be updated regularly when a center commits to participation. The heart failure module is an additional module, implemented in 2012, which has been voluntarily completed by a few centers.

Definitions

Patients identified as having CRS are those for whom this diagnosis was scored as initial kidney disease in the registry. The main registry module does not contain information on ejection fraction or heart disease. Automated peritoneal dialysis (APD) uses a cycler for nocturnal automated exchanges. Continuous ambulatory peritoneal dialysis (CAPD) requires several manual exchanges per day.

According to Ronco et al. [1), 5 types of CRS have been defined. These are CRS type 1: acute heart failure inducing acute kidney failure; CRS type 2: chronic heart failure inducing chronic kidney failure; CRS type 3: acute kidney failure inducing acute heart failure; CRS type 4: chronic kidney failure inducing or aggravating heart failure; and CRS type 5: combined heart and kidney failure due to acute or chronic systemic disease.

Collected variables

The following data were extracted from the main module:

Age; sex; body mass index (BMI); initial kidney disease; Charlson score at start of PD; history of myocardial infarction (MI); history of congestive heart failure; history of peripheral arterial disease; history of stroke or transient ischemic attack (TIA); history of pulmonary pathology; history of liver disease; history of diabetes; history of neoplasia; treatment prior to PD (non-dialysis, transplantation, HD); date of PD management; type of treatment performed in PD at

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