Abdominal aortic calcification score as a predictor of clinical outcome in peritoneal dialysis patients: a prospective cohort study

Abstract

Background: Abdominal aortic calcification assessed by X-ray is recommended to evaluate vascular calcification in dialysis patients. It has been shown that abdominal aortic calcification score (AACS) is a predictor of adverse outcomes in hemodialysis patients, but evidence regarding its prognostic value in peritoneal dialysis (PD) patients is still insufficient. We aimed to examine the predictive role of AACS for major adverse cardiac and cerebrovascular events (MACCE) and mortality in PD patients. Methods: Eligible patients undergoing PD between July 2011 and July 2014 were recruited. AACS was quantified using lateral lumbar radiography at recruitment. Patients were prospectively followed up until death, PD cessation, or to the end of the study (August 31, 2018). Both subdistribution hazards and cause-specific hazards models were used to evaluate the association between AACS and MACCE as well as mortality. Results: 292 patients were enrolled, including 160 males (54.8%) with mean age 57.1 ± 15.2 years and median PD duration 28.4 (IQR 12.0, 57.8) months. Among them, 75 (25.7%) patients were comorbid with diabetes, and 94 (32.2%) patients had cardiovascular disease (CVD). The average AACS was 2.0 (0.0, 6.0). Patients were categorized on the tertiles of AACS (Low AACS group, AACS = 0, n = 125; Medium AACS group, AACS 1-4, n = 72; and High AACS group, AACS> 4, n = 95). AACS was associated with age (OR = 1.081, P < 0.001), PD duration (OR = 1.012, P = 0.003), CVD (OR = 1.919, P = 0.020) and diabetes (OR = 2.554, P = 0.002). During the follow-up period of 43.6 (24.6, 50.7) months, there were 65 MACCEs and 84 deaths. Significantly higher cumulative incidences of all-cause mortality (Log-rank = 35.992, P<0.001; Gray = 38.662, P < 0.001) and MACCE (Log-rank = 26.146, P<0.001; Gray = 27.810, P < 0.001) were observed in the upper AACS tertile. AACS was an independent predictor of all-cause mortality (HR = 2.438, 95% CI 1.246-4.772, P = 0.009; SHR = 2.323, 95%CI 1.229-4.389, P = 0.009) and MACCE (HR = 3.455, 95% CI 1.734-6.884, P < 0.001; SHR = 3.063, 95%CI 1.460-6.430, P = 0.003) in this study. Conclusions: AACS was associated with age, PD duration, CVD and diabetes in PD patients. AACS could predict MACCE and all-cause mortality in this population. It thus might be a safe and feasible method to identify PD patients with adverse outcomes.

Dialysis Duration and Glucose Exposure Amount Do Not Increase Mortality Risk in Peritoneal Dialysis Patients: A Population-Based Cohort Study From 2004 to 2012

“…The first error is to ignore the PD treatment during the observation period, regardless of the treatment length (12, 18-22, 25, 26). The second is to censor the PD participants when shifting to HD, and such study design excludes those mortalities occurring after the change of renal replacement therapy modality, which is highly common (20,21,25). This also causes time-to-event analysis to show that the longer PD duration was associated with death because the incident patients with PD tend to shift to HD or have renal transplants rather than die on PD.…”

“…This also causes time-to-event analysis to show that the longer PD duration was associated with death because the incident patients with PD tend to shift to HD or have renal transplants rather than die on PD. The third, and most important, error is that those studies cannot distinguish the effect on mortality of PD treatment from uremic exposure period (18)(19)(20)(21)(22)25). The longer PD duration before enrollment also means more extended exposure to uremia, which is associated with a higher mortality risk and needs further adjustment.…”

“…Although the association of PD duration and mortality has long been investigated, no consistent conclusion has been reached ( 21 , 22 , 25 ). The main reason for this is that PD duration has seldom been correctly defined.…”

“…Irrespective of including incident or prevalent patients with PD, the authors tend to make three kinds of errors in those studies. The first error is to ignore the PD treatment during the observation period, regardless of the treatment length ( 12 , 18 – 22 , 25 , 26 ). The second is to censor the PD participants when shifting to HD, and such study design excludes those mortalities occurring after the change of renal replacement therapy modality, which is highly common ( 20 , 21 , 25 ).…”

Targeting a Silent Disease: Vascular Calcification in Chronic Kidney Disease

“…Another X-ray-based score was established by Kauppila et al [30] from a retrospective study involving 617 lateral lumbar radiographs performed on patients from the Framingham heart study. The Kauppila score, representing the abdominal aorta calcification score (AACS) [49], assesses vascular calcifications via lateral abdominal X-rays and was proven to be a simple, low cost assessment of subclinical vascular disease (Table 1). More recently, it was correlated with cardiovascular event prediction in a study involving 187 peritoneal dialysis patients, and was showed to improve risk stratification beyond the Framingham risk score in another study involving 184 hemodialysis patients [50].…”