Patient characteristics and associated factors of AACS
The cohort consisted of 292 PD patients, among whom 160 (54.8%) were males. The mean age was 57.1±15.2 years, and the median PD duration was 28.4 (12.0, 57.8) months. Among them, 75 (25.7%) patients had diabetes and 94 (32.2%) had pre-existing cardiovascular disease. The demographic characteristics, ESRD etiologies, comorbidity status, and baseline laboratory parameters were summarized in Table 1. A history of cardiovascular or cerebrovascular disease before enrollment was identified in 94 (32.2%) patients, including ischemic stroke (n=30), hemorrhagic stroke (n=7), subarachnoid hemorrhage (n=1), myocardial infarction (n=7), congestive heart failure (n=49), ischemic heart disease requiring CABG (n=2), and angina (n=19). Some patients(n=4) had had multiple CVD strikes.
Abdominal artery calcification was observed in 167 (57.2%) participants according to the results of lateral lumbar X-ray film. The median AACS of the entire cohort was 2.0 (0.0, 6.0). Patients were divided into 3 groups according to 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.
Participants with high AACS were more likely to be older, with higher BMI and a longer PD duration, more prevalent in hypertension, diabetes, and CVD, with lower serum albumin and HDL, but greater hs-CRP and TG (Table 1). Multivariate linear regression revealed that older age (OR 1.081, 95% CI 1.056 - 1.107, P< 0.001), longer PD duration (OR 1.012, 95% CI 1.004 -1.019, P=0.003), presence of diabetes (OR 2.554, 95% CI 1.415 - 4.609, P=0.002) and previous CVD (OR 1.919, 95% CI 1.108- 3.325, P=0.020) were associated with high AACS (Table 2).
Association between AACS and all-cause mortality
After the median follow-up of 43.6 (24.6, 50.7) months, 84 (28.8%) patients had died, 42 (14.4%) had been switched to hemodialysis, 22 (7.5%) had received kidney transplantation, and 11 (3.8%) had transferred to other centers.
A total of 50 patients (59.52%) died because of a lethal MACCE strike, which was the leading cause of death, including 28 cases of sudden death, 7 of acute myocardial infarction, 7 of cerebral hemorrhage, 6 of cerebral infarction, and 2 of decompensated heart failure. Infection was the second mortality cause (n=23), including peritonitis in 9 patients. The other deceased died from gastrointestinal bleeding (n=5), malignancy (n=1), or unknown causes (n=5). AACS was greater in the dead than that in the survivors [5.0 (1.0, 9.0) vs. 0.0 (0.0, 4.0), P<0.001].
The estimated cumulative mortality incidences were significantly lower in patients of Low AACS group than in their counterparts of Medium and High AACS group (Log-rank=35.992, P<0.001, Fig.1a; Gray=38.662, P < 0.001, Fig.1b). The multivariate Cox regression model showed that the baseline AACS independently predicted all-cause mortality (Medium AACS group vs. Low AACS group: HR 2.028, 95% CI 1.014-4.057, P=0.046; High AACS group vs. Low AACS group: HR 2.438, 95% CI 1.246-4.772, P= 0.009) after adjusting for age, gender, BMI, hypertension, diabetes, previous CVD, PD duration, total Kt/V, serum albumin, TG, and use of calcium-based phosphate binders (Table 3). In the presence of competing events including switch to HD, receiving kidney transplant and transfer to other centers, severe abdominal artery calcification remained independently predictable of all-cause mortality (Medium AACS group vs. Low AACS group: SHR 1.772, 95% CI 0.899-3.496, P=0.099; High AACS group vs. Low AACS group: SHR 2.323, 95%CI 1.229-4.389, P=0.009; Table 4).
The association between AACS and MACCE
MACCE occurred in 65 (22.3%) patients during the follow-up, including ACS (n=14), acute left ventricular failure (n=3), cerebral infarction (n=14), cerebral hemorrhage (n=10), and sudden cardiac deaths (n=24). Patients who developed MACCE showed higher AACS than the others did [4.5 (1.0, 8.0) vs. 1.0 (0.0, 5.0), p < 0.001].
Patients of the Low AACS group had significantly lower cumulative incidences of MACCE (Log-rank=26.146, P < 0.001; Fig.2a; Gray=27.810, P < 0.001, Fig.2b). After adjusting for age, gender, BMI, hypertension, diabetes, previous CVD, PD duration, total Kt/V, serum albumin, and LDL-c, multivariate Cox regression analysis presented the baseline AACS as an independent predictor of MACCE (Medium AACS group vs. Low AACS group: HR 2.976, 95% CI 1.420-6.238, P =0.004; High AACS group vs. Low AACS group: HR 3.455, 95% CI 1.734-6.881, P <0.001; Table 5). Further adjusted by competing events including switch to HD, receiving kidney transplant, transfer to other centers and death unrelated to MACCE, AACS remained as an independent predictor of MACCE (Medium AACS group vs. Low AACS group: SHR 2.823, 95% CI 1.333-5.970, P=0.007; High AACS group vs. Low AACS group: SHR 3.063, 95%CI 1.460-6.430, P=0.003; Table 6).