Among the 224 patients meeting the inclusion criteria, 15 were excluded because of discharge in advance, and 3 due to unqualified records in fluid balance chart. The 206 patients who were finally included were divided into △ePVS(+) group (106 cases, 51.5%) and △ePVS(-) group (100 cases, 48.5%) according to the change of PV. Meanwhile, they were also divided into △CCS(+) group (120 cases, 58.3%) and △CCS(-) group (86 cases, 41.7%) according to the aggravation or alleviation of congestion signs and symptoms. The general information and clinical characteristics of patients was presented in Table 1. Volume status of patients in group △ePVS(-/+) and △CCS(-/+) were compared separately (Table 1).
The volume of CFB, average daily volume and number/proportion of patients at 1 to 7 days were shown in Table 2. There were no statistical difference in the CFB between △ePVS(-/+) groups during the first 3 days. The CFB in △ePVS(+) group was higher than that in △ePVS(-) group at 4 to 7 days, and there was between-group statistical significance (Figure 1A). There was no statistical difference in the CFB between the △CCS(-/+) groups during the first 3 days. CFB in the △CCS(+) group was higher than that in △CCS(-) group at 4 to 7 days, and there was between-group statistical significance (Figure 1B).
Univariate logistic regression analysis was conducted using fluid balance at 1 to 7 days as an independent variable to predict the expansion of PV (△ePVS(+)). The results showed that CFB was a risk factor for △ePVS(+) at 4 days (OR = 1.165, 95%CI = 1.064-1.275, P = 0.001), at 5 days (OR = 1.194, 95%CI = 1.1-1.295, P<0.001), at 6 days (OR = 1.075, 95%CI = 1.016-1.137, P<0.001), and at 7 days(OR = 1.164, 95%CI = 1.093-1.239, P<0.001). After adjusting for the course of HF, pulmonary rales on admission, peripheral edema on admission and 7 days after admission, orthopnea on admission, LVEF, eGFR, NT-proBNP, the multivariate logistic regression indicated that CFB was an independent risk factor for △ePVS(+) at 4 days (aOR = 1.135, 95%CI = 1.025-1.257, P<0.015), at 5 days (aOR = 1.129, 95%CI = 1.034-1.232, P = 0.007 ), and at 7 days (aOR = 1.103, 95%CI = 1.032-1.179, P = 0.004) (Table 3).
According to ROC analysis of predicting △ePVS(-/+), the AUC of CFB at 4 to 7 days were 0.672 (0.599-0.746, P<0.001), 0.722 (0.652-0.792, P<0.001), 0.644 (0.566-0.721, P < 0.001), and 0.754 (0.687-0.822, P < 0.001). The maximum Youden index was considered as a cut-off value according to ROC Analysis[20]. The cut-off values of CFB were 2.308L, 3.361L, 3.625L, and 3.816L at 4 to 7 days, and the corresponding average daily volume was 0.577L, 0.672L, 0.604L, and 0.545L (Table 4, Figure 2A).
Univariate logistic regression analysis was conducted using CFB at 1 to 7 days as an independent variable to predict the aggravation of congestion signs and symptoms (△CCS(+)). The results showed that CFB was a risk factor for △CCS(+) at 4 days (OR = 1.121, 95%CI = 1.031-1.219, P = 0.007), at 5 days (OR = 1.161, 95%CI = 1.076-1.253, P<0.001), at 6 days (OR = 1.089, 95%CI = 1.029-1.154, P = 0.004), and at 7 days (OR = 1.13, 95%CI = 1.067-1.196, P<0.001). After adjusting for educational level, course of HF, LVEF, and △ePVS, the multivariate logistic regression indicated that CFB was an independent risk factor for △CCS(+) at 4 days (aOR = 1.109, 95%CI = 1.027-1.196, P = 0.008), at 6 days (aOR = 1.062, 95%CI = 1.001-1.126, P = 0.045), and at 7 days (aOR = 1.084, 95%CI = 1.023-1.149, P = 0.007) (Table 3).
According to ROC analysis of predicting △CCS (-/+), the AUC of CFB at 4 to 7 days were 0.625 (0.547-0.702, P<0.001), 0.696 (0.625-0.768, P<0.001), 0.656 (0.581-0.73, P < 0.001), and 0.709 (0.639-0.779, P < 0.001). The cut-off values of CFB were 2.308L, 3.383L, 4.670L, and 4.622L at 4 to 7 days, and the corresponding average daily volume were 0.577L, 0.677L, 0.778L, and 0.660L (Table 4, Figure 2B).