Between May 1,2019, and April 30, 2020, a total of 312 critically ill patients from 4 participating hospital ICU of the Zhejiang province in China, who accepted nutritional treatment for more than 3 days, were included. Of these, 302 patients were finally enrolled (Fig. 1). As demonstrated in Fig. 1, the following patients were excluded:2 patient who were readmitted, 5 patient who received the CRRT therapy, 1 patient who withdrew consent, 1 patient who recently admitted to another hospital and 1 patient who discontinued treatment. All patients were divided into RFS and Non-RFS groups. According to the serum phosphate level, those in the RFS group were further divided into three subgroups: Group 1 (n = 18), Group 2 (n = 60), and Group 3 (n = 30) (Fig. 1).
As shown in Table 1, the enrolled patients included medical and surgical patients, and the latter included those who underwent elective surgery or emergency surgery. Central nervous system diseases and infectious diseases ranked as the top 2 primary diseases indicated for ICU admissions. Hypertension, type 2 diabetes, and cardiovascular disease were the top three chronic complications. There were no statistical differences in the distribution of these among the four subgroups.
Baseline characteristics are compared in Table 2. The mean age of the participants varied from 59 to 63 years of age. Women were accounted for 16.7–40%. At enrolment, the mean APACHE II score varied from 15.36 to 19.13 and this score was significantly higher in Group 2 (p = 0.009) and Group 3 (p = 0.01) than in the Non-RFS group.
Regarding the nutritional parameters, the mean time before starting EN treatment was between 33–43 hours and the percentage of those starting nutrition within 48 hours was 70%-83%. Except for the baseline NRS2002 and BMI index, no significant differences were found in the baseline data (Fig. 3 and Table 2). The NRS2002 score in Group 2(p < 0.001) and Group 3(p = 0.001) was higher than the Non-RFS group. Moreover, the BMI index in Group 3 was lower than the Non-RFS group (p = 0.001) (Table 2).
The electrolyte and glucose levels are shown in Fig. 2. There was a correlation at different times for electrolyte and serum phosphate levels. The levels were lower in Group 2 and Group 3 compared with the Non-RFS group. The serum potassium, magnesium, and calcium levels did not reach statistical significance in the different groups. The serum glucose level,3 days after starting nutrition, was significantly different between the groups. These levels were significantly higher in Group 2 and Group 3 compared with the Non-RFS group (Fig. 2).
In terms of organ injury, Pro-BNP and total blood bilirubin were significantly increased in the RFS group after 3 days of nutrition treatment. Of those in the RFS group, Pro-BNP was highest in Group 3. The Pro-BNP level of the RFS group was higher than that in the non-RFS group. Moreover, the total bilirubin level was significantly higher in Group 2 than in Group 1 (Figure S1). There were no significant differences in other organ changes between the different groups(Figure S1, Tables 2 and 3). As depicted in Table 3, the rate of nosocomial infection in the RFS groups (Group 2 and 3) was higher than the Non-RFS group but the difference was not statistically significant.
The median time of ICU length of stay, duration of mechanical ventilation, and the 90-day mortality had no statistical significance (Table 3). The length of hospital stay in Group 2 was significantly shorter than that in the non-RFS group. Furthermore, the 28-day mortality increased. This may be associated with the short hospital LOS, and the difference was statistically significant.
According to the preliminary results, the clinical prognosis of RFS2 was worse than that of the non-RFS group. The researchers had thought that RFS2 criteria may potentially be the best diagnostic criterion. To assess this, the enrolled participants were further divided into the modified RFS group and modified non-RFS group. We found that the nutrition risk indices such as NRS2002 score and BMI index were higher in the modified RFS group than the modified non-RFS group (p < 0.001 and p = 0.04, Table S1). The APACHE II score was also higher in the modified RFS group compared with the modified non-RFS group. However, the percent of high-risk RFS patients were not significantly different between the two modified groups (Table S1).
As shown in Table 4, the median time of ICU/hospital LOS, duration of mechanical ventilation, and the percent of AKI were not statistically significant (p > 0.05). The frequency of nosocomial infection was higher in the modified RFS group versus the modified non-RFS group, p = 0.04. Furthermore, the 28- and 90-day mortality were obviously higher in the modified RFS group, and the difference was statistically significant.