Fig.3 Comparison of forest plot of overall mortality rate between CRRT and control groups
3.4.2 APACHEⅡscores
Twenty-one studies compared the impact of CRRT group and control group on APACHE II scores. Due to large heterogeneity (I2=91%), random effects model was used for analysis, and the results showed that the difference was statistically significant(WMD=-4.20, 95%CI-4.81 to -3.58,P<0.00001)( Fig.4). Patients treated with CRRT had lower APACHE II scores than those in the control treatment group. Because APACHE II is a score that reflects the severity of a patient’s illness, patients with a score greater than 15 are often considered as critical in ICU. Therefore, we conducted a subgroup analysis of the included studies based on the size of APACHE II after intervention, with the boundary of 15. Based on sensitivity analysis, the results of Wang Y, Yu DZ and Li Q crossed the invalid line and were obviously inconsistent with other research trends, therefore the three studies were excluded. I2 went from 91% to 76%.