Outcomes
In pooling the included studies, the effect of AST-120 on the following primary outcomes was determined: mortality, incidence of ESRD (initiation of renal replacement therapy), and doubling of serum creatinine. The effect of AST-120 on the secondary outcomes of interest were not evaluated due to the paucity of data in the retrieved clinical trials. Likewise, the intended analyses on the prespecified subpopulations were forgone due to the lack of pertinent data in the included studies.
In terms of the outcome of all-cause mortality, four trials were pooled, with a resulting total population size of 1503 in the interventional group and 1494 in the control group. There were a total of 110 mortalities in the interventional group and 116 mortalities in the control group, yielding a risk ratio (RR) and 95% confidence interval (CI) of 0.94 [0.74, 1.21]. This finding suggests that AST-120, compared to standard treatment, has no effect on the outcome of mortality among patients with CKD. The Forest plot for this primary outcome is shown in Figure 3 .
Regarding the effect of AST-120 on the initiation of RRT, the pooled data shows that there were 353 events out of a total sample size of 1524 in the interventional group while there 374 events out of a total population of 1517 in the control group. This gives a risk ratio with 95% CI of 0.94 [0.83, 1.07] with no heterogeneity. This finding suggests that AST-120 confers no significant benefit in preventing or delaying the incidence of ESRD or initiation of RRT among adults with CKD (Figure 4) .
Lastly, in terms of the effect of AST-120 on the doubling of serum creatinine, four trials were pooled, giving a total population of 1503 in the interventional group and 1494 in the control group. There were a total of 155 incidences of doubling of serum creatinine in the AST-120 group and also 155 incidences in the control group. This yields a risk ratio with 95% CI of 0.99 [0.80, 1.22] with no heterogeneity, suggesting that AST-120 has no significant effect on the outcome of doubling of serum creatinine (Figure 5 ).
Pooled analysis on the adverse events associated with AST-120 cannot be generated from the studies included in this review due to inadequate recording and differences in reporting of adverse events. In general, usual adverse effects reported in the studies are gastrointestinal in nature.