Impact of renal-replacement therapy strategies on outcomes for patients with chronic kidney disease: a secondary analysis of the STARRT-AKI trial

Purpose To assess whether pre-existing chronic kidney disease (CKD) modified the relationship between the strategy for renal-replacement theraphy (RRT) initiation and clinical outcomes in the STARRT-AKI trial. Methods This was a secondary analysis of a multi-national randomized trial. We included patients who had documented pre-existing estimated glomerular filtration rate (eGFR) data prior to hospitalization, and we defined CKD as an eGFR <= 59 mL/min/1.73 m(2). The primary outcome was all-cause mortality at 90 days. Secondary outcomes included RRT dependence and RRT-free days at 90 days. We used logistic and linear regression and interaction testing to explore the effect of RRT initiation strategy on outcomes by CKD status. Results We studied 1121 patients who had pre-hospital measures of kidney function. Of these, 432 patients (38.5%) had CKD. The median (IQR) baseline serum creatinine was 130 (114-160) and 76 (64-90) mu mol/L for those with and without CKD, respectively. Patients with CKD were older and more likely to have cardiovascular comorbidities and diabetes mellitus. Patients with CKD had higher 90-day mortality (47% vs. 40%, p < 0.001) compared to those without CKD, though this was not significant after covariate adjustment (adjusted odds ratio [aOR], 1.05; 95% CI, 0.79-1.41). Patients with CKD were more likely to remain RRT dependent at 90 days (14% vs. 8%; aOR, 1.89; 95% CI, 1.05-3.43). CKD status did not modify the effect of RRT initiation strategy on 90-day mortality. Among patients with CKD, allocation to the accelerated strategy conferred more than threefold greater odds of RRT dependence at 90 days (aOR 3.18; 95% CI, 1.41-7.91) compared with the standard strategy, whereas RRT initiation strategy had no effect on this outcome among those without CKD (aOR 0.71; 95% CI, 0.34-1.47, p value for interaction, 0.009). Conclusion In this secondary analysis of the STARRT-AKI trial, an accelerated strategy of RRT initiation conferred a higher risk of 90-day RRT dependence among patients with pre-existing CKD; however, no effect was observed in the absence of CKD.