We collected data on the given RRT treatment daily during the first five days and, thereafter, twice a week. We recorded the RRT replacement fluid flow and dilution mode, dialysis fluid flow, and the blood flow once daily. We calculated the CRRT dose (mL/kg/hr) according to previous equations [22] and considered selleck chem Imatinib treatment modality, blood flow, dilution mode, hematocrit, replacement and dialysis fluid flow, and the patient’s weight. We recorded hospital mortality, length of ICU and hospital stay, and patients’ need for RRT at 90 days from admission. We obtained patients’ vital status 90 days from ICU admission from the Finnish Population Register Centre.

DefinitionsWe calculated the total cumulative fluid balance from ICU admission to RRT initiation (including the day of RRT initiation) and defined the percentage of fluid accumulation by dividing the cumulative balance in liters by patient’s baseline weight and multiplying by 100%. We then used the cutoff value of 10% of fluid accumulation as a definition of fluid overload [18,23]. We assessed presence of sepsis on admission and on days one to five according to the American College of Chest Physicians/Society of Critical Care Medicine definition [24]. We defined renal recovery as RRT independency at 90 days from ICU admission [25].Statistical methodsWe report data as count and percentages or medians with interquartile range (IQR, 25th to 75th percentiles). We used Fisher’s exact test to compare proportions and Mann-Whitney U-test to compare continuous data and calculated 95% confidence intervals (CI) for the main outcome.

We studied factors associated with 90-day mortality with backwards logistic regression. We used stepwise elimination approach and a significance level of < 0.05 for entry and > 0.10 for removal. We entered the following variables: age, SAPS II score without age points, non-renal SOFA score on the day of RRT initiation, time from ICU admission to RRT initiation (days), initial RRT modality (continuous or intermittent), lactate (mmol/L), base excess (mmol/L), and plasma creatinine (umol/L) at RRT initiation, cumulative urine output on the day of RRT initiation, colloid use prior to RRT initiation (including data from ICU stay and 48 hours prior to ICU admission), presence of severe sepsis (yes/no) during the ICU admission, and fluid accumulation (%) at RRT initiation.

We studied fluid overload (fluid accumulation > 10%) as a categorical variable in a separate model with all other covariates being the same as in the first model. We studied the potential interactions in separate models between degree of fluid accumulation (%) and 1) SAPS II score without age points, 2) day Batimastat of RRT initiation, and 3) presence of severe sepsis 4) creatinine prior to RRT initiation and 5) urine output on the day of RRT initiation. We tested the goodness-of-fit with the Hosmer-Lemeshow test and calculated the area under the receiver operating characteristic curve (AUC) and correct classification rate.