Soluble urokinase plasminogen activator receptor (suPAR) predicts critical illness and kidney failure in patients admitted to the intensive care unit

Figures

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  Figure 1. Z-standardized biomarkers for prediction of ICU mortality. z-standardization = all four biomarkers standardized to a mean of zero and a standard deviation (SD) of 1. Note that the hollow green diamonds represent the odds ratio for the respective biomarker, and the associated bars represented the 95% confidence interval. The black vertical line represents an odds ratio of 1 (“line of unity”). ICU = intensive care unit; CI = confidence interval; suPAR = soluble urokinase plasminogen activator receptor; CRP = C-reactive protein; PCT = procalcitonin; IL-6 = interleukin-6.

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  Figure 2. Association of ICU mortality with suPAR quartiles. The highest compared to the lowest quartile of suPAR had an odds ratio (OR) of 4.7 for ICU mortality. In the figure, the upper border of the confidence interval was truncated at the OR of 6.

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  Figure 3. Overall survival for suPAR levels above or below a 12 ng/mL cutoff. Median follow-up of the total cohort was 2.9 months with 96 observed deaths from any cause. Using a previously published suPAR cut-off at 12 ng/mL for validation, Kaplan–Meier overall survival estimates at 3 months were 63% in the 160 patients with baseline suPAR levels below 12 ng/mL, and 49% in the 77 patients with baseline suPAR levels ≥ this cut-off (log-rank p = 0.027).

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  Figure 4. (A) Random forest analysis—overall survival according to risk stratification groups. For this analysis, we used the random forest machine learning method with the CHAID algorithm treating ICU mortality as a dependent variable and suPAR and SOFA score as independent variables, with tenfold cross validation. The random forest proposed cut-off values for SOFA score at 7 points (corrected p < 0.0001) and for suPAR at 8 ng/mL (corrected p = 0.022). Note that in patients with a SOFA score > 7 the prognosis was determined solely by the SOFA score. (B) Random forest analysis – Overall survival according to risk stratification groups. ICU mortality was 53% in patients with a SOFA score > 7 points (n = 99), 17% in patients with a SOFA score ≤ 7 points and suPAR levels > 8 ng/mL (n = 54), and 2% in patients with a SOFA score ≤ 7 points and suPAR levels ≤ 8 ng/mL (n = 84). Log-rank p < 0.0001.