Figure 4
In vitro results using clinically collected patient effluent samples. (a) Confusion matrix for 94 peritoneal dialysis patient effluent samples using a 50 white blood cells (WBCs)/mm3 threshold separating “positive” for infection caution (yellow, red zones) from “negative” for infection caution (green zone). Some of the healthy baseline samples (0–10 WBCs/mm3) were spiked to a concentration of 100 WBCs/mm3 (n = 33). (b) The receiver operating characteristic (ROC) curve, evaluated by varying the binary classification threshold from 0 WBCs/mm3 to the maximum WBC concentration prediction in the dataset. The area under the ROC (AUROC) was 0.97. The red marker denotes the threshold balancing sensitivity and specificity (50 WBCs/mm3). The dotted line represents the ROC of a random classifier for comparison. (c) Predicted WBC concentrations for effluent samples with healthy baseline concentrations (n = 44) (left) and those spiked to about 100 WBCs/mm3 (n = 33) (right). Predicted concentrations were classified in the healthy zone if < 50 WBCs/mm3 (green), caution zone if between 50 WBCs/mm3 and 100 WBCs/mm3 (yellow), and in the risk zone if ≥ 100 WBCs/mm3 (red). False negatives are shown as purple markers. Error bars are s.d. (d) Predicted WBC concentrations of effluent samples with elevated baseline WBC concentrations above 10 WBCs/mm3 (n = 17) (circle markers), including three lab-confirmed peritonitis-positive samples (triangle markers). Most samples with concentration greater than 10 WBCs/mm3 are correctly classified; three false positives are shown as purple markers. (e) Comparison of predicted WBC concentrations in patient effluent collected over time from OpticLine (blue) and a lab-grade Cellometer (red). The dotted line represents the binary classification threshold of 50 WBCs/mm3. f, Predicted WBC concentrations across different sample levels for four potential confounders. High WBC concentrations were produced by spiking WBCs in patient effluent (left). Percent whole blood was added to effluent spiked to a concentration of 100 WBCs/mm3 (left, middle). Temperature (right, middle) and effluent flow rate (right) at sample measurement were also evaluated. For an actual concentration of 0 WBCs/mm3, OpticLine predicted concentrations of 0 WBCs/mm3 with no s.d. at both tested temperatures. Error bars are s.d. “n.s.” represents no statistically significant difference between the given samples.
