Results
Table 1 presents the baseline characteristics of the study population. There was no difference between the PE group and the control group in age, parity, the proportion of twin pregnancies, preexisting hypertension or diabetes mellitus, or the proportion of gestational hypertension or diabetes mellitus. The gestational age at hospitalization was lower in the PE group than in the control group (32.8 weeks versus 37.0 weeks of gestation, respectively). The most common sign in the PE group was high blood pressure, followed by proteinuria, presence of PE-related symptoms, and elevation of liver enzymes. Increased levels of creatinine, thrombocytopenia, and pulmonary edema were observed in less than 10% of the patients. In the control group, no signs or symptoms except for high blood pressure and proteinuria were observed.
Table 2 shows the signal intensity distribution of the aptamer-based assay according to the severity of PE. Of the 50 women with PE, 37 (74%) showed severe symptoms after admission, and 13 (26%) were diagnosed with PE without severe symptoms. Of the 52 women with signal 0 in the assay, 43 (83%) were in the control group, and 9 (17%) were diagnosed with PE (regardless of the signal 0 in the assay). On the other hand, 80% of women with signal 2 and 71% of those with signal 3, respectively, showed PE with severe features. Only 14% of women with signals 2 or 3 were in the control group. The linear-by-linear association between the signal intensity and severity of PE was shown to be significant. The quantified concentration of nephrin measured from clinical samples by ELISA and the receiver operating characteristic curve are shown in Figure 3. The area under the curve (AUC) regarding the diagnosis of PE was 0.688, and the P -value was <0.005.
Table 3 shows the diagnostic performance of the assay in PE and PE with severe features when the intensity of the assay was ≥1 and ≥2, respectively. When signal 1 (or higher) was positive, the detection rate for PE was 82% and the detection rate for PE with severe features was 89%, which was significantly higher than that of signal 2 (or higher) when positive. When signal 1 (or higher) was positive, the negative predictive value for PE with severe features was 92.3%. However, when signal 2 (or higher) was positive, the false-positive rate (1-specificity) was 6%, which was significantly lower than that of signal 1 (or higher).