Fig. 2
Frequencies of SPIP, and of positive, false positive, and false negative dipstick test results according to urinary creatinine concentration. *, P < 0.05 vs. value of the 1st quintile group. This analysis was performed in 1033 urine samples from 1033 women. For women with available antenatal P/Cr test results (n = 1004), data of the P/Cr test performed on the day closest to the day of delivery were used. In women with availability of only postnatal P/Cr test results (n = 29), data of the P/Cr test performed on the day closest to the day of delivery were used. Urine specimens were grouped into quintiles according to [Cr]: 1st quintile, [Cr] = 10.0–53.9 mg/dL; 2nd quintile, [Cr] = 54.0–90.0 mg/dL; 3rd quintile, [Cr] = 90.1–133 mg/dL; 4th quintile, [Cr] = 133.1–190 mg/dL; and 5th quintile, [Cr] = 190.1–606 mg/dL. False positive rates on dipstick test for prediction of SPIP were 37.0 % (30/81), 39.4 % (43/109), 59.4 % (85/143), 76.8 % (126/164), and 75.5 % (145/192) for the 1st, 2nd, 3rd, 4th, and 5th quintile groups, respectively. False negative rates on dipstick test for prediction of SPIP were 10.7 % (14/131), 6.5 % (6/93), 3.0 % (2/67), 7.7 % (3/39), and 7.1 % (1/14) for the 1st, 2nd, 3rd, 4th, and 5th quintile groups, respectively. The dipstick test gave false positive results exclusively in all urine specimens with [Cr] > 500 mg/dL for prediction of SPIP. The median (range) [P] increased with increasing [Cr]; 5 (1.0–493), 12 (1.0–961), 17 (1.0–1103), 22 (1.0–1342), and 28 (1.0–6170) mg/dL for the 1st, 2nd, 3rd, 4th, and 5th quintile groups, respectively, while corresponding those for women with positive dipstick test results were 27 (1.0–493) (n = 81), 27 (1.0–961) (n = 109), 23 (1.0–1103) (n = 143), 23 (1.0–1342) (n = 164), and 30 (1.0–6170) (n = 192) mg/dL for the 1st, 2nd, 3rd, 4th, and 5th quintile groups, respectively. Percentage of women with [P] ≥ 30 mg/dL increased with increasing [Cr]; 19 % (40/212), 26 % (53/202), 28 % (59/210), 28 % (57/203), and 49 % (100/208) for the 1st, 2nd, 3rd, 4th, and 5th quintile groups, respectively