Table 2.

Test characteristics for urinary low-molecular-weight protein excretion to predict progression in 129 iMN patients

Threshold Value	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	False Positives (n)	False Negatives (n)	Test Positives (n)
uβ2m
≥0.5 μg/min	80	67	68	79	23	12	71
≥1.0 μg/min	73	75	72	76	17	16	61
≥1.5 μg/min	65	83	76	73	12	21	51
≥2.0 μg/min	58	83	76	70	12	24	47
≥2.5 μg/min	55	84	75	68	11	27	44
uα1m
≥40 μg/min	77	71	70	78	20	14	66
≥50 μg/min	65	83	76	73	12	21	51
≥60 μg/min	57	86	77	69	10	26	44
≥70 μg/min	45	88	77	65	8	33	35
≥80 μg/min	42	90	78	64	11	27	44

iMN, idiopathic membranous nephropathy; PPV, positive predictive value; NPV, negative predictive value; uβ2m, urinary β2-microglobulin; uα1m, urinary α1-microglobulin. Test positives are the number of patients with a urinary α1- and β2-microglobulin excretion greater than the threshold value.