Table 2.

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

Threshold ValueSensitivity (%)Specificity (%)PPV (%)NPV (%)False Positives (n)False Negatives (n)Test Positives (n)
uβ2m
    ≥0.5 μg/min80676879231271
    ≥1.0 μg/min73757276171661
    ≥1.5 μg/min65837673122151
    ≥2.0 μg/min58837670122447
    ≥2.5 μg/min55847568112744
uα1m
    ≥40 μg/min77717078201466
    ≥50 μg/min65837673122151
    ≥60 μg/min57867769102644
    ≥70 μg/min4588776583335
    ≥80 μg/min42907864112744
  • 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.