C4A and lobular neoplasia: The sensitivity, specificity, PPV, NPV, and OR (95% CI) for identification of patients with LN were 82.9%, 76.7%, 67.4%, 88.5%, and 11.278 (3.994–31.846) for a combination of anti-C1q and anti-dsDNA antibodies, 85.7%, 80.0%, 71.4%, 90.6%, and 16.500 (5.485–49.878) for a combination of anti-C1q antibody and levels of C3 and C4, and 80.0%, 70.0%, 76.0%, 80.4%, and 14.462 (5.157–40.553) for a combination of anti-C1q antibodies, anti-dsDNA antibodies, and levels of C3 and C4 anti-C1q Ab (Table 7).