Table 1

Characteristics of patients who were ANA positive in all assays and patients who showed discordance between assays

ANA positive all assaysDisagreement among assaysP value
Age (years)*34.2 (20.2–67)38.4 (21.6–62.5)NS†
Duration of SLE (years)*6.3 (0.1–33.4)5.7 (1.6–19.8)NS
Male (%)6.3% male11.4% maleNS‡
Caucasian (%)56%66%NS‡
African American (%)38%31%NS‡
Lupus nephritis (%)67%51%NS‡
Ever anti-dsDNA positive59%23%0.0006‡
C3§ (SD)99 (32)121 (34)0.0058¶
  • *Median (range).

  • †Mann-Whitney test.

  • ‡Fisher’s exact test.

  • §Complement component C3, measured in a serum sample taken at the same time the sample for ANA was obtained.

  • ¶Unpaired t test.

  • ANA, antinuclear antibody; ds-DNA, double-stranded DNA; SLE, systemic lupus erythematosus.