Table 3

Positive and negative LR in SLE versus FM by ANA status

Positive LRNegative LR
ANA−ANA+AllANA−ANA+All
Low C3/C43.3 (0.2 to 50.2)>10.7 (0.9 to 128)17.0 (2.3 to 125)0.95 (0.83 to 1.1)0.73 (0.63 to 0.85)0.78 (0.69 to 0.89)
High CB-CAPs3.3 (0.5 to 21.7)12.7 (1.8 to 88)10.8 (3.4 to 33.7)0.90 (0.73 to 1.1)0.51 (0.39 to 0.67)0.59 (0.48 to 0.73)
Anti-dsDNA confirmed by IIF2.7 (0.2 to 35)> 8.0 (0.7 to 97)>6.9 (1.6 to 31.0)0.93 (0.82 to 1.1)0.80 (0.70 to 0.91)0.83 (0.75 to 0.92)
CB-CAPs in MAAA>5.7 (0.7 to 50)>29.0 (2.4 to 355)>24.0 (5.7 to 102)0.86 (0.69 to 1.1)0.27 (0.18 to 0.43)0.40 (0.30 to 0.54)
  • ANA was determined using IIF and the cut-off for a positive test result was set at ≥1:40. Positive LR is calculated as sensitivity/(1- specificity). Negative LR is calculated as 1- sensitivity/(specificity). CIs (95%) are provided.

  • ANA, antinuclear antibodies; CB-CAP, cell bound complement activation product; dsDNA, double-stranded DNA; IIF, indirect immunofluorescence; LR, likelihood ratio; FM, fibromyalgia; MAAA, multi-analyte assay with algorithm; NA, not applicable: none of the patients ANA negative were anti-dsDNA-positive; SLE, systemic lupus erythematosus.