Table 4.
Sensitivity, specificity, positive and negative predictive values (PPV/NPV) of Connective Tissue Disease Screening Questionnaire (CSQ) responses and autoantibody testing for the identification of individuals with inflammatory arthritis (IA)(N=84) on examination during health-fair screening *
| CSQ and/or Autoantibody Testing | Sensitivity % (95% confidence interval) | Specificity % (95% confidence interval) | PPV, NPV (% and 95% confidence intervals) of testing in this screen where prevalence of IA was ~14% (95% confidence interval) * | PPV, NPV (Estimated Prevalence of IA 1%) | PPV, NPV (Estimated Prevalence of IA 5%) |
|---|---|---|---|---|---|
| CSQ only, ≥1 Positive Responses** | 91.8 (83.2–96.3) | 34.7 (30.6–39.0) | 18.8 (15.2–22.9), 96.2 (92.1–98.3) | 1.4, 99.8 | 6.9, 98.8 |
| Parallel testing: CSQ or autoantibodies positive*** | 95.3 (87.7–98.5) | 32.4 (28.4–36.6) | 18.8 (15.3–22.9), 97.7 (93.7–99.2) | 1.4, 99.9 | 6.9, 99.2 |
| Serial testing: CSQ positive, then autoantibodies positive*** | 27.1 (18.3–38.0) | 94.8 (92.4–96.5) | 46.0 (32.1–60.5), 88.7 (85.7–91.2) | 5.0, 99.2 | 21.5, 96.1 |
| CSQ only, ≥2 Positive Responses** | 78.8 (68.3–86.6) | 61.4 (57.1–65.6) | 25.2 (20.2–30.9), 94.6 (91.5–96.7) | 2.0, 99.7 | 9.7, 98.2 |
| Parallel testing: CSQ or autoantibodies positive*** | 87.1 (77.6–93.1) | 56.4 (52.0–60.7) | 24.5 (20.0–30.1), 96.4 93.4–98.1) | 2.0, 99.8 | 9.5, 98.8 |
| Serial testing: CSQ positive, then autoantibodies positive*** | 22.4 (14.3–32.9) | 97.1 (95.1–98.3) | 55.9 (38.1–72.4), 88.4 (85.4–90.8) | 7.2, 99.2 | 28.9, 96.0 |
| CSQ ≥3 Positive Responses** | 57.6 (46.5–68.1) | 74.8 (70.8–78.5) | 27.4 (21.1–34.6), 91.5 (88.3–93.9) | 2.3, 99.4 | 10.7, 97.1 |
| Parallel testing: CSQ or autoantibodies positive*** | 72.9 (62.0–81.7) | 68.4 (64.2–72.4) | 27.6 (21.9–34.0), 93.9 (90.8–96.0) | 2.3, 99.6 | 10.8, 98.0 |
| Serial testing: CSQ positive, then autoantibodies positive*** | 15.3 (8.7–25.1) | 98.4 (96.8–99.3) | 61.9 (38.7–81.0), 87.6 (84.6–90.1) | 8.8, 99.1 | 33.5, 96.0 |
| CSQ ≥4 Positive Responses** | 21.2 (13.4–31.7) | 90.3 (87.3–92.7) | 26.5 (16.8–38.8), 87.4 (84.2–90.1) | 2.2, 99.1 | 10.7, 95.6 |
| Parallel testing: CSQ or autoantibodies positive*** | 40.0 (29.7–51.2) | 83.1 (79.6–86.2) | 28.1 (20.5–37.1), 89.4 (86.2–91.9) | 2.3, 99.3 | 11.7, 96.3 |
| Serial testing: CSQ positive, then autoantibodies positive*** | 11.8 (6.1–21.0) | 99.2 (97.9–99.8) | 71.4 (42.0–90.4), 87.2 (84.2–89.8) | 13.0, 99.1 | 43.7, 95.5 |
| RF positive | 29.4 (20.2–40.4) | 94.2 (91.7–96.0) | 45.4 (32.7–59.3), 89.0 (86.0–91.4) | 4.8, 99.2 | 21.1, 96.2 |
| Anti-CCP positive | 10.6 (5.3–19.6) | 97.3 (94.2–97.5) | 39.1 (20.5–61.2), 86.9 (83.8–89.4) | 3.8, 99.1 | 17.7, 95.4 |
| RF or anti-CCP positive | 30.6 (21.3–41.7) | 92.1 (89.3–94.2) | 38.8 (27.4–51.5), 89.0 (85.9–91.4) | 3.8, 99.2 | 16.9, 96.2 |
| RF and anti-CCP positive | 9.4 (4.4–18.2) | 99.4 (98.2–99.8) | 72.7 (39.3–92.7), 86.9 (84.0–89.5) | 13.7, 99.1 | 45.2, 95.4 |
| CRP positive (≥0.8 mg/dL) | 12.9 (6.9–22.4) | 89.3 (86.2–91.3) | 16.7 (9.0–28.3), 86.1 (82.9–88.9) | 1.2, 99.0 | 6.0, 95.1 |
For this study, the presence of ≥1 swollen joint suggestive of synovitis as determined by a rheumatologist or nurse trained in joint examination is classified as inflammatory arthritis (IA).
CSQ=Connective Tissue Disease Screening Questionnaire. This is a subject-completed questionnaire which can assess self-reported fulfillment of the following ACR RA criteria (Arnett FC et al, 1988): >6 weeks of arthritis symptoms; morning stiffness ≥1 hour, hand arthritis (fingers, wrists), 3 or more joint areas (hands, wrists, elbows, and knees), and symmetric arthritis; nodules. Radiographic findings are not assessed, and for this study, self-reported results of RF testing are not included. Each positive response was determined to be self-reported fulfillment of 1 ACR criteria for RA.
Parallel testing: CSQ and autoantibodies are performed simultaneously; Serial testing: data is analyzed assuming that CSQ is performed first, and autoantibody testing is then performed only in those with ‘high-risk’ CSQ responses (which vary by cut-off evaluated: ≥1, ≥2, etc)
Abbreviations/units: PPV=positive predictive value; NPV=negative predictive value; CSQ=Connective Tissue Disease Screening Questionnaire; Anti-CCP=anti-cyclic citrullinated peptide antibodies, units per milliliter (U/mL), positive value >5 U/mL; RF=rheumatoid factor, international units per mL (IU/mL0, positive value >14 IU/mL; CRP= C-reactive protein, mg/deciliter (mg/dL), positive value ≥0.8 mg/dL; RA=rheumatoid arthritis; IA=inflammatory arthritis