Agreement between a test for high levels of anticyclic citrullinated peptide antibody (Y) and a hypothetical true diagnosis of RA (D), given that R in Table 1 is an imperfect reference standard.
| D | |||
|---|---|---|---|
| + | – | ||
| Y | + | 289 | 10 |
| – | 43 | 13 | |
Sensitivity = 289/(289 + 43) = 0.87, specificity = 13/(13 + 10) = 0.57, positive predictive value = 289/(289 + 10) = 0.97, negative predictive value = 13/(13 + 43) = 0.23, positive DLR = sensitivity/(1-specificity) = 0.87/(1–0.57) = 2.00, and negative DLR = (1-sensitivity)/specificity = (1–0.87)/0.57 = 0.23. DLR: diagnostic likelihood ratios; RA: rheumatoid arthritis.