Table 2.
Metabolites contributing to the differentiation between groups, determined by analysis of PLS-DA weightings*
| Metabolite, ppm | RA patients versus controls | Patients with early arthritis before versus after resolution of inflammation | Patients with persistent arthritis versus patients with resolving arthritis (group 1) | Patients with persistent arthritis versus patients with resolving arthritis (group 2) | Patients with persistent RA versus patients with resolving arthritis (group 1) | Patients with persistent RA versus patients with resolving arthritis (group 2) |
|---|---|---|---|---|---|---|
| LDL-CH3, 0.80 | Low (6.30) | Low (3.03) | Low (6.81) | Low (2.87) | – | – |
| LDL-CH2, 1.21 | Low (7.06) | Low (31.81) | Low (7.40) | Low (6.89) | – | Low (1.58) |
| 3-hydroxybutyrate, 1.18, 1.19 | High (4.21) | High (7.90) | – | High (6.87) | – | – |
| Lactate, 1.31, 4.11 | High (54.51) | – | Low (12.85) | High (27.90) | Low (12.74) | High (16.98) |
| Alanine, 1.46, 1.48 | Low (20.00) | Low (2.15) | – | – | – | Low (3.84) |
| Acetylglycine, 2.03 | High (48.67) | High (17.41) | High (6.55) | High (6.80) | High (4.57) | Low (1.94) |
| Methylguanidine, 2.81 | Low (10.17) | – | High (92.72) | Low (38.15) | High (34.76) | Low (6.51) |
| Taurine, 3.26 | High (8.12) | High (9.11) | – | High (15.73) | – | High (8.66) |
| Glucose, 3.25, 3.88 | High (16.8) | High (12.72) | – | High (11.55) | – | High (7.49) |
| Lipid, 5.32 | Low (2.36) | Low (2.53) | – | – | – | – |
| Urea, 5.79 | – | High (1.32) | High (3.90) | – | High (1.25) | – |
*
“High” indicates that the metabolite was at a higher concentration in the rheumatoid arthritis (RA; column 2), early arthritis before resolution (column 3), persistent arthritis (columns 4 and 5), or persistent RA (columns 6 and 7) phenotypes. Nuclear magnetic resonance chemical shifts (in parts per million), which identify the location of the major peaks in the spectra, are shown for each metabolite. Values in parentheses are the variable importance of the projection for each metabolite. PLS-DA = partial least-squares discriminant analysis; LDL-CH3 = low-density lipoprotein CH3.