The ALTRA Cohort
A collaboration with the University of Colorado Anschutz Medical Campus and UC San Diego Health Sciences
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Lead Collaborators:
Gary S. Firestein, UC San Diego Clinical and Translational Research Institute Project Lead
Kevin Deane, University of Colorado Anschutz Medical Campus Project Lead
To enable comparisons across the spectrum of Rheumatoid Arthritis (RA) risk, progression, and disease, the Allen Institute for Immunology–University of California, San Diego–University of Colorado Transition to Rheumatoid Arthritis (ALTRA) cohort included subjects from 3 categories of clinical presentation:
- Individuals at-risk for future clinical RA based on clinical laboratory tests (anti-CCP3 IgG ELISA, referred to as the Anti-Citrullinated Protein Antibody or ACPA).
- Healthy individuals with no medical history of severe allergy, chronic infection, chronic disease, or autoimmune disease. These subjects were also required to have low levels of anti-CCP3 (< 20 units).
- Subjects with RA within 1 year of diagnosis (early RA).
You can learn more about the ALTRA cohort recruitment process and insights about reaching clinical RA populations in:
doi:10.1002/acr2.11448
All patient recruitment and sample collection was carried out with the approval of ethical review boards at the University of Colorado Anschutz Medical Campus or the University of California, San Diego.
Interactive cohort overview
Subject metadata and major risk factors are presented in the figure below. Each line represents an individual patient measured at their first visit after recruitment into the ALTRA cohort. Click and drag your mouse on the vertical axis lines to select groups of patients based on the data to highlight those subjects. Double-click an axis to reset. For deeper exploration of our subject metadata and clinical lab results, see the Rheumatoid Arthritis Clinical Data Explorer.
Summary of baseline cohort information
| Variable | ACPA- (CON1) | ACPA+ (ARI) | ACPA+ (ERA) | P value1 |
|---|---|---|---|---|
| N Subjects | 38 | 45 | 11 | - |
| Age at sample collection, mean years (SD) | 56 (16) | 57 (16) | 49 (9) | 0.23 |
| Sex: Female, n (%) | 34 (89%) | 36 (80%) | 10 (91%) | 0.52 |
| Sex: Male, n (%) | 4 (11%) | 9 (20%) | 1 (9%) | - |
| Ethnicity: Non-Hispanic origin, n (%) | 29 (76%) | 43 (96%) | 8 (73 %) | 0.02 |
| Race: White, n (%) | 32 (84%) | 37 (82%) | 7 (64%) | 0.27 |
| BMI, mean kg/m2 (SD) | 28 (6) | 27 (5) | 30 (8) | 0.66 |
| Met ACR/EULAR 2010 criteria, n (%) | - | - | 11 (100%) | - |
| C-reactive protein, median mg/L (IQR) | 1.6 (0.6-3.4) | 1.5 (0.9-4.7) | 3.3 (1.0-10) | 0.39 |
| Erythrocyte sedimentation rate, median mm/h (IQR) | 9 (4-13) | 11 (7-20) | 20 (11-33) | 0.07 |
| Shared epitope present, n (%)2 | 13 (38%) | 18 (40%) | 6 (55%) | 0.69 |
| Serum ACPA, median (IQR) | 6 (6-6) | 62 (44-195) | 560 (230-1101) | <0.01 (<0.01 Con vs. ARI; <0.01 Con vs. ERA) |
| Serum RF IgM, median (IQR) | 5 (5-9.7) | 0.9 (0.3-23) | 69 (23-105) | 0.01 (<0.01 ARI vs. ERA; 0.06 Con vs. ERA) |
| Serum RF IgA, median (IQR) | 1.7 (1.7-1.7) | 0.3 (0.3-5.2) | 21 (1.4-35) | <0.01 (<0.01 ARI vs. ERA; 0.08 Con vs. ERA) |
1P values were calculated using the Kruskal-Wallis test for continuous variables. For P < 0.05, a Dunn’s post-hoc test with Bonferonni correction was performed and significant results are indicated in parentheses. P values were calculated using the Chi-squared test for discrete variables.
2Shared epitope present at any HLA-DRB1 *01:01, *01:02, *04:01, *04:04, *04:05, *04:08, *04:09, *04:10, *04:13, *10:00 alleles. We were unable to measure 4 CON1 participants, and these were excluded from the percent calculation.
Longitudinal summary of ACPA+ ARI who progressed to clinical RA
| Variable | Baseline Visit | IA Onset | P value1 |
|---|---|---|---|
| Age at sample collection, mean years (SD) | 51 (16) | 52 (16) | <0.01 |
| Sex: Female, n (%) | 13 (81%) | - | - |
| Ethnicity: Non-Hispanic origin, n (%) | 15 (94%) | - | - |
| Race: White, n (%) | 11 (69%) | - | - |
| BMI, mean kg/m2 (SD) | 28 (5) | 28 (5) | 0.49 |
| Met ACR/EULAR 2010 criteria, n (%) | - | 12 (75%) | - |
| C-reactive protein, median mg/L (IQR) | 2.8 (0.8-6.2) | 2.3 (1.2-3.3) | 0.98 |
| Erythrocyte sedimentation rate, median mm/h (IQR) | 12 (9-25) | 14 (8-23) | 0.71 |
| Shared epitope present, n (%)2 | 6 (38%) | - | - |
| Serum ACPA, median (IQR) | 115 (49-1581) | 171 (42-875) | 0.11 |
| Serum RF IgM, median (IQR) | 15 (0.3-34) | 15 (3.2-35) | 0.22 |
| Serum RF IgA, median (IQR) | 0.3 (0.3-5.6) | 1.7 (0.3-2.7) | 0.92 |
| Average duration in the study, days (min, max) | - | 467.9 (106-717) | - |
1P values were calculated using the paired Wilcoxon rank-sum test for continuous variables. P values were calculated using the Fisher exact test for discrete variables.
2Shared epitope present at any HLA-DRB1 *01:01, *01:02, *04:01, *04:04, *04:05, *04:08, *04:09, *04:10, *04:13, *10:00 alleles.
| Variable | Baseline Visit | IA Onset | P value1 |
|---|---|---|---|
| Age at sample collection, mean years (SD) | 46 (14) | 47 (14) | <0.01 |
| Sex: Female, n (%) | 13 (100%) | - | - |
| Ethnicity: Non-Hispanic origin, n (%) | 12 (92%) | - | - |
| Race: White, n (%) | 9 (69%) | - | - |
| BMI, mean kg/m2 (SD) | 27 (6) | 28 (6) | 0.07 |
| Met ACR/EULAR 2010 criteria, n (%) | - | 10 (77%) | - |
| C-reactive protein, median mg/L (IQR) | 3.3 (0.8-8.4) | 2.9 (1.2-4.1) | 1 |
| Erythrocyte sedimentation rate, median mm/h (IQR) | 12 (9-23) | 13 (9-21) | 0.67 |
| Shared epitope present, n (%)2 | 5 (38%) | - | - |
| Serum ACPA, median (IQR) | 133 (79-1557) | 231(51-1242) | 0.29 |
| Serum RF IgM, median (IQR) | 16 (0.3-30) | 16 (3.8-50) | 0.11 |
| Serum RF IgA, median (IQR) | 0.3 (0.3-5.2) | 1.7 (0.3-4.1) | 0.94 |
| Average duration in the study, days (min, max) | - | 497.8 (163-717) | - |
1P values were calculated using the paired Wilcoxon rank-sum test for continuous variables. P values were calculated using the Fisher exact test for discrete variables.
2Shared epitope present at any HLA-DRB1 *01:01, *01:02, *04:01, *04:04, *04:05, *04:08, *04:09, *04:10, *04:13, *10:00 alleles.