Table 1.
Subject characteristics at the time of lung evaluation
| Variable | Autoantibody Positive Cases (N=42) |
Autoantibody Negative Controls (N=15) |
P-value+ | Early RA* (N=12) |
P-value++ |
|---|---|---|---|---|---|
| Age, median (quartiles 25, 75) | 54 (43, 62) | 53 (41, 67) | 0.890 | 53 (40, 59) | 1.000 |
| Female | 22 (52%) | 9 (60%) | 0.765 | 8 (67%) | 0.515 |
| Non-Hispanic White | 37 (88%) | 13 (87%) | 1.000 | 10 (83%) | 0.645 |
| ≥1 ‘shared epitope’ allele# | 22 (52%) | 8 (53%) | 1.000 | 6/7 (86%) | 0.215 |
| Ever smoked | 16 (38%) | 3 (20%) | 0.339 | 5 (42%) | 1.000 |
| Pack-years, median (range) | 7 (3,19) | 1 (1, 25) | 0.387 | 20 (16, 41) | 0.823 |
| Chronic lung disease** | 8 (19%) | 1 (7%) | 0.420 | 6 (50%) | 0.057 |
| Health-care provider diagnosed: | |||||
| Pneumonia | 18 (43%) | 2 (13%) | 0.109 | 5 (42%) | 1.000 |
| Acute bronchitis | 18 (43%) | 6 (40%) | 1.000 | 1 (8%) | 0.039 |
| Joint symptoms*** | 21 (50%) | 8 (53%) | 1.000 | Not assessed | Not assessed |
| 68-Joint count | |||||
| % with ≥1 tender joint | 8 (19%) | 2 (13%) | 1.000 | Not assessed | Not assessed |
| % with inflammatory arthritis | 0 (0%) | 0 (0%) | 1.000 | ||
| Autoantibody prevalence | |||||
| Anti-CCP2orCCP3.1 | 30 (71%) | N/A | N/A | 12 (100%) | N/A |
| Any CCP and any RF isotype | 16 (38%) | 11 (92%) | |||
| 2 or more RF isotypes | 20 (48%) | 12 (100%) | |||
| RF-IgM | 18 (43%) | 11 (92%) | |||
| RF-IgG | 24 (57%) | 9 (75%) | |||
| RF-IgA | 10(24%) | 9 (75%) |
The Early RA patients all fulfilled the 1987 ACR RA Classification Criteria (Arnett FC et al, Arthritis Rheum 1988) and were rheumatoid factor and anti-cyclic citrullinated peptide-2 positive; their median onset of arthritis symptoms prior to the lung study was 9 months, and the median time since diagnosis was 5 months. Disease-modifying anti-rheumatic drug use: 10/12 prednisone; 8/12 methotrexate; 4/12 hydroxychloroquine; 2/12 non-steroidal anti-inflammatory agents only.
Methodology for shared epitope testing provided in Kolfenbach et al Arthritis Rheum 2009.
Includes self-reported health-care provider diagnosed asthma, chronic bronchitis, emphysema, diagnosed prior to lung study (or diagnosis of RA) and ascertained after study enrollment. For Early RA subjects, 3 had a prior diagnosis of asthma, and 3 had a prior diagnosis of emphysema.
Results of standardized questionnaire performed at the time of lung study ascertaining subject-reported current or prior pain, stiffness or swelling in any of 68-joints.
P-value comparing autoantibody positive cases to autoantibody negative controls.
P-value comparing autoantibody positive cases to EarlyRA.
Abbreviations: RA = rheumatoid arthritis; N/A=not applicable.