Table 3.
Baseline characteristics of subjects by those with and without incident clinically significant dyspnea on exertion
| Study sample of primary analysis (MRC score < 3 at baseline) (n = 829) | Prevalent clinically significant dyspnea on exertion (MRC score ≥ 3 at baseline) (n = 162) | P value | |
|---|---|---|---|
| Sociodemographics | |||
| Mean age, y (SD) | 55.7 (13.6) | 60.4 (13.0) | <0.001 |
| Female, n (%) | 683 (82.4) | 135 (83.3) | 0.77 |
| White race, n (%) | 773 (93.2) | 143 (89.9) | 0.14 |
| College degree, n (%) | 498 (60.1) | 55 (36.4) | <0.001 |
| Lifestyle and clinical | |||
| Body mass index category, n (%) | <0.001 | ||
| Underweight | 10 (1.2) | 2 (1.2) | |
| Normal | 360 (43.4) | 40 (24.7) | |
| Overweight | 263 (31.7) | 44 (27.2) | |
| Obesity | 196 (23.6) | 64 (39.5) | |
| Smoking status, n (%) | <0.001 | ||
| Never | 446 (53.8) | 47 (34.1) | |
| Past | 327 (39.5) | 75 (54.3) | |
| Current | 56 (6.8) | 16 (11.6) | |
| Mean MET‐hours/week (SD) | 5.5 (5.7) | 2.9 (3.2) | <0.001 |
| Pulmonary morbidities, n (%) | |||
| Asthma | 123 (14.8) | 41 (25.5) | <0.001 |
| Bronchitis | 250 (30.2) | 77 (47.8) | <0.001 |
| Emphysema | 13 (1.6) | 13 (8.1) | <0.001 |
| Pneumonia | 177 (21.4) | 62 (44.3) | <0.001 |
| Interstitial lung disease | 2 (0.2) | 0 (0.0) | 0.53 |
| Any of the above | 370 (44.6) | 42 (25.9) | 0.003 |
| Mean multimorbidity index count (SD)a | 0.6 (1.2) | 2.6 (1.5) | <0.001 |
| Multimorbidity index counta, n (%) | <0.001 | ||
| 0 | 567 (68.4) | 0 (0.0) | |
| 1 | 129 (15.6) | 42 (25.9) | |
| >1 | 133 (16.0) | 120 (74.1) | |
| Cough | 194 (23.4) | 45 (27.8) | 0.01 |
| Anxiety (vs none) | 316 (38.1) | 176 (54.3) | <0.001 |
| RA characteristics | |||
| Median RA duration, y (IQR) | 8 (3‐20) | 11 (4‐24) | <0.001 |
| Mean DAS28‐CRP3 score (SD) | 3.6 (1.6) | 4.2 (1.6) | <0.001 |
| Moderate/high disease activity, n (%) | 435 (52.5) | 111 (68.5) | <0.001 |
| Seropositive, n (%) | 547 (66.0) | 103 (63.6) | 0.56 |
| Mean MDHAQ score (SD) | 0.53 (0.47) | 1.10 (0.60) | <0.001 |
| Methotrexate use, n (%) | 433 (52.2) | 118 (72.8) | <0.001 |
| Non‐biologic DMARD use, n (%) | 608 (73.3) | 149 (92.0) | <0.001 |
| Biologic DMARD use, n (%) | 339 (40.9) | 86 (53.1) | 0.004 |
| Glucocorticoid use, n (%) | 230 (27.7) | 144 (88.9) | <0.001 |
| Erosion/radiographic changes present, n (%) | 418 (50.4) | 86 (53.1) | 0.54 |
| Rheumatoid nodule present, n (%) | 218 (26.3) | 53 (32.7) | 0.09 |
a
Excluding asthma and chronic obstructive pulmonary disease
DAS28‐CRP3 = disease activity score with 28 joints and C‐reactive protein; DMARD = disease‐modifying antirheumatic drug; IQR = interquartile range; MDHAQ = multi‐dimensional health assessment questionnaire; MET‐hours/week = metabolic equivalent of tast in hours per week; MRC = Medical Research Council; RA, rheumatoid arthritis; SD = standard deviation.