Table 1. Baseline characteristics in the radiographic cohort.
| Negative (n=47) |
Single-positive (n=48) |
Double-positive (n=29) |
Triple-positive (n=97) |
p-value (triple-positive vs single-positive) |
|
|---|---|---|---|---|---|
| Demographic characteristics | |||||
| Sex | |||||
| Female | 34 (72%) | 36 (75%) | 21 (72%) | 57 (59%) | 0·056* |
| Male | 13 (28%) | 12 (25%) | 8 (28%) | 40 (41%) | .. |
| Ethnicity | |||||
| White | 47 (100%) | 48 (100%) | 28 (97%) | 97 (100%) | .. |
| Indian subcontinent | 0 | 0 | 1 (3%) | 0 | .. |
| Age at recruitment, years | 63·7 (12·4) | 56·6 (13·7) | 54·4 (15·0) | 57·8 (12·6) | 0·61 |
| Smoking status | |||||
| Ever smoked | 22 (47%) | 33 (69%) | 17 (59%) | 67 (69%) | .. |
| Never smoked | 25 (53%) | 15 (31%) | 12 (41%) | 30 (31%) | 0·97* |
| Alcohol intake, units per week | 5·1 (7·5) | 5·1 (11·3) | 4·9 (7·2) | 7·1 (15·7) | 0·29 |
| Disease characteristics | |||||
| Disease duration, months | 14·1 (41·1) | 12·0 (13·5) | 15·3 (27·5) | 13·3 (19·2) | 0·61 |
| Swollen joints (0-28) | 7·5 (5·6) | 6·7 (5·8) | 5·2 (3·6) | 7·0 (4·8) | 0·33 |
| Tender joints (0-28) | 12·1 (6·8) | 9·6 (7·3) | 8·4 (7·3) | 10·2 (7·3) | 0·66 |
| Erythrocyte sedimentation rate, mm/h | 33·2 (26·3) | 27·5 (20·9) | 37·2 (27·8) | 31·8 (22·6) | 0·37 |
| Patients with complete data | 39 | 40 | 27 | 84 | .. |
| C-reactive protein blood concentration, mg/L |
24·7 (28·6) | 14·8 (12·0) | 29·6 (36·7) | 24·6 (38·1) | 0·84 |
| Patients with complete data | 41 | 43 | 25 | 83 | .. |
| HAQ-DI score (0-3) | 1·3 (0·8) | 1·1 (0·8) | 1·2 (0·8) | 1·1 (0·8) | 0·86 |
| Patients with complete data | 47 | 48 | 29 | 96 | .. |
| HADS score (0-42) | 12·5 (7·4) | 13·1 (7·8) | 11·8 (8·7) | 11·7 (7·3) | 0·36 |
| Depression (0-21) | 6·3 (3·9) | 5·7 (3·7) | 5·4 (4·2) | 5·3 (3·7) | 0·44 |
| Anxiety (0-21) | 6·2 (4·2) | 7·3 (4·7) | 6·3 (4·9) | 6·4 (4·4) | 0·30 |
| Patients with complete data | 46 | 47 | 29 | 96 | .. |
| EQ-5D score | 0·45 (0·30) | 0·46 (0·36) | 0·52 (0·36) | 0·52 (0·31) | 0·42 |
| Patients with complete data | 47 | 48 | 29 | 96 | .. |
| PtGA VAS (0-100mm) | 51·1 (26·0) | 46·3 (24·7) | 48·9 (24·5) | 49·9 (27·1) | 0·42 |
| Rheumatoid factor | |||||
| High positive (>60 IU) | 3 (6%) | 21 (44%) | 13 (45%) | 43 (44%) | .. |
| Low positive (>20 IU) | 7 (15%) | 5 (10%) | 4 (14) | 25 (26%) | .. |
| Negative | 37 (79%) | 22 (46%) | 12 (41%) | 29 (30%) | 0·059* |
| Cyclic citrullinated peptide | |||||
| High positive (>60 AU) | 0 | 34 (71%) | 27 (93%) | 95 (98%) | .. |
| Low positive (>20 AU) | 0 | 14 (29%) | 2 (7%) | 2 (2%) | <0·0001* |
| Negative | 47 (100%) | 0 | 0 | 0 | .. |
| DAS28-ESR (0·0-9·4) | 5·4 (1·2) | 4·8 (1·4) | 4·9 (1·5) | 5·2 (1·4) | 0·16 |
| Patients with complete data | 39 | 40 | 27 | 84 | .. |
| DAS28-CRP (0·0-9·4) | 5·0 (1·5) | 4·5 (1·2) | 4·5 (1·8) | 4·7 (1·7) | 0·23 |
| Patients with complete data | 41 | 43 | 25 | 83 | .. |
| Radiographic scores | |||||
| Erosion score (0-280) | 3·9 (6·6) | 2·3 (4·1) | 2·1 (3·8) | 4·0 (8·5) | 0·55 |
| Joint space narrowing score (0-168) | 4·7 (5·0) | 3·25 (6·2) | 2·5 (4·7) | 3·9 (7·9) | 0·66 |
| Total SvH score (0-448) | 8·6 (10·7) | 5·6 (9·3) | 4·6 (7·4) | 7·9 (15·5) | 0·86 |
Data are n (%) or mean (SD), unless otherwise stated. The Mann-Whitney-Wilcoxon U test was used to calculate p-values for the difference between the single-positive group and the triple-positive group. p-values less than 0·05 were considered significant. For the swollen joint count, a score of 0 represents no swollen joints and a score of 28 represents swelling in all joints assessed. For the tender joint count, a score of 0 represents no tender joints and a score of 28 represents tenderness in all joints assessed. A HAQ-DI score of 0 indicates no disability and a score of 3 indicates severe disability. The score range for the HADS is 0–42, where the cutoff is 15 or more for a diagnosis of psychosocial distress. For both the anxiety and depression components of the HAD, the score range is 0–21, where the cutoff of 8 or more suggests the presence of anxiety or depression. For PtGA VAS, a score of 0 represents the lowest disease activity and a score of 100 represents the worst disease activity. For DAS28-ESR and DAS28-CRP, a score of more than 5·1 indicates high disease activity, a score of 3·2–5·1 indicates moderate disease activity, a score of 2·6–3·2 indicates low disease activity, and a score less than 2·6 indicates remission. The erosion score per joint ranges from 0 to 10. A total score of 0 represents no erosion of the hands and feet. A total score of 280 represents maximal total erosion. The joint space narrowing score per joint ranges from 0 to 4. A total score of 0 represents no joint space narrowing in the hands and feet. A total score of 168 represents maximal total joint space narrowing. The total SvH score is the sum of the total erosion score and the total joint space narrowing score. ACPAs=anti-citrullinated peptide antibodies. DAS28-CRP=Disease activity score of 28 joints with C-reactive protein.DAS28-ESR=Disease activity score of 28 joints with erythrocyte sedimentation rate. HADS=Hospital Anxiety and Depression Scale. HAQ-DI=Health Assessment Questionnaire Disability Index. PtGA VAS=patient global assessment of disease activity visual analog scale. SvH=Sharp-van der Heijde.
Denotes Egon Pearson N-1 corrected χ2 test for proportions.19