Characteristics | Cases n=180 | Controls n=720 |
Women* | 103 (57%) | 412 (57%) |
Median (IQR) age in years* | 73 (65–80) | 73 (65–80) |
Median (IQR) time since entry into the cohort (years) | 5.1 (2.4–8.4) | 4.3 (2.1–7.1) |
Median (IQR) time since diagnosis (years) | 13.0 (6.2–21.4) | 7.8 (3.5–14.4) |
Serostatus by diagnosis code | ||
Seropositive RA | 136 (76%) | 476 (66%) |
Seronegative RA | 36 (20%) | 210 (29%) |
Missing | 8 (4%) | 34 (5%) |
Bone erosions† | ||
Erosive disease | 87 (48%) | 278 (39%) |
Non-erosive disease | 31 (17%) | 236 (33%) |
Missing | 62 (34%) | 206 (29%) |
Disease activity (CDAI score)‡ | ||
Remission (0.0–2.8) | 34 (19%) | 212 (29%) |
Low activity (2.9–10.0) | 67 (37%) | 313 (44%) |
Moderate activity (10.1–22.0) | 52 (29%) | 115 (16%) |
High disease activity (22.1–76.0) | 18 (10%) | 47 (7%) |
Missing | 9 (5%) | 33 (5%) |
Functional status (HAQ score)§ | ||
Mild to moderate difficulty (0.0–0.875) | 71 (39%) | 429 (60%) |
Moderate to severe disability (1.0–1.875) | 51 (28%) | 196 (27%) |
Severe to very severe disability (2.0–3.0) | 50 (28%) | 74 (10%) |
Missing | 8 (4%) | 21 (3%) |
csDMARD useß | ||
Non-user | 49 (27%) | 108 (15%) |
Former user | 22 (6%) | 41 (6%) |
Current user, monotherapy | 90 (50%) | 453 (63%) |
Current user, combination therapy | 19 (11%) | 118 (17%) |
Comorbidities | ||
Orthopaedic implant | 96 (53%) | 241 (34%) |
Cancer | 42 (23%) | 118 (16%) |
Diabetes mellitus | 38 (21%) | 88 (12%) |
Chronic obstructive pulmonary disease | 30 (17%) | 83 (12%) |
Chronic heart failure | 28 (16%) | 51 (7%) |
Vascular device or pacemaker | 17 (9%) | 53 (7%) |
Chronic liver disease | 12 (7%) | 18 (3%) |
Chronic dialysis treatment | 5 (3%) | ≤3 |
Solid organ transplantation | ≤3 | ≤3 |
HIV-positive | ≤3 | ≤3 |
Recent surgery | 69 (38%) | 37 (5%) |
≥1 inpatient procedure | 48 (27%) | ≤3 |
Highest attained educational level | ||
Basic school (<10 years) | 82 (46%) | 306 (42%) |
Upper secondary school | 5 (3%) | 10 (1%) |
Vocational education | 63 (35%) | 260 (36%) |
Short or medium length higher education | 21 (12%) | 110 (15%) |
Long-term higher education or research | 9 (5%) | 25 (4%) |
Missing | 0 (0%) | 9 (1%) |
Smoking status | ||
Never smoker | 40 (22%) | 184 (26%) |
Ever smoker | 80 (44%) | 319 (44%) |
Missing | 60 (33%) | 217 (30%) |
BMI level∑ | ||
Below normal (15.0–22.9 kg/m2) | 27 (15%) | 93 (13%) |
Normal (23.0–29.9 kg/m2) | 45 (25%) | 224 (31%) |
Above normal (30.0–50.0 kg/m2) | 25 (14%) | 74 (10%) |
Missing | 83 (46%) | 329 (46%) |
Cases comprised all patients with RA in DANBIO with a first-time S. aureus bacteraemia and controls were matched by age and sex. See figure 1 for information on biological antirheumatic treatment and glucocorticoids.
All presented values are n (%) unless stated otherwise. Exact numbers are not shown when n≤3 for discretion reasons. Methicillin-resistant S. aureus caused <1.7% (n≤3) of cases.
online supplemental table S1
*Matching variables.
†Erosive status was registered median 1 year before index (IQR 0–3 years before).
‡CDAI registered median 5 months before index (IQR 2–12 months).
§HAQ registered median 4 months before index (IQR 2–11 months).
¶Irrespective of concomitant use of biological antirheumatic drugs and glucocorticoids
**∑BMI cut-offs based on survival curves for elderly individuals, for details on BMI levels see online supplemental table S1).
BMI, body mass index; CDAI, Clinical Disease Activity Index; csDMARDs, conventional synthetic disease-modifying antirheumatic drug; HAQ, Health Assessment Questionnaire.