Table 1.
Baseline characteristics of 9004 RA patients identified in the Swedish Rheumatology Quality Register (SRQ), 2006–2016*
| Overall | AITD+† | AITD−† | |
|---|---|---|---|
| Characteristics | (n=9 004) | (n=1 003) | (n=8 001) |
| Sex | |||
| Women | 6072 (67.4) | 886 (88.3) | 5186 (64.8) |
| Men | 2932 (32.6) | 117 (11.7) | 2815 (35.2) |
| Age at inclusion in SRQ/index date‡ | 65.8 (15.0) | 68.3 (14.1) | 65.5 (15.1) |
| RA diagnosis§ | |||
| Seropositive RA | 6088 (67.6) | 694 (69.2) | 5394 (67.4) |
| Seronegative RA | 2687 (29.8) | 272 (27.1) | 2415 (30.2) |
| Unspecified RA | 229 (2.5) | 37 (3.7) | 192 (2.4) |
| Duration of symptoms (months) | 5.5 (3.3) | 5.5 (3.3) | 5.5 (3.3) |
| Year of inclusion in SRQ | |||
| 2006 | 690 (7.7) | 68 (6.8) | 622 (7.8) |
| 2007 | 699 (7.8) | 65 (6.5) | 634 (7.9) |
| 2008 | 747 (8.3) | 81 (8.1) | 666 (8.3) |
| 2009 | 914 (10.2) | 89 (8.9) | 825 (10.3) |
| 2010 | 812 (9.0) | 94 (9.4) | 718 (9.0) |
| 2011 | 835 (9.3) | 94 (9.4) | 741 (9.3) |
| 2012 | 891 (9.9) | 113 (11.3) | 778 (9.7) |
| 2013 | 872 (9.7) | 102 (10.2) | 770 (9.6) |
| 2014 | 834 (9.3) | 95 (9.5) | 739 (9.2) |
| 2015 | 846 (9.4) | 92 (9.2) | 754 (9.4) |
| 2016 | 864 (9.6) | 110 (11.0) | 754 (9.4) |
*Values are the number (%).
†First thyroxine prescription before RA diagnosis. Non-autoimmune cause for thyroxine prescription not excluded.
‡Mean (± SD years).
§According to the ICD 10 registered, assessed at the time of inclusion in the SRQ.
AITD, autoimmune thyroid disease; RA, rheumatoid arthritis.