Characteristics of patients included in the analysis
| 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Number of cases | 3519 | 3727 | 3735 | 3665 | 3556 | 3600 | 3857 | 4020 | 2549 | 3172 | 3323 |
| Also seen in previous year (%) | 65 | 69 | 67 | 65 | 66 | 61 | 63 | 64 | 52 | 52 | 64 |
| Female | 79% | 78% | 78% | 79% | 79% | 79% | 79% | 79% | 76% | 76% | 76% |
| Mean±SD age (years) | 59.6±12.9 | 60.1±12.9 | 60.1±12.9 | 60.3±12.7 | 61.1±12.6 | 61.2±12.4 | 61.6±12.4 | 61.9±12.4 | 60.6±12.9 | 61.7±12.9 | 62.3±12.9 |
| Mean±SD disease duration (years) | 9.0±8.8 | 9.4±8.6 | 9.5±9.0 | 9.4±8.8 | 10.2±9.2 | 10.6±9.1 | 10.7±9.2 | 10.8±9.3 | 10.3±9.7 | 10.9±9.8 | 11.4±10.1 |
| Disease duration ≤2 years (%) | 18.9 | 15.3 | 16.9 | 17.6 | 13.2 | 11.3 | 11.7 | 13.4 | 18.7 | 15.4 | 14.3 |
| Disease duration >2–10 years (%) | 48.8 | 50.8 | 48.7 | 48.3 | 48.6 | 48.4 | 47.6 | 45.6 | 40.8 | 40.8 | 40.1 |
| Disease duration >10 years (%) | 32.3 | 33.9 | 34.4 | 34.1 | 38.2 | 40.3 | 40.7 | 41.0 | 40.5 | 43.8 | 45.6 |