General characteristics of the study cohorts.
| Characteristic | Ontario | Quebec |
|---|---|---|
| Study period | Jan 1, 2000 to Mar 1, 2013 | Jan 1, 2002 to Dec 31, 2011 |
| Cohort size, n | 20,918 | 6754 |
| Followup time, yrs | ||
| Median (IQR) | 4.6 (2.6–7.4) | 4.4 (2.6–6.7) |
| Maximum | 13.2 | 10.0 |
| Cumulative total | 110,274 | 32,177.1 |
| No. events, n (%) | 2201 (10.5) | 437 (6.5) |
| Description of events, frequency by joint site, n (%) | ||
| Knee | 1118 (50.8) | 236 (54.0) |
| Hip | 942 (42.8) | 185 (42.3) |
| Pelvis | 7 (0.3) | < 5 |
| Shoulder | 78 (3.5) | 15 (3.4) |
| Other small joints* | 56 (2.5) | < 5 |
| Event rate, per 100 patient-yrs | 2.0 | 1.4 |
| Distribution of event times, yrs | ||
| Median (IQR) | 3.2 (1.9–5.3) | 3.0 (1.9–4.4) |
| Maximum | 12.9 | 8.8 |
↵* Small joint defined as elbow, hand, wrist, ankle, and feet. Significant data are in bold face. IQR: interquartile range.