Table 2.
Trends in multimorbidity of patients with knee osteoarthritis (OA) in the Intego registry (1996–2015)
| Variables | 1996–2000 | 2001–2005 | 2006–2010 | 2011–2015* | P value** |
| Mean age (±SD) | 55.3 (21.9) | 57.6 (20.5) | 57.8 (19.8) | 56.9 (19.8) | 0.384 |
| Women, n (%) | 972 (65%) | 1234 (65%) | 1419 (64%) | 1412 (62%) | 0.05224 |
| Incidence, n | 1503 | 1912 | 2202 | 2288 | |
| Multimorbidity, n (%) | |||||
| Hypertension | 359 (24%) | 485 (25%) | 623 (28%) | 593 (26%) | 0.0756 |
| Diabetes | 93 (6%) | 161 (8%) | 252 (11%) | 346 (15%) | <0.001 |
| CV events | 323 (21%) | 480 (25%) | 597 (27%) | 614 (27%) | <0.001 |
| GI complication (ulcer) | 28 (2%) | 60 (3%) | 59 (3%) | 61 (3%) | 0.3585 |
| Renal failure | 23 (2%) | 70 (4%) | 71 (3%) | 66 (3%) | 0.1025 |
| Depression | 141 (9%) | 230 (12%) | 259 (12%) | 287 (13%) | 0.009 |
| Obesity | 74 (5%) | 101 (5%) | 145 (7%) | 191 (8%) | <0.001 |
| Osteoporosis | 57 (4%) | 81 (4%) | 107 (5%) | 103 (5%) | 0.2303 |
| Cancer | 29 (2%) | 60 (3%) | 59 (3%) | 61 (3%) | <0.001 |
| Asthma | 125 (8%) | 205 (11%) | 328 (15%) | 392 (17%) | <0.001 |
| Substance abuse | 4 (0%) | 22 (1%) | 31 (1%) | 48 (2%) | <0.001 |
| Disease burden, n (±SD)*** | 1.63 (1.81) | 1.84 (2.00) | 2.18 (2.20) | 2.34 (2.35) | <0.001 |
Multimorbidity was measured for all incident cases with knee OA (ie, at the time when knee OA was registered as a diagnosis).
*Four time intervals of 5 years were defined to evaluate trends for all incident patients with knee OA.
†P-value for multimorbidity was calculated with the Cochran-Armitage trend test; p-value for age was calculated with the Jonckheere-Terpstra trend test.
‡The full list of diseases to calculate this mean disease burden is presented in online supplementary file 2.
CV, cardiovascular; GI, gastrointestinal.