Table 2.
Total, Direct, and Indirect Effect of Radiographic Knee OA Only, Knee Pain Only, and Symptomatic Knee OA on All-cause Mortality
| Neither Radiographic Knee OA nor Knee Pain (n=1,139) | Radiographic Knee OA Only (n=1,117) | Knee Pain Only (n=856) | Symptomatic Knee OA (n=1,387) | |
|---|---|---|---|---|
| Number of Death | 72 | 72 | 43 | 95 |
| Deaths per 1000 Person-years (95% CI) | 9.4 (7.4 to 11.8) | 14.1 (11.1 to 17.8) | 7.9 (5.7 to 10.6) | 15.7 (12.7 to 19.2) |
| Total Effect, HR (95% CI) | 1.0 (reference) | 2.6 (1.8 to 3.6) | 0.9 (0.6 to 1.3) | 2.6 (1.9 to 3.6) |
| Total Effect, HR (95% CI) * | 1.0 (reference) | 2.0 (1.4 to 2.9) | 0.9 (0.6 to 1.4) | 2.2 (1.6 to 3.1) |
| Disability Score | ||||
| Direct, HR (95% CI) * | 1.0 (reference) | 2.0 (1.7 to 2.4) | 0.9 (0.7 to 1.1) | 1.9 (1.6 to 2.3) |
| Indirect, HR (95% CI) * | 1.0 (reference) | 1.0 (0.9 to 1.2) | 1.0 (0.9 to 1.2) | 1.1 (1.0 to 1.4) |
| Mediation effect (%) | - | 2.0 | Not same direction | 22.4 |
| PCS of QoL | ||||
| Direct, HR (95% CI) * | 1.0 (reference) | 2.0 (1.7 to 2.4) | 0.9 (0.7 to 1.1) | 1.9 (1.6 to 2.2) |
| Indirect, HR (95% CI) * | 1.0 (reference) | 1.0 (0.8 to 1.2) | 1.1 (0.9 to 1.3) | 1.2 (1.0 to 1.4) |
| Mediation effect (%) | - | 0.0 | Not same direction | 26.5 |
| MCS of QoL | ||||
| Direct, HR (95% CI) * | 1.0 (reference) | 2.0 (1.7 to 2.4) | 0.9 (0.7 to 1.2) | 2.2 (1.9 to 2.6) |
| Indirect, HR (95% CI) * | 1.0 (reference) | 1.0 (0.8 to 1.2) | 1.0 (0.8 to 1.2) | 1.0 (0.8 to 1.2) |
| Mediation effect (%) | - | 0.0 | Not same direction | 0.0 |
| Oral Pain Medications Use | ||||
| Direct, HR (95% CI) * | 1.0 (reference) | 2.0 (1.7 to 2.4) | 0.9 (0.7 to 1.1) | 2.1 (1.7 to 2.5) |
| Indirect, HR (95% CI) * | 1.0 (reference) | 1.0 (0.9 to 1.2) | 1.0 (0.9 to 1.2) | 1.1 (0.9 to 1.3) |
| Mediation effect (%) | - | 2.0 | Not same direction | 12.0 |
n, number; OA, osteoarthritis; CI, confidence interval; HR, hazard ratio; PCS, physical component summary score; MCS, mental component summary score; QoL, quality of life.
*
Adjusted for age, race, sex, body mass index, education level, weekly alcohol consumption, smoking habits, history of knee injury, comorbidities, depressive symptoms and widespread pain.