Table 2. Odds ratios (OR) and 95% confidence intervals (CI) of multinomial logistic regression analysis (trajectory of ‘no change in KOOS QoL’ as reference).
| OR (95% CI) | ||||
|---|---|---|---|---|
| Variable | Category | Improving KOOS QoL after decline | Slowly worsening KOOS QoL | Rapidly worsening KOOS QoL |
| Age (years) | 45–54 | 1.0 | 1.0 | 1.0 |
| 55–64 | 0.93 (0.67–1.29) | 0.98 (0.75–1.28) | 1.17 (0.83–1.65) | |
| 65–79 | 0.94 (0.66–1.36) | 1.07 (0.80–1.45) | 0.65 (0.44–0.97) | |
| Gender | Male | 1.0 | 1.0 | 1.0 |
| Female | 1.36 (1.02–1.83) | 1.11 (0.87–1.41) | 1.44 (1.05–1.98) | |
| BMIa | <25 | 1.0 | 1.0 | 1.0 |
| 25 to <30 | 1.51 (1.07–2.14) | 1.10 (0.84–1.44) | 1.92 (1.31–2.81) | |
| 30 to <35 | 2.02 (1.38–2.96) | 1.59 (1.18–2.14) | 3.23 (2.15–4.85) | |
| ≥35 | 2.31 (1.38–3.87) | 1.53 (0.98–2.39) | 2.04 (1.11–3.77) | |
| Race | White | 1.0 | 1.0 | 1.0 |
| Non-White | 0.93 (0.64–1.33) | 0.91 (0.67–1.24) | 0.74 (0.50–1.10) | |
| Socioeconomic status | ||||
| Education | Tertiary | 1.0 | 1.0 | 1.0 |
| Secondary | 0.97 (0.70–1.35) | 1.05 (0.80–1.37) | 1.01 (0.70–1.45) | |
| None/Primary | 0.99 (0.69–1.40) | 1.18 (0.88–1.57) | 1.20 (0.83–1.73) | |
| Income | $100k or greater | 1.0 | 1.0 | 1.0 |
| $50k to <$100k | 1.04 (0.74–1.46) | 1.02 (0.77–1.35) | 1.57 (1.06–2.33) | |
| $25k to <$50k | 0.79 (0.52–1.22) | 1.04 (0.74–1.47) | 1.84 (1.16–2.92) | |
| <$25k | 1.27 (0.75–2.16) | 1.20 (0.77–1.87) | 3.03 (1.73–5.33) | |
| Living status | Living with someone else | 1.0 | 1.0 | 1.0 |
| Living alone | 1.04 (0.74–1.45) | 1.02 (0.78–1.35) | 0.82 (0.57–1.16) | |
| Clinical characteristics of knee | ||||
| Knee pain severity | No pain (0–1) | 1.0 | 1.0 | 1.0 |
| Mild pain (2–3) | 1.17 (0.82–1.67) | 1.01 (0.76–1.34) | 1.50 (1.04–2.17) | |
| Moderate pain (4–10) | 1.72 (1.15–2.57) | 1.17 (0.84–1.62) | 1.96 (1.27–3.03) | |
| Knee injuries | No | 1.0 | 1.0 | 1.0 |
| Yes | 1.03 (0.77–1.37) | 1.02 (0.80–1.28) | 1.08 (0.80–1.47) | |
| Knee surgical history | No | 1.0 | 1.0 | 1.0 |
| Yes | 1.63 (1.12–2.38) | 1.44 (1.05–1.97) | 1.29 (0.83–2.01) | |
| KOOS QoLb | 1.04 (1.03–1.05) | 1.03 (1.02–1.04) | 1.06 (1.05–1.07) | |
| Other factors | ||||
| Charlson comorbidity index | 0 | 1.0 | 1.0 | 1.0 |
| ≥1 | 1.43 (1.05–1.94) | 1.07 (0.82–1.40) | 1.26 (0.90–1.77) | |
| PASEc | 238–526 | 1.0 | 1.0 | 1.0 |
| 176–237 | 1.09 (0.71–1.68) | 1.04 (0.74–1.45) | 1.44 (0.92–2.26) | |
| 135–175 | 1.19 (0.77–1.83) | 1.19 (0.86–1.67) | 1.29 (0.81–2.06) | |
| 91–134 | 1.23 (0.80–1.89) | 1.05 (0.75–1.48) | 1.12 (0.69–1.81) | |
| 0–90 | 1.11 (0.72–1.72) | 0.61 (0.42–0.89) | 1.33 (0.83–2.14) | |
| CES-Dd | <16 | 1.0 | 1.0 | 1.0 |
| ≥16 | 1.73 (1.11–2.69) | 1.54 (1.05–2.24) | 1.33 (0.80–2.22) | |
| Smoking | Never | 1.0 | 1.0 | 1.0 |
| Former | 1.13 (0.86–1.49) | 1.10 (0.87–1.38) | 1.15 (0.85–1.55) | |
| Current | 1.02 (0.62–1.68) | 1.34 (0.92–1.97) | 2.08 (1.32–3.28) | |
aBody Mass Index (kg/m2).
bQuality of Life subscale of the Knee injury and Osteoarthritis Outcome Score.
cPhysical Activity Scale for the Elderly.
dCenter for Epidemiologic Studies Depression Scale.