Characteristics of chronic knee pain population according to presence of depressive symptoms
| Variables | Non-depressive (n=436) | Depressive (n=91) | P value |
| Age, years (mean±SD) | 65.9±9.2 | 67±8.8 | 0.4956 |
| Age, n (%) | |||
| 50–59 years | 94 (21.6) | 17 (18.7) | 0.8051 |
| 60–69 years | 152 (34.9) | 30 (33) | |
| ≥70 years | 190 (43.6) | 44 (48.4) | |
| Sex, n (%) | |||
| Male | 104 (23.9) | 13 (14.3) | 0.1181 |
| Female | 332 (76.2) | 78 (85.7) | |
| BMI, kg/m2, (mean±SD) | 24.4±3.3 | 23.8±3.1 | 0.1927 |
| Obesity, n (%) | |||
| Underweight (<18.5 kg/m2) | 9 (2.1) | 4 (4.4) | 0.1711 |
| Normal (18.5–24.9 kg/m2) | 246 (56.4) | 54 (60) | |
| Obese (≥25 kg/m2) | 181 (41.5) | 32 (35.6) | |
| Smoking status, n (%) | |||
| Non-smoker | 312 (73.8) | 71 (80.7) | 0.0372 |
| Ex-smoker | 71 (16.8) | 7 (8) | |
| Current smoker | 40 (9.5) | 10 (11.4) | |
| Alcohol consumption, n (%) | |||
| None | 183 (43) | 52 (59.1) | 0.2782 |
| One drink/month or less | 136 (31.9) | 20 (22.7) | |
| Two drinks/month to three drinks/week | 83 (19.5) | 10 (11.4) | |
| Four drinks/week or more | 24 (5.6) | 6 (6.8) | |
| Occupation, n (%) | |||
| Unemployed (student, housewife, etc) | 262 (60.1) | 66 (72.5) | 0.0561 |
| Office work/sales and services | 48 (11) | 5 (5.5) | |
| Agriculture, forestry and fishery | 42 (9.6) | 8 (8.8) | |
| Machine fitting and simple labour | 84 (19.3) | 12 (13.2) | |
| Household income, n (%) | |||
| Low | 171 (39.5) | 61 (67) | <0.0001 |
| Low–moderate | 112 (25.9) | 24 (26.4) | |
| Moderate–high/high | 150 (34.6) | 6 (6.6) | |
| Educational level, n (%) | |||
| ≤6 years | 278 (63.8) | 67 (73.6) | 0.0076 |
| 7–9 years | 58 (13.3) | 15 (16.5) | |
| ≥10 years | 100 (22.9) | 9 (9.9) | |
| Aerobic physical activity, n (%) | |||
| No | 254 (59.1) | 59 (67.8) | 0.0162 |
| Yes | 176 (40.9) | 28 (32.2) | |
| Duration of sleep, hours (mean) | 6.5±1.7 | 5.9±1.9 | 0.0325 |
The Rao-Scott χ2 test or t-test was performed to determine differences between groups with/without depressive symptoms. Missing values/non-responses were excluded from analysis. Individuals with PHQ-9 scores >10 were considered to have depressive symptoms. Levels of depressive symptoms were divided into five quartiles: none (0–4), mild (5–9), moderate (10–14), moderately severe (15–19) and severe (20–27) according to the PHQ-9 score.
BMI, body mass index; PHQ-9, Patient Health Questionnaire-9.