Baseline characteristics (mean (SD) or number (%)) of the study population and the subgroups
| Baseline characteristics/factors | Total study population | H group | H&K group | HR group | No-HR group |
| Number of participants | 588 | 170 | 418 | 69 | 518 |
| Age (years), mean (SD) | 55.8 (±5.3) | 55.7 (±5.6) | 55.8 (±5.2) | 57.4 (±4.8) | 55.6 (±5.3) |
| Female, n (%) | 475 (81) | 129 (76) | 346 (83) | 48(70) | 426 (82) |
| Caucasian, n (%) | 578 (99) | 169 (99) | 409 (98)† | 68 (100) | 509 (98) |
| Body Mass Index (kg/m2), mean (SD) | 26.1 (±4.1)† | 25.5 (±3.5)† | 26.4 (±4.2)† | 25.8 (±3.8)† | 26.2 (±4.1)† |
Education level, n (%)
| †107 (19) 267 (47) 199 (35) | †25 (15) 776 (46) 65 (39) | †82 (20) 191 (47) 134 (33) | †16 (24) 33 (49) 18 (27) | †91 (18) 233 (46) 181 (36) |
| Never smoked, n (%) | 175 (30)† | 56 (34)† | 119 (29)† | 29 (43)† | 146 (29)† |
| No use of alcohol, n (%) | 125 (22)† | 30 (18)† | 95 (23)† | 17 (25)† | 108 (22)† |
| Use of any pain medication, n (%) | 250 (43)† | 63 (38)† | 187 (46)† | 29 (43)† | 221 (44)† |
| Three or more comorbidities, n (%) | 152 (26)† | 33 (20)† | 119 (29)† | 5 (7)† | 147 (29)† |
| Baseline NRS (0–10) past week, mean (SD) | 3.7 (±2.1)† | 3.4 (±2.2)† | 3.8 (±2.1)† | 4.1 (±2.4)† | 3.6 (±2.1)† |
| Baseline NRS (0–10) present pain, mean (SD) | 3.2 (±2.1)† | 2.8 (±2.0)† | 3.4 (±2.1)† | 3.8 (±2.4)† | 3.2 (±2.0)† |
| Morning stiffness in the hip <60 min, n (%) | 326 (55) | 101 (59) | 225 (54) | 43 (62) | 282 (54) |
| Knee pain, n (%) | 418 (71) | 0 (0) | 418 (100) | 31 (45) | 386 (75) |
| Physically active (>30 min) for three or more times a week, n (%) | 316 (55)† | 103 (62)† | 213 (53)† | 34 (52)† | 282 (56)† |
WOMAC, mean (SD)
| 5.4 (±3.4)† 2.8 (±1.7)† 17.2 (±12.0)† 26.4 (±16.8)† | 4.8 (±3.2)† 2.5 (±1.7)† 14.7 (±11.1)† 22.6 (±15.4)† | 5.7 (±3.5)† 2.9 (±1.7)† 18.3 (±12.2)† 28.0 (±17.1)† | 5.7 (±3.9)† 2.9 (±1.6)† 20.1 (±12.5)† 29.9 (±17.9)† | 5.4 (±3.4)† 2.8 (±1.7)† 16.9 (±11.9)† 26.0 (±16.6)† |
| Radiographic severity K/L grade ≥2 either hip, n (%) | 110 (19)† | 38 (23) † | 72 (17)† | 37 (54) | 73 (14)† |
| Radiographic severity K/L grade ≥2 either knee, n (%) | 76 (13)† | 14 (8)† | 62 (15)† | 12 (17) | 64 (13)† |
| Clinical hip OA,* either hip, n (%) | 160 (27)† | 51 (30)† | 109 (26)† | 34 (49) | 125 (24)† |
| Clinical knee OA,* either knee, n (%) | 206 (35)† | 0 | 206 (50)† | 12 (17) | 194 (38)† |
Physical examination, n (%)
| 322 (55)† 315 (54)† | 101 (60)† 94 (56)† | 221 (53)† 221 (54)† | 50 (73) 48 (71)† | 271 (53)† 267 (52)† |
Values are mean value±SD or percentages (%).
Participants can be part of two subgroups, for example, H group and HR group.
*According to the clinical criteria of the American College of Rheumatology.
†≤4.3% missing.
H, subgroup who reported hip pain only at baseline ; H&K, subgroup who reported hip and knee pain at baseline; HR, group who underwent a hip replacement during follow-up; K/L, Kellgren and Lawrence; NRS, Numerical Rating Scale; WOMAC, Western Ontario and McMaster Osteoarthritis Index.