Table 1.
Baseline descriptive statistics of the study samples.
| Variable | The VIDEO trial (N = 474) follow-up 3 years | The OAI study (N = 4796) follow-up 9 years | ||||
|---|---|---|---|---|---|---|
| N | % | Mean (SD)/median (IQR) | N | % | Mean (SD)/median (IQR) | |
| Treatment | N/A | |||||
| Active | 237 | 50.0 | ||||
| Vitamin D | N/A | |||||
| Active | 232 | 22.9 (8.8)/21.9 (16.3-28.3) | ||||
| Placebo | 231 | 23.0 (8.0)/22.3 (16.7-28.8) | ||||
| Missing | 11 | 2.3 | ||||
| Age | 474 | 64.0 (7.6)/63.0 (58.0-69.0) | 4500 | 61.3 (9.2)/61.0 (53.0-69.0) | ||
| Missing | 0 | 296 | 6.2 | |||
| Sex | ||||||
| Women | 289 | 61.0 | 2804 | 58.5 | ||
| BMI | 473 | 29.4 (5.1)/28.7 (25.5-32.3) | 4792 | 28.6 (4.8)/28.3 (25.1-31.7) | ||
| Missing | 1 | 0.2 | 4 | 0.1 | ||
| Smoking | ||||||
| Current | 25 | 5.2 | 313 | 6.5 | ||
| Current-not regular | 10 | 0.2 | ||||
| Former | 214 | 45.2 | 1909 | 39.8 | ||
| Never smoked | 230 | 48.5 | 2564 | 53.5 | ||
| Missing | 5 | 1.1 | 0 | |||
| Alcohol use | ||||||
| Yes | 395 | 83.3 | 3821 | 79.7 | ||
| Missing | 0 | 0 | ||||
| Currently working | ||||||
| Yes | 198 | 41.8 | 2943 | 61.4 | ||
| Missing | 1 | 0.2 | 0 | |||
| Physical activity sport/hobby>1/month | N/A | |||||
| Yes | 224 | 47.3 | ||||
| Missing | 4 | 0.8 | ||||
| Depression | ||||||
| Beck Depression Inventory (score 0-63) | 473 | 2.0 (2.6)/1.0 (0.0-3.0) | ||||
| Centre for Epidemiological Studies Depression Scale (score 0-60) | 4731 | 6.6 (7.0)/4.0 (2.0-9.0) | ||||
| Missing | 1 | 0.2 | 65 | 1.4 | ||
| Quality of life WHOQoL-Bref (score 0-100) | N/A | |||||
| Physical domain | 468 | |||||
| Psychological domain | 468 | 64.5 (16.6)/64.3 (53.6-75.0) | ||||
| Social domain | 468 | 71.2 (14.3)/70.8 (62.5-79.2) | ||||
| Environmental domain | 468 | 71.9 (18.8)/75.0 (58.3-83.3) | ||||
| Missing | 6 | 1.3 | 77.4 (13.0)/78.1 (68.8-87.5) | |||
| Comorbidities | N/A | |||||
| None | 3631 | 75.7 | ||||
| One | 724 | 15.1 | ||||
| More than one | 441 | 9.2 | ||||
| Missing | 0 | |||||
| Medications use of analgesics, NSAIDs, and steroids | ||||||
| Yes | 273 | 57.6 | 1783 | 37.2 | ||
| Missing | 17 | 3.6 | 0 | |||
| Supplements use of glucosamine and chondroitin | ||||||
| Yes | 139 | 29.3 | 1625 | 33.9 | ||
| Missing | 17 | 3.6 | 0 | |||
| Kellgren–Lawrence grade (Index/Worse knee)* | ||||||
| 0 | 6 | 1.3 | 1260 | 26.3 | ||
| 1 | 121 | 25.5 | 697 | 14.5 | ||
| 2 | 178 | 37.6 | 1365 | 28.5 | ||
| 3 | 136 | 28.7 | 892 | 18.6 | ||
| 4 | 29 | 6.1 | 293 | 6.1 | ||
| Missing | 4 | 0.8 | 289 | 6.0 | ||
| Knee replacement at baseline | ||||||
| Yes | 63 | 1.3 | ||||
| Left | 25 | 0.5 | ||||
| Right | 38 | 0.8 | ||||
| No | 474 | 100.0 | 4733 | 98.7 | ||
| Missing | 0 | 0 | ||||
| Knee replacement during follow-up | ||||||
| Left | 271 | 5.7 | ||||
| Right | 277 | 5.8 | ||||
| Bilateral replacement | 2 | 0.4 | 119 | 2.5 | ||
| Index | 13 | 2.7 | ||||
| Contralateral | 30 | 6.3 | ||||
| Individuals with knee replacement by the end of the study† | ||||||
| Yes | 41 | 8.6 | 492 | 9.2 | ||
| No | 433 | 91.4 | 4357 | 90.8 | ||
| Mortality during follow-up | ||||||
| Yes | 5 | 1.1 | 305 | 6.4 | ||
*
The index knee refers to the VIDEO trial, and the Worse knee to the OAI study.
†
The summary of the previous 2 variables, knee replacement at baseline and during follow-up, showing information per person instead of per knee.
BMI, body mass index; IQR, interquartile range; N/A, not applicable or not assessed; NSAID, nonsteroidal anti-inflammatory drug; OAI, Osteoarthritis Initiative; WHOQoL-Bref, The World Health Organization Quality of Life Instrument.