Table 1. Demographic and Clinical Characteristics of the Study Participants at Baseline.
| Baseline characteristics | No. (%) | ||
|---|---|---|---|
| Intensity | Control | ||
| High | Low | ||
| No. | 127 | 126 | 124 |
| Age, mean (SD), y | 67 (9) | 64 (8) | 64 (7) |
| Weight, mean (SD), kg | 89 (19) | 89 (18) | 89 (16) |
| Height, mean (SD), m | 1.68 (0.11) | 1.69 (0.10) | 1.68 (0.10) |
| BMI, mean (SD) | 31 (6) | 31 (6) | 32 (5) |
| Sex | |||
| Women | 52 (41) | 51 (41) | 48 (39) |
| Men | 75 (59) | 75 (59) | 76 (61) |
| Racea | |||
| White | 103 (81) | 99 (79) | 94 (76) |
| Black | 20 (16) | 24 (19) | 26 (21) |
| Asian | 2 (2) | 0 | 1 (1) |
| More than 1 race | 2 (2) | 3 (2) | 3 (2) |
| Ethnicity, No./total (%)a,b | |||
| Hispanic | 3/118 (3) | 2/120 (2) | 1/123 (1) |
| Annual household income, $b | |||
| No. | 123 | 124 | 121 |
| <20 000 | 10 (8) | 9 (7) | 7(6) |
| 20 000-34 999 | 14 (11) | 13 (10) | 10(8) |
| 35 000-49 999 | 17 (14) | 23 (19) | 17 (14) |
| 50 000-74 999 | 32 (26) | 23 (19) | 34 (28) |
| 75 000-99 999 | 23 (19) | 25 (20) | 19 (16) |
| ≥100 000 | 27 (22) | 31 (25) | 34 (28) |
| Educationb | |||
| No. | 124 | 124 | 122 |
| <High school | 0 | 2 (2) | 1 (1) |
| High school | 9 (7) | 17 (14) | 5 (4) |
| Vocational school | 11 (9) | 10 (8) | 9 (7) |
| Some college/community college | 34 (27) | 26 (21) | 33 (27) |
| College | 28 (23) | 34 (27) | 32 (26) |
| Post college | 13 (10) | 11 (9) | 8 (7) |
| Graduate degree | 29 (23) | 24 (19) | 34 (28) |
| Comorbid illness, No.c | 127 | 126 | 124 |
| Patellofemoral OA, severity, 1, 2 (mild-moderate)d | 108 (85.7) | 106 (84.1) | 109 (87.9) |
| Hypertension | 71 (56) | 64 (51) | 61 (49) |
| Obesity (BMI ≥30)e | 68 (54) | 66 (52) | 68 (55) |
| Arthritis in other joints | 30 (24) | 26 (21) | 18 (15) |
| Cardiovascular disease | 17 (13) | 8 (6) | 14 (11) |
| Type 2 diabetes | 12 (9) | 14 (11) | 14 (11) |
| Kellgren-Lawrence grade (most affected)f | |||
| 2 | 63 (50) | 64 (51) | 57 (46) |
| 3 | 50 (39) | 48 (38) | 57 (46) |
| 4 | 14 (11) | 14 (11) | 10 (8) |
| WOMAC, mean (SD)g | |||
| Pain (range 0-20) | 7.0 (2.7) | 7.4 (2.6) | 7.2 (2.7) |
| Function (range 0-68) | 25.5 (10.3) | 26.6 (10.7) | 25.0 (10.3) |
Abbreviations: BMI, body mass index, calculated as weight in kilograms divided by height in meters squared; JSW, joint space width; OA, osteoarthritis; OARSI, Osteoarthritis Research Society International; WOMAC, Western Ontario and McMaster Universities Osteoarthritic Index.
Reported on a self-administered demographics questionnaire.
Some variables had a small amount of missing data due to refusing to answer the question.
Reported on a self-administered health history questionnaire (with the exception of patellofemoral OA) as conditions diagnosed by a health care professional. With comorbid illnesses that could exclude patients from participation, final approval or denial for participation provided after patient evaluation by study physician.
Patellofemoral OA measured from skyline view radiograph using the OARSI scale (0, none; 1, mild; 2, moderate; 3, severe).17 Patients with severe (JSW, 3) patellofemoral OA were excluded. One patient was missing baseline skyline view radiographs.
Measured during screening visit.
The Kellgren-Lawrence scale ranges from 0 to 4. A grade of 2 or greater indicates definite osteoarthritis on posteroanterior weight-bearing radiograph. A grade of 2 indicates definite osteophytes and possible joint space narrowing; grade 3, multiple osteophytes, definite joint space narrowing, sclerosis, and possible bony deformity; and grade 4, large osteophytes, marked definite joint space narrowing, severe sclerosis, and definite bony deformity.
The WOMAC index consists of a self-administered questionnaire including 5 questions on pain, and 17 questions on physical function (scale for each question range, 0 no symptoms to 4 extreme symptoms). Composite scores for pain ranged from 0 to 20 and for function 0 to 68. Pain cut points are on a 0 to 20 scale: 2 to 8, mild; more than 8 to 14, moderate; more than 14 to 20, severe (transformed from 0-10 scale reported in26). A function score 21 or higher indicates physical work limitations.27