Table 3

Odds ratios [95%CI] for all independent variables associated with four knee OA outcomes

Men

Women

Postmenopausal women

Radiographic knee OA

n = 1,053

n = 1,574

n = 1,330

Education (low)

1.21 [0.85, 1.71]

1.48 [1.12, 1.96]

1.33 [0.98, 1.79]

Physical activity (high)

1.04 [0.76, 1.42]

1.03 [0.80, 1.31]

0.99 [0.76, 1.30]

Occupation, PD

1.04 [0.74, 1.47]

0.86 [0.65, 1.14]

0.99 [0.73, 1.34]

Age 55-64

2.30 [1.51, 3.51]

1.46 [1.06, 2.02]

1.46 [1.00, 2.12]

Age 65-74

4.39 [2.87, 6.72]

2.71 [1.92, 3.84]

2.48 [1.66, 3.72]

Age 75 and over

5.48 [3.12, 9.65]

7.13 [4.67, 10.9]

6.26 [3.87, 10.1]

African American

1.31 [0.92, 1.85]

0.92 [0.71, 1.20]

0.79 [0.59, 1.04]

Knee injury

2.82 [1.97, 4.05]

1.69 [1.24, 2.31]

1.74 [1.25, 2.42]

BMI/5

1.35 [1.16, 1.58]

1.71 [1.55, 1.89]

1.68 [1.51, 1.87]

Current smoking

0.60 [0.41, 0.89]

0.91 [0.63, 1.31]

0.87 [0.58, 1.29]

Current alcohol

1.11 [0.79, 1.57]

0.62 [0.41, 0.95]

0.66 [0.42, 1.05]

Current HRT

N/A

N/A

0.58 [0.41, 0.83]

Bilateral radiographic knee OA

n = 908

n = 1,338

n = 1,132

Education (low)

1.06 [0.67, 1.68]

1.62 [1.12, 2.36]

1.53 [1.03, 2.27]

Physical activity (high)

0.86 [0.57, 1.30]

1.02 [0.73, 1.41]

0.99 [0.70, 1.40]

Occupation, PD

1.40 [0.87, 2.25]

0.75 [0.52, 1.10]

0.81 [0.55, 1.21]

Age 55-64

4.48 [2.35, 8.55]

2.04 [1.28, 3.26]

1.87 [1.09, 3.22]

Age 65-74

8.38 [4.38, 16.0]

4.60 [2.81, 7.55]

3.92 [2.21, 6.94]

Age 75 and over

10.6 [4.68, 23.9]

13.6 [7.64, 24.2]

10.7 [5.60, 20.6]

African American

1.81 [1.16, 2.83]

1.08 [0.77, 1.52]

0.91 [0.63, 1.30]

Knee injury

2.42 [1.49, 3.94]

1.71 [1.15, 2.55]

1.62 [1.06, 2.48]

BMI/5

1.46 [1.17, 1.82]

2.08 [1.82, 2.37]

2.03 [1.76, 2.35]

Current smoking

0.59 [0.35, 0.99]

0.79 [0.46, 1.35]

0.69 [0.38, 1.24]

Current alcohol

1.20 [0.76, 1.90]

0.76 [0.43, 1.34]

0.93 [0.52, 1.68]

Current HRT

N/A

N/A

0.44 [0.26, 0.74]

Symptomatic knee OA

n = 1,052

n = 1,571

n = 1,327

Education (low)

1.86 [1.20, 2.87]

1.64 [1.16, 2.31]

1.46 [1.01, 2.09]

Physical activity (high)

0.83 [0.57, 1.22]

1.23 [0.90, 1.66]

1.22 [0.88, 1.68]

Occupation, PD

0.86 [0.56, 1.33]

1.01 [0.72, 1.44]

1.06 [0.74, 1.53]

Age 55-64

2.45 [1.40, 4.27]

2.36 [1.53, 3.64]

2.14 [1.30, 3.52]

Age 65-74

4.33 [2.49, 7.55]

3.28 [2.05, 5.26]

2.95 [1.72, 5.06]

Age 75 and over

4.83 [2.35, 9.92]

12.2 [7.18, 20.8]

10.9 [5.94, 19.9]

African American

1.13 [0.73, 1.75]

0.81 [0.59, 1.12]

0.70 [0.49, 0.98]

Knee injury

4.05 [2.68, 6.11]

2.77 [1.96, 3.92]

2.63 [1.82, 3.78]

BMI/5

1.57 [1.30, 1.90]

1.90 [1.69, 2.14]

1.88 [1.66, 2.14]

Current smoking

0.86 [0.54, 1.37]

1.22 [0.76, 1.96]

1.12 [0.68, 1.86]

Current alcohol

1.40 [0.92, 2.14]

0.52 [0.29, 0.94]

0.57 [0.31, 1.07]

Current HRT

N/A

N/A

0.75 [0.48, 1.17]

Bilateral symptomatic knee OA

n = 943

n = 1,403

n = 1,172

Education (low)

0.90 [0.43, 1.88]

1.87 [1.13, 3.11]

1.84 [1.07, 3.16]

Physical activity (high)

0.81 [0.42, 1.60]

0.96 [0.61, 1.51]

0.97 [0.60, 1.57]

Occupation, PD

1.87 [0.86, 4.06]

0.84 [0.50, 1.39]

0.85 [0.49, 1.45]

Age 55-64

5.40 [1.68, 17.4]

3.40 [1.69, 6.85]

3.99 [1.64, 9.74]

Age 65-74

9.64 [3.03, 30.7]

5.10 [2.41, 10.8]

4.92 [1.91, 12.7]

Age 75 and over

16.9 [4.42, 64.5]

18.2 [7.92, 41.9]

16.8 [6.04, 46.6]

African American

1.13 [0.54, 2.37]

0.89 [0.56, 1.42]

0.81 [0.49, 1.33]

Knee Injury

2.19 [1.03, 4.65]

2.11 [1.26, 3.52]

1.79 [1.03, 3.12]

BMI/5

1.81 [1.31, 2.50]

2.20 [1.86, 2.60]

2.12 [1.76, 2.54]

Current smoking

0.77 [0.33, 1.77]

1.33 [0.65, 2.72]

1.23 [0.57, 2.68]

Current alcohol

1.51 [0.73, 3.14]

0.62 [0.26, 1.48]

0.78 [0.32, 1.89]

Current HRT

N/A

N/A

0.48 [0.22, 1.06]

Results are taken from the fully adjusted models as presented for education in Table 2

PD, Physically Demanding (Occupation); Low educational attainment, <12 years; Occupationally related Physical Activity Score, high is ≥ 10 on a scale of 0-16 for lifting, standing, walking, and squatting.

BMI/5 is the continuous, model variable; the OR represents an increase of 5 units of BMI.

The referent class for age is 45-54 years.

Callahan et al. Arthritis Research & Therapy 2010 12:R46   doi:10.1186/ar2956