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Table 3 Crude rate and relative risk of KR due to primary OA in 153,795 Norwegian men

From: Risk factors for knee replacement due to primary osteoarthritis, a population based, prospective cohort study of 315,495 individuals

 

No. of participants

Person-years

No. of knee replacements

KRs per 10,000 person-years (crude rate)

Multivariate adjusted RR* (95% CI)

Body Mass Index, kg/m 2

 

<23.3

38,967

470,734

32

0.7

1

23.4-25.1

38,099

460,094

79

1.7

2.35 (1.55-3.54)

25.2-27.2

38,918

469,847

93

2.0

2.58 (1.73-3.87)

> = 27.3

37,807

455,912

226

5.0

6.16 (4.23-8.95)

P (test for trend)

    

<0.0001

Physical activity at work

 

Sedentary

58,430

705,549

114

1.6

1

Moderate

43,757

528,129

132

2.5

1.51 (1.18-1.95)

Intermediate

32,304

389,973

90

2.3

1.64 (1.24-2.17)

Intensive

19,118

230,737

94

4.1

2.41 (1.83-3.18)

P (test for trend)

    

<0.0001

Physical activity at leisure

 

Sedentary

29,620

357,537

80

2.2

1

Moderate

80,762

974,895

245

2.5

1.02 (0.79-1.31)

Intermediate

38,982

470,681

98

2.1

0.96 (0.71-1.30)

Intensive

4,350

52,544

6

1.1

0.84 (0.36-1.94)

P (test for trend)

    

0.668

Height

 

< 174

44,106

532,390

126

2.4

1

175-178

36,438

439,896

111

2.5

1.38 (1.06-1.78)

179-182

35,289

426,040

91

2.1

1.33 (1.01-1.76)

> = 183

37,960

458,286

102

2.2

1.64 (1.25-2.15)

P (test for trend)

    

0.001

Smoking

 

Never smoker

46,945

566,770

126

2.2

1

Former smoker

41,371

499,259

161

3.2

1.00 (0.79-1.27)

Smoker

65,479

790,606

143

1.8

0.82 (0.64-1.04)

P (test for trend)

    

0.092

  1. *Adjusted for age at screening, height, smoking habits, BMI and physical activity at work, and at leisure time.