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Table 1 Cohort characteristics

From: Opioid users show worse baseline knee osteoarthritis and faster progression of degenerative changes: a retrospective case-control study based on data from the Osteoarthritis Initiative (OAI)

Parameter

Opioid users

Controls

Cross-sectional

n

181

 

362

 

 Age (years; mean, SD)

60.4

9.4

60.4

8.3

 BMI (kg/m2; mean, SD)

29.6

5.0

29.6

5.0

 Sex

Male (n, %)

57

31.5

114

31.5

Female (n, %)

124

68.5

248

68.5

 Race

Asian (n, %)

1

0.6

2

0.6

White/Caucasian (n, %)

134

74.0

268

74.0

Black/African-American (n, %)

46

25.4

92

25.4

 Weak opioidsa (n = 94)

Tramadol (n, %)

62

34.3

  

Codeine (n, %)

23

12.7

  

Propoxyphene (n, %)

9

5.0

  

 Strong opioidsa (n = 87)

Hydrocodone (n, %)

57

31.5

  

Fentanyl (n, %)

1

0.6

  

Methadone (n, %)

3

1.7

  

Oxycodone (n, %)

22

12.2

  

Hydromorphone (n, %)

1

0.6

  

Morphine (n, %)

2

1.1

  

Oxymorphone (n, %)

1

0.6

  

 Outcome variables

    

  WORMSc

Total (mean, range)

11.6

(0–48)

18.9

(0–60)

Cartilage (mean, range)

5.7

(0–20)

8.3

(0–25)

Meniscus (mean, range)

1.9

(0–13)

3.6

(0–17)

BMEL (mean, range)

2.1

(0–9)

2.6

(0–12)

Subchondral cyst (mean, range)

1.0

(0–9)

1.9

(0–10)

  KOOSd

QOL (mean, range)

73.1

(6.3–100)

60.2

(0–100)

Symptom (mean, range)

90.0

(46.4–100)

83.4

(32.1–100)

Pain (mean, range)

88.6

(38.9–100)

78.6

(11.1–100)

Longitudinal

n

79

 

158

 

 Age (years; mean, SD)

59.6

8.8

59.6

8.7

 BMI (kg/m2; mean, SD)

28.2

4.8

28.2

4.8

 Sex

Male (n, %)

26

32.9

52

32.9

Female (n, %)

53

67.1

158

67.1

 Race

White/Caucasian (n, %)

60

76.0

120

76.0

Black/African-American (n, %)

19

24.1

38

24.1

 Weak opioidsa (n = 38)

Tramadol (n, %)

31

39.2

  

Codeine (n, %)

4

5.1

  

Propoxyphene (n, %)

3

3.8

  

 Strong opioidsa,b (n = 41)

Hydrocodone (n, %)

31

39.2

  

Fentanyl (n, %)

1

1.3

  

Oxycodone (n, %)

9

11.4

  
  1. aAccording to World Health Organization and British Pain Society criteria [20, 21]. bNo participant using methadone, hydromorphone, morphine, or oxymorphone was eligible to be included in the longitudinal cohort. cThe maximal possible WORMS total score was 96 and comprised cartilage (score 0–6 in six locations; maximal 36), meniscus (score 0–4, six locations; maximal 24), BMEL (score 0–3, six locations; maximal 18), and subchondral cyst (score 0–3, six locations; maximal 18) scores. A higher WORMS score indicates worse structural knee damage. dKOOS scores range from 0 to 100, with lower KOOS scores reflecting worse reported knee problems. BMI, body mass index; SD, standard deviation; WORMS, Whole-Organ Magnetic Resonance Imaging score; KOOS, Knee injury and Osteoarthritis Outcome Score; BMEL, bone marrow edema-like lesions; QOL, quality of life