Table 1 Characteristics of the Wuchuan County OA Study participants

Age, years; mean (SD)

57.3 (7.8)

56.2 (7.4)

62.7 (8.9)

< 0.001

Female

45%

54%

68%

< 0.001

BMI (kg/m²), mean (SD)

22.0 (3.1)

22.5 (3.1)

24.0 (4.0)

< 0.001

Back pain

29%

51%

43%

< 0.001

< 7 years' education

74%

72%

84%

0.04

Occupation, farming

93%

90%

83%

0.002

Still working

86%

89%

67%

< 0.001

SF-12 PCS, mean (SD)

49.9 (6.2)

49.9 (6.8)

49.3 (6.8)

0.7

SF-12 MCS, mean (SD)

52.3 (6.1)

53.4 (5.7)

54.6 (7.1)

0.004