Subjects

Control group (n = 150)

Observation group (n = 150)

χ²

P

Gender

1.396

0.237

Male

86 (57.3)

96 (64)

Female

64 (42.7)

54 (36)

Age/years old

0.892

0.639

<40

85 (52.6)

78 (34.5)

40 - 65

56 (42.1)

64 (55.2)

>65

9 (5.3)

8 (10.3)