Univariate analysis

Multivariable analysis

Risk ratio (95% CI)

P-value

Risk ratio (95% CI)

P-value

Age (years old)

< 50

1.00 (referent)

≥ 50

1.88 (0.77 - 4.59)

0.169

Parity

0

1.00 (referent)

≥1

1.66 (0.93 - 2.95)

0.084

Menstrual cycle

Irregular

1.00 (referent)

Regular

0.89 (0.51 - 1.56)

0.676

BMI

< 25

1.00 (referent)

≥ 25

0.73 (0.34 - 1.53)

0.398

Depth (mm)

< 15

1.00 (referent)

1.00 (referent)

≥ 15

1.95 (1.18 - 3.21)

0.009^a)

1.89 (1.12 - 3.20)

　0.017^a)

Duration of

< 7

1.00 (referent)

1.00 (referent)

catheter insertion (days)

≥ 7

0.93 (0.87 - 0.98)

0.014^a)

0.92 (0.87 - 0.98)

　0.011^a)