Table 1

Distribution of selected characteristics between cases and fertile controls

Variables

Controls

(n = 480)

Case 1a

(n = 524)

Case 2b

(n = 768)




N (%)

N (%)

Pd

N (%)

Pd


Age (mean ± SEM)

28.1 ± 0.16

28.3 ± 0.16

0.374

28.3 ± 0.14

0.355

Smoking stauts

Never

278 (57.9)

238 (45.4)

< 0.001

363 (47.3)

< 0.001

Ever

202 (42.1)

286 (54.6)

405 (52.7)

Pack-years (mean ± SEM)c

4.3 ± 0.21

5.2 ± 0.20

0.002

4.9 ± 0.14

0.014

Drinking status

Never

425 (88.5)

447 (85.3)

0.129

667 (86.8)

0.377

Ever

55 (11.5)

77 (14.7)

101 (13.2)

Semen parameters (mean ± SEM)

Concentration (× 106 /ml)

102.6 ± 3.07

5.12 ± 0.38

< 0.001

73.6 ± 2.12

< 0.001

Motility (%)

65.3 ± 0.58

3.26 ± 0.27

< 0.001

37.9 ± 0.55

< 0.001

Volume (ml)

2.80 ± 0.07

2.37 ± 0.07

< 0.001

2.78 ± 0.05

0.818

Sperm DNA fragmentation (%)

n. d.

n. d.

19.5 ± 0.82


aCase 1: idiopathic infertile men with azoospermia or oligozoospermia.

bCase 2: idiopathic infertile men with normal sperm count.

cAmong ever smokers.

dP-values were derived from the χ2 test for categorical variables (smoking and drinking status) and t test for continuous variables (age and pack-years).

n. d.: not detected.

Ji et al. BMC Medicine 2012 10:49   doi:10.1186/1741-7015-10-49

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