Table 4.
Nonparametric tests for baseline characteristics based on male age categories
| Variable | Group | Z-test | P-value | |||
|---|---|---|---|---|---|---|
| 1 (N=15) | 2 (N=369) | 3 (N=210) | 4 (N=42) | |||
| BMI (kg/cm2) | 18 (17.4–18.3) | 22.6 (21.2–24.3) | 26.5 (25.6–27.7) | 31.1 (30.4–32.9) | 6.719 | 0.081 |
| Infertility years | 2.25 (2–3) | 3 (2–4) | 4 (2.00–7.25) | 4 (2–6) | 58.124 | 0.000 |
| Sperm volume (ml) | 3.75 (2.73–4.80) | 3.60 (2.68–4.90) | 3.60 (2.55–4.60) | 3.2 (2.2–3.9) | 11.423 | 0.010 |
| Sperm concentration (106/ml) | 38.62 (24.85–63.00) | 41.55 (24.00–68.73) | 49.00 (26.64–83.16) | 42.76 (21.99–77.14) | 4.947 | 0.176 |
| Total sperm amount (106/ml) | 148.41 (84.74–243.90) | 153.18 (83.49–262.40) | 167.70 (96.46–265.30) | 148.80 (71.82–221.93) | 4.429 | 0.219 |
| Normal sperm morphology rate (%) | 3.0 (2.3–4.3) | 3.1 (2.4–4.0) | 3.4 (2.1–4.2) | 3.0 (2.0–4.0) | 0.545 | 0.909 |
| Progressive motility rate (%) | 38.06 (24.81–48.21) | 38.58 (26.93–50.00) | 35.50 (23.96–47.30) | 28.19 (17.36–45.13) | 16.629 | 0.001 |
| Total sperm motility (%) | 43.52 (29.04–57.65) | 46.15 (32.65–58.86) | 41.74 (30.43–56.97) | 33.53 (21.03–52.42) | 14.154 | 0.003 |
| FSH (IU/l) | 4.21 (2.98–5.60) | 4.02 (3.09–5.33) | 4.41 (3.35–5.70) | 5.86 (4.45–7.40) | 37.393 | 0.000 |
| LH (IU/l) | 3.12 (2.29–4.34) | 3.23 (2.29–4.52) | 3.22 (2.37–4.41) | 3.26 (2.46–4.66) | 0.221 | 0.974 |
| T (ng/ml) | 3.42 (2.68–4.64) | 3.34 (2.56–4.50) | 3.45 (2.60–4.72) | 3.03 (2.38–3.86) | 8.24 | 0.041 |
| PRL (ng/ml) | 8.88 (6.45–12.30) | 9.05 (6.47–11.79) | 6.87 (5.49–9.09) | 8.08 (6.47–12.29) | 21.81 | 0.000 |
| E2 (pg/ml) | 32.77 (24.90–41.33) | 31.10 (23.02–37.00) | 32.55 (24.04–40.20) | 29.07 (21.03–36.10) | 6.543 | 0.088 |
| TSI | 1.14 (0.72–1.57) | 1.08 (0.76–1.60) | 1.11 (0.72–1.62) | 0.98 (0.72–1.23) | 5.664 | 0.129 |
| TE2 | 0.11 (0.08–0.17) | 0.11 (0.09–0.16) | 0.11 (0.08–0.16) | 0.11 (0.08–0.16) | 1.979 | 0.577 |
TE2, testosterone–estradiol ratio, T/E2; TSI, testosterone secretion index, T/LH; Male age-based grouping was finally presented as: group 1 [median: 18.0; range (P25–P75): 17.4–18.3], group 2 [median: 22.6; range (P25–P75): 21.2–24.3], group 3 [median: 26.5; range (P25–P75): 25.6–27.7], and group 4 [median: 31.1; range (P25–P75): 30.4–32.9].