ORs and 95% CIs for the association of vasectomy with risk of prostate cancer, King County, Washington, 1993–1996
| Vasectomy status | No. (%) of cases | No. (%) of controls | ORa | 95% CI |
|---|---|---|---|---|
| Ever | ||||
| No | 456 (60.6) | 438 (62.3) | 1.00b | |
| Yes | 297 (39.4) | 265 (37.7) | 1.10 | 0.9 –1.4 |
| Age at vasectomy | ||||
| 20–29 yrs | 49 (6.5) | 47 (6.7) | 1.15 | 0.7 –1.8 |
| 30–34 yrs | 84 (11.2) | 66 (9.4) | 1.30 | 0.9 –1.9 |
| 35–39 yrs | 82 (10.9) | 74 (10.5) | 1.07 | 0.7 –1.6 |
| ≥40 yrs | 82 (10.9) | 77 (11.0) | 0.96 | 0.7 –1.4 |
| Trend testd | P = 0.24 | |||
| Years since vasectomyc | ||||
| <5 | 8 (1.1) | 10 (1.4) | 0.68 | 0.2 –1.9 |
| 5–9 | 14 (1.9) | 21 (3.0) | 0.68 | 0.3 –1.5 |
| 10–14 | 30 (4.0) | 35 (5.0) | 0.94 | 0.5 –1.6 |
| 15–19 | 63 (8.4) | 58 (8.3) | 1.11 | 0.7 –1.7 |
| 20–24 | 81 (10.8) | 64 (9.1) | 1.11 | 0.8 –1.6 |
| 25–29 | 63 (8.4) | 46 (6.5) | 1.42 | 0.9 –2.2 |
| ≥30 | 38 (5.0) | 30 (4.3) | 1.23 | 0.7 –2.1 |
| Trend testd | P = 0.11 | |||
| Year of vasectomy | ||||
| 1952–1968 | 81 (10.8) | 61 (8.7) | 1.37 | 0.9 –2.0 |
| 1969–1974 | 100 (13.1) | 80 (11.4) | 1.16 | 0.8 –1.7 |
| 1975–1979 | 62 (8.2) | 61 (8.7) | 1.01 | 0.7 –1.5 |
| 1980–1984 | 34 (4.5) | 31 (4.4) | 1.14 | 0.7 –1.9 |
| 1985–1989 | 8 (1.1) | 21 (3.0) | 0.38 | 0.1 –0.9 |
| 1990–1995 | 12 (1.6) | 10 (1.4) | 1.00 | 0.4 –2.6 |
| Trend testd | P = 0.09 |
a Adjusted for age (continuous), race, family history of prostate cancer (none, first-degree relative, second-degree relative only), and number of PSA blood tests within 5 years before the reference date (0, 1–2, 3–4, ≥5).
b Reference group for all ORs related to vasectomy.
c Analysis excludes one control with missing information.
d Trend test based on exposed subjects only.