Table 2.
Odds ratios (ORs) and 95% confidence intervals (CIs) of IUD characteristics and endometrial cancer risk
| Cases | Controls | OR (95% CI)1 | |
|---|---|---|---|
| n (%) | |||
| IUD use | |||
| Never user | 7368 (83.7) | 13069 (85.1) | Ref |
| Ever user | 1433 (16.3) | 2288 (14.9) | 0.81 (0.74, 0.90) |
| IUD type2 | |||
| Never user | 2995 (73.7) | 2883 (66.8) | Ref |
| Copper | 108 (2.7) | 405 (9.4) | 0.89 (0.66, 1.21) |
| Inert | 385 (9.5) | 521 (12.1) | 0.69 (0.58, 0.82) |
| Hormone-releasing | 21 (0.5) | 12 (0.3) | 0.97 (0.44, 2.14) |
| Combination | 86 (2.1) | 140 (3.2) | 0.88 (0.65, 1.19) |
| pWald | 0.005 | ||
| Age at first IUD use3 | |||
| Never user | 4777 (84.0) | 9642 (84.1) | Ref |
| <25 | 125 (2.2) | 279 (2.4) | 0.84 (0.66, 1.06) |
| 25–29 | 321 (5.6) | 588 (5.1) | 0.74 (0.63, 0.87) |
| 30–34 | 325 (5.7) | 563 (4.9) | 0.72 (0.61, 0.86) |
| ≥35 | 131 (2.3) | 361 (3.1) | 0.53 (0.43, 0.67) |
| ptrend4 | 0.17 | ||
| Age at last IUD use5 | |||
| Never user | 3394 (83.0) | 7504 (74.5) | Ref |
| <30 | 85 (2.1) | 203 (2.3) | 0.73 (0.55, 0.97) |
| 30–39 | 206 (5.3) | 383 (4.3) | 0.92 (0.75, 1.13) |
| 40–44 | 101 (2.5) | 255 (2.9) | 0.58 (0.44, 0.75) |
| ≥45 | 276 (6.7) | 485 (5.5) | 0.60 (0.50, 0.72) |
| ptrend4 | 0.01 | ||
| Duration of use (years)6 | |||
| Never user | 5403 (81.6) | 9412 (82.7) | Ref |
| < 1 | 260 (3.9) | 399 (3.5) | 0.86 (0.68, 1.09) |
| 1–4 | 342 (5.2) | 565 (5.0) | 0.80 (0.68, 0.94) |
| 5–9 | 176 (2.7) | 262 (2.3) | 0.99 (0.80, 1.24) |
| ≥10 | 400 (6.0) | 694 (6.1) | 0.61 (0.52, 0.71) |
| ptrend4 | 0.16 | ||
| Time since last IUD use (years)7 | |||
| Never user | 3738 (83.6) | 7993 (86.3) | Ref |
| Within 1 year of study entry | 157 (3.5) | 337 (3.6) | 0.39 (0.30, 0.49) |
| 1–4 | 108 (2.4) | 136 (1.5) | 0.83 (0.62, 1.11) |
| 5–9 | 87 (1.9) | 117 (1.3) | 0.85 (0.62, 1.17) |
| ≥10 | 365 (8.2) | 645 (7.0) | 0.78 (0.67, 0.91) |
| ptrend4 | <0.0001 | ||
Adjusted for age (continuous), race (White, Black, Asian, Other), BMI (< 25kg/m2, 25–30 kg/m2, ≥30 kg/m2), age at menarche (<11, 11–12, 13–14, ≥15), duration of oral contraceptive use (never, <5, 5–9, ≥10 years), parity/age at last birth (nulliparous, 1–2 births and <25, 1–2 births and 25–29, 1–2 births and 30–34, 1–2 births and ≥35, ≥3 births and <25, ≥3 births and 25–29, ≥3 births and 30–34, ≥3 births and ≥35), menopausal status (premenopausal, postmenopausal), any menopausal hormone use (never, ever), smoking status (never, former, current), and stratified by study
Available in ANECS, CTS, FHCRC 1, FHCRC 2, SECS, US, WLHS
Available in ALBERTA, CTS, CECS, CPS-II, MILANO 1, MILANO 2, NYU, PEDS, SECS, SWEC, US, WLHS
p-value for trend was calculated using the Wald test for the ordinal variable based on the categories shown excluding never IUD users
Available in CECS, CPS-II, MILANO 1, MILANO 2, SECS, SWEC, US, WLHS
Available in ALBERTA, ANCES, CTS, CECS, CPS-II, MILANO 1, MILANO 2, NYU, PEDS, SECS, SWEC, US, WLHS
Available in ALBERTA, CECS, CPS-II, MILANO 1, MILANO 2, SECS, SWEC, US