Table IV.
Hazard ratios [HRs] and 95% CI for residential sun UV exposure in relation to endometriosis risk, NHSII cohort questionnaire cycles 1989–2015 (n = 95 080).
| Cases | Person-years | Age-adjusted HR 1 (95% CI) | Multivariable-adjusted HR 2 (95% CI) | |
|---|---|---|---|---|
| UV in state of residence at birth (mW/m2)3 | ||||
| <169.9 | 1010 | 244 193 | 1.00 (Reference) | 1.00 (Reference) |
| 169.9–189.1 | 1091 | 268 904 | 0.99 (0.91–1.08) | 1.01 (0.92–1.10) |
| 189.2–195.6 | 800 | 209 230 | 0.86 (0.78–0.94) | 0.79 (0.70–0.90) |
| 195.7–217.8 | 1345 | 369 190 | 0.90 (0.83–0.98) | 0.93 (0.85–1.01) |
| ≥217.9 | 392 | 118 072 | 0.82 (0.73–0.92) | 0.81 (0.72–0.92) |
| P trend | <0.0001 | 0.0001 | ||
| UV in state of residence at age 15 (mW/m2)3 | ||||
| <168.6 | 995 | 243 418 | 1.00 (Reference) | 1.00 (Reference) |
| 168.6–189.1 | 1118 | 267 900 | 1.04 (0.95–1.13) | 1.05 (0.96–1.14) |
| 189.2–198.8 | 790 | 205 244 | 0.87 (0.79–0.96) | 0.80 (0.70–0.91) |
| 198.9–217.8 | 1296 | 355 346 | 0.91 (0.84–0.99) | 0.95 (0.87–1.02) |
| ≥217.9 | 439 | 137 680 | 0.80 (0.71–0.90) | 0.79 (0.70–0.88) |
| P trend | <0.0001 | <0.0001 | ||
| UV in state of residence at age 30 (mW/m2)3 | ||||
| <166.2 | 943 | 251 846 | 1.00 (Reference) | 1.00 (Reference) |
| 166.2–175.7 | 887 | 239 366 | 0.98 (0.89–1.08) | 0.97 (0.88–1.06) |
| 175.8–176.8 | 932 | 238 626 | 0.92 (0.84–1.02) | 0.85 (0.74–0.96) |
| 176.9–200.8 | 1039 | 256 847 | 1.07 (0.97–1.17) | 1.05 (0.95–1.15) |
| ≥200.9 | 837 | 222 904 | 0.99 (0.90–1.09) | 0.90 (0.82–0.99) |
| P trend | 0.56 | 0.21 | ||
| Cumulative average UV (mW/m2)3 | ||||
| <166.6 | 1351 | 304 655 | 1.00 (Reference) | 1.00 (Reference) |
| 166.6–173.6 | 823 | 235 891 | 0.99 (0.90–1.08) | 0.99 (0.91–1.09) |
| 173.7–182.8 | 844 | 243 296 | 0.97 (0.88–1.05) | 0.98 (0.90–1.07) |
| 182.9–209.8 | 990 | 240 825 | 1.11 (1.02–1.21) | 1.08 (0.99–1.18) |
| ≥209.9 | 691 | 203 342 | 0.95 (0.86–1.04) | 0.86 (0.78–0.95) |
| P trend | 0.68 | 0.15 | ||
| Latitude in state of birth | ||||
| <40 degrees | 1713 | 420 572 | 1.00 (Reference) | 1.00 (Reference) |
| ≥40 degrees | 2371 | 633 501 | 0.93 (0.87–0.99) | 0.97 (0.91–1.03) |
| Latitude in state of residence at age 15 | ||||
| <40 degrees | 1753 | 433 995 | 1.00 (Reference) | 1.00 (Reference) |
| ≥40 degrees | 2352 | 631 084 | 0.93 (0.88–0.99) | 0.98 (0.92–1.04) |
| Latitude in state of residence at age 30 | ||||
| <40 degrees | 1933 | 484 229 | 1.00 (Reference) | 1.00 (Reference) |
| ≥40 degrees | 2009 | 540 860 | 0.93 (0.88–1.00) | 1.00 (0.94–1.07) |
Adjusted for current age (continuous months) and calendar time (2-year questionnaire period).
Additionally adjusted for body mass index at age 18 (<18.5, 18.5–22.4, 22.5–24.9 or ≥25 kg/m2), age at menarche (≤11, 12–13 or ≥14 years), menstrual cycle length (≤25, 26–31, 32–39 or ≥40 days), menstrual cycle pattern (regular, usually irregular, always irregular, no menses), parity (nulliparous, or 1, 2, 3 or ≥4 pregnancies lasting ≥6 months), oral contraceptive use (never, past or current use), smoking status (never, past or current smoking), childhood skin’s reaction to sun exposure, number of moles on leg, natural hair colour, annual income (<$75k, 75 to <100k, ≥100k), self-reported social standing in community (high, medium, low), tanning bed use combined HS/college and at ages 25–35 (none, <2 times a year, ≥3 times a year in high school and college only, ≥3 times a year at ages 25–35 only, ≥3 times a year in HS/college at 25–35 years) and predicted vitamin D.
Milliwatts/metre2.