Table 2.
Age and multivariable-adjusted hazard ratios of ovarian cancer by area of perineal powder application (n = 61576): Women’s Health Initiative Observational Study, 1993–2012
| Variable | No. of cases | Person-years | Age-adjusted HR | P trend † | Multivariable HR* |
P trend † |
|---|---|---|---|---|---|---|
| (95% CI) | (95% CI) | |||||
| Powder use on genitals | ||||||
| Never | 247 | 457855 | 1.0 (referent) | .63 | 1.0 (referent) | .67 |
| Ever‡ | 181 | 304867 | 1.13 (0.93 to 1.37) | 1.12 (0.92 to 1.36) | ||
| Less than 9 years | 112 | 173118 | 1.24 (0.99 to 1.55) | 1.23 (0.98 to 1.54) | ||
| 10 or more years | 68 | 129647 | 0.98 (0.75 to 1.29) | 0.98 (0.75 to 1.29) | ||
| Powder use on sanitary napkins | ||||||
| Never | 336 | 590351 | 1.0 (referent) | .70 | 1.0 (referent) | .69 |
| Ever‡ | 93 | 172712 | 0.96 (0.76 to 1.21) | 0.95 (0.76 to 1.20) | ||
| Less than 9 years | 62 | 114305 | 0.98 (0.75 to 1.28) | 0.96 (0.73 to 1.26) | ||
| 10 or more years | 30 | 56174 | 0.93 (0.64 to 1.35) | 0.95 (0.65 to 1.37) | ||
| Powder use on diaphragm | ||||||
| Never | 373 | 661239 | 1.0 (referent) | .78 | 1.0 (referent) | .67 |
| Ever‡ | 52 | 97714 | 0.94 (0.70 to 1.25) | 0.92 (0.68 to 1.23) | ||
| Less than 9 years | 35 | 67468 | 0.93 (0.66 to 1.32) | 0.91 (0.64 to 1.30) | ||
| 10 or more years | 17 | 29202 | 0.99 (0.61 to 1.60) | 0.95 (0.58 to 1.56) | ||
| Combined ever powder use§ | ||||||
| Never | 197 | 361583 | 1.0 (referent) | .67 | 1.0 (referent) | .77 |
| Ever‡ | 232 | 404983 | 1.07 (0.89 to 1.30) | 1.06 (0.87 to 1.28) | ||
| Less than 9 years | 135 | 228931 | 1.12 (0.90 to 1.39) | 1.09 (0.88 to 1.36) | ||
| 10 or more years | 97 | 173307 | 1.03 (0.81 to 1.31) | 1.02 (0.80 to 1.30) | ||
* Adjusted for: Age (continuous), race (white, nonwhite, missing), oral contraceptive duration in years (never, <5, 5 to <10, 10 to <15, 15+, missing), hormone replacement therapy duration in years (never, <5, 5 to <10, 10 to <15, 15+, missing), family history (yes, no, missing), age (y) at last birth (never, <20, 20 to <30, 30+, missing), body mass index in kg/m2 (<25.0, 25.0 to <30.0, 30.0+, missing), smoking (never, past, current, missing), tubal ligation (yes, no, missing), and parity (0, 1 to 2, 3 to 4, 5+, children, missing).
† Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated in cox proportional hazard regression models; P trend was estimated by modeling categories as continuous. All statistical tests were two-sided.
‡ Person-years may not add up; duration information was missing for some.
§ Combined ever powder use is the longest duration of use among the applications to genitals, sanitary napkins, and diaphragms.