TABLE II.
RATE RATIOS (RR) AND 95% CONFIDENCE INTERVALS (CIs) FOR LAPAROSCOPICALLY-CONFIRMED ENDOMETRIOSIS (N=1383) ACCORDING TO QUINTILE OF CUMULATIVE AVERAGED MICRONUTRIENT INTAKE FROM ALL SOURCES (FOODS AND SUPPLEMENTS) AMONG WOMEN IN THE NURSES’ HEALTH STUDY II, 1991–2007
| Quintile of Intake
|
||||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | P-value* | |
| Thiamine (B1) | ||||||
| Median intake, mg | 1.3 | 1.6 | 2.0 | 2.9 | 8.1 | |
| Number of cases | 288 | 255 | 278 | 274 | 287 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.85 (0.72, 1.01) | 0.91 (0.77, 1.08) | 0.89 (0.75, 1.05) | 1.01 (0.85, 1.19) | 0.21 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.89 (0.75, 1.05) | 0.95 (0.80, 1.13) | 0.92 (0.78,1.09) | 0.99 (0.84, 1.17) | 0.51 |
| Niacin (B3) | ||||||
| Median intake, mg | 20.2 | 24.7 | 29.7 | 38.1 | 59.1 | |
| Number of cases | 283 | 256 | 253 | 279 | 311 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.88 (0.74, 1.05) | 0.87 (0.73, 1.03) | 0.95 (0.81, 1.13) | 1.17 (1.00, 1.38) | 0.002 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.91 (0.76, 1.07) | 0.88 (0.74, 1.05) | 0.96 (0.81, 1.14) | 1.11 (0.94, 1.30) | 0.03 |
| Pyridoxine (B6) | ||||||
| Median intake, mg | 1.7 | 2.2 | 2.8 | 4.1 | 15.6 | |
| Number of cases | 270 | 267 | 279 | 294 | 272 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.91 (0.77, 1.08) | 0.95 (0.80, 1.13) | 1.05 (0.89, 1.24) | 0.96 (0.81, 1.14) | 0.90 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.91 (0.77, 1.08) | 0.94 (0.79, 1.11) | 1.03 (0.87, 1.21) | 0.93 (0.79, 1.10) | 0.66 |
| Folate (B9) | ||||||
| Median intake, mcg | 239.0 | 319.0 | 416.2 | 575.0 | 819.4 | |
| Number of cases | 277 | 277 | 288 | 266 | 274 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.96 (0.81, 1.13) | 1.00 (0.85, 1.18) | 0.93 (0.78, 1.10) | 0.92 (0.78, 1.09) | 0.26 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.95 (0.81, 1.13) | 0.97 (0.82, 1.15) | 0.88 (0.74, 1.04) | 0.91 (0.77, 1.08) | 0.19 |
| Cobalamine (B12) | ||||||
| Median intake, mcg | 4.0 | 6.0 | 8.0 | 11.0 | 18.5 | |
| Number of cases | 244 | 319 | 258 | 292 | 269 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 1.11 (0.94, 1.31) | 1.09 (0.92, 1.30) | 1.14 (0.96, 1.35) | 1.10 (0.92, 1.30) | 0.51 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 1.13 (0.95, 1.33) | 1.10 (0.92, 1.31) | 1.13 (0.95, 1.34) | 1.08 (0.91, 1.28) | 0.71 |
| Vitamin C | ||||||
| Median intake, mg | 84.0 | 127.0 | 172.2 | 250.5 | 604.0 | |
| Number of cases | 294 | 257 | 275 | 250 | 306 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.87 (0.74, 1.03) | 0.92 (0.78, 1.09) | 0.86 (0.73, 1.02) | 1.13 (0.96, 1.33) | 0.007 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.88 (0.74, 1.04) | 0.92 (0.78, 1.09) | 0.85 (0.71, 1.00) | 1.02 (0.87, 1.20) | 0.26 |
| Vitamin E | ||||||
| Median intake, mg | 5.1 | 6.8 | 12.2 | 25.3 | 153.0 | |
| Number of cases | 285 | 274 | 261 | 258 | 304 | |
| Age-adjusted RR (95% CI) | 1.00 (referent) | 0.96 (0.81, 1.13) | 0.89 (0.75, 1.06) | 0.90 (0.76, 1.07) | 1.17 (0.99, 1.38) | 0.005 |
| Multivariable RR (95% CI)+ | 1.00 (referent) | 0.93 (0.78, 1.09) | 0.85 (0.72, 1.01) | 0.86 (0.73, 1.02) | 1.05 (0.89, 1.23) | 0.05 |
P-value, test for linear trend calculated with median intake of the micronutrient in each quintile as a continuous variable.
Multivariable model was stratified by age in months at start of follow-up and calendar year of the current questionnaire cycle and was simultaneously adjusted for age at menarche (<10, 10, 11, 12, 13, 14, 15, 16, >16 years), length of menstrual cycle (<26, 26–31, 32–50, 51+ days), parity (nulliparous, 1, 2, 3, 4+ pregnancies lasting >6 months), body mass index (<19, 19–20.4, 20.5–21.9, 22–24.9, 25–29.9, 30+ kg/m2), race (Caucasian vs. women of color), and total energy (continuous).
CI, confidence interval; RR, rate ratio.