Table 1.
Baseline characteristics of study participants stratified by red blood cell docosahexaenoic acid and eicosapentaenoic acid (RBC DHA+EPA) content (N = 6706).
| Characteristic | RBC DHA+EPA Tertile
|
P value | |||
|---|---|---|---|---|---|
| Total (N=6706) | Lowest (RBC content: 2.0–4.5%; N=2235) | Middle (RBC content: 4.5–5.6%; N=2236) | Highest (RBC content: 5.6–15.6%; N=2235) | ||
| Hormone therapy (HT) trial | <.001 | ||||
| Estrogen alone | 2630 (39.2) | 919 (41.1) | 907 (40.6) | 804 (36.0) | |
| Estrogen + progestin | 4076 (60.8) | 1316 (58.9) | 1329 (59.4) | 1431 (64.0) | |
| HT trial treatment assignment | 0.151 | ||||
| Active treatment | 3315 (49.4) | 1100 (49.2) | 1140 (51.0) | 1075 (48.1) | |
| Placebo | 3391 (50.6) | 1135 (50.8) | 1096 (49.0) | 1160 (51.9) | |
| Age in years at enrollment | <.001 | ||||
| Median (min–max) | 70 (63–81) | 69 (63–81) | 70 (64–79) | 70 (63–79) | |
| Baseline 3MS score | 0.575 | ||||
| Median (min–max) | 96 (66–100) | 96 (68–100) | 96 (68–100) | 96 (66–100) | |
| APOE genotype | 0.160 | ||||
| No ε4 alleles | 3984 (59.4) | 1353 (60.5) | 1384 (61.9) | 1247 (55.8) | |
| 1+ ε4 alleles | 1349 (20.1) | 496 (22.2) | 442 (19.8) | 411 (18.4) | |
| Unavailable | 1373 (20.5) | 386 (17.3) | 410 (18.3) | 577 (25.8) | |
| Education | <.001 | ||||
| College or postgraduate degree | 2014 (30.0) | 495 (22.1) | 632 (28.3) | 887 (39.7) | |
| Some post-secondary education | 2715 (40.5) | 948 (42.4) | 926 (41.4) | 841 (37.6) | |
| High school or less | 1977 (29.5) | 792 (35.4) | 678 (30.3) | 507 (22.7) | |
| Race/ethnicity | <.001 | ||||
| Black | 456 (6.8) | 61 (2.7) | 145 (6.5) | 250 (11.2) | |
| White | 5867 (87.5) | 2058 (92.1) | 1998 (89.4) | 1811 (81.0) | |
| Other | 383 (5.7) | 116 (5.2) | 93 (4.2) | 174 (7.8) | |
| Health conditions and behaviors | |||||
| Cardiovascular disease | 1344 (20.0) | 443 (19.8) | 452 (20.2) | 449 (20.1) | 0.945 |
| Hypertension | 3581 (53.4) | 1208 (54.0) | 1195 (53.4) | 1178 (52.7) | 0.666 |
| Diabetes | 744 (11.1) | 255 (11.4) | 267 (11.9) | 222 (9.9) | 0.086 |
| Current smoker | 459 (6.8) | 214 (9.6) | 127 (5.7) | 118 (5.3) | <.001 |
| Past alcohol user | 1314 (19.6) | 499 (22.3) | 444 (19.9) | 371 (16.6) | <.001 |
| Body-mass Index (BMI), kg/m2 | <.001 | ||||
| Median (min–max) | 27.6 (13.8–66.7) | 28.0 (13.8–66.7) | 27.9 (17.0–64.9) | 26.9 (15.0–66.1) | |
| Alcohol servings per week | <.001 | ||||
| Median (min–max) | 0.2 (0.0–64.7) | 0.0 (0.0–49.2) | 0.4 (0.0–64.2) | 0.4 (0.0–64.7) | |
Participants were ranked and divided into DHA+EPA tertiles based on the mean of the 10 imputed RBC DHA+EPA values. Summary statistics are the group median (range) for continuous variables or category count (%) for categorical variables. P values for between-group differences across tertiles are based on Kruskal-Wallis and chi-square test results for continuous and categorical variables, respectively. Participants with missing APOE genotype data were excluded from chi-square test for differences in APOE genotype across tertiles. For simplicity, the 11 educational attainment levels self-reported by WHIMS participants were categorized as follows: a doctoral degree, master’s degree, some post-graduate or professional education, and college graduate as “college or postgraduate degree”; some college or associate’s degree, and vocational or training school as “some post-secondary education”; and high school diploma or GED, some high school, and grade school as “high school or less.”