Table 1.

Baseline demographics among BMI groups of White women in the WHI observational study

CovariateNormal (18.5–24.9 kg/m2)Overweight (25–29.9 kg/m2)Obese (30+ kg/m2)Total
BMI (n, %)26,396 (42.8)21,208 (34.4)14,053 (22.8)61,657 (100)
Age group at baseline (n, %)P < 0.0001
 50–598,845 (33.5)6,150 (29.0)4,471 (31.8)19,466
 60–6911,477 (43.5)9,724 (45.9)6,625 (47.1)27,826
 70–79+6,074 (23.0)5,334 (25.1)2,957 (21.1)14,365
Education (n, %)P < 0.0001
 Less than high school diploma or GED6,141 (23.2)6,145 (29.0)5,072 (36.1)17,358
 Some school after high school diploma6,807 (25.8)5,936 (28.0)4,089 (29.1)16,832
 College degree or higher13,448 (51.0)9,127 (43.0)4,892 (34.8)27,467
Times walked outsideP < 0.0001
 Never2,884 (10.9)2,858 (13.5)3,009 (21.4)8,751
 1–3×/mo3,137 (11.9)2,969 (14.0)2,535 (18.0)8,641
 1–3×/wk10,082 (38.2)8,452 (39.8)5,404 (38.5)23,938
 4–7+/wk10,293 (39.0)6,929 (32.7)3,105 (22.1)20,327
Geographic sun exposure (Langleys)P < 0.0001
 300–3257,887 (29.9)7,007 (33.0)4,944 (35.2)19,838
 3505,154 (19.5)4,612 (21.7)3,313 (23.6)13,079
 375–3803,399 (12.9)2,203 (10.4)1,333 (9.5)6,935
 400–4304,427 (16.7)3,344 (15.8)2,037 (14.5)9,808
 475–5005,529 (21.0)4,042 (19.1)2,426 (17.2)11,997
NMSC at baselineP < 0.0001
 No23,665 (89.7)19,333 (91.2)12,979 (92.4)55,977
 Yes2,731 (10.3)1,875 (8.8)1,074 (7.6)5,680
Melanoma at baselineP = 0.021
 No26,120 (99.0)20,934 (98.7)13,872 (98.7)60,926
 Yes276 (1.0)274 (1.3)181 (1.3)731
Smoking statusP < 0.0001
 Never smoked13,326 (50.5)10,520 (49.6)6,996 (49.8)30,842
 Past smoker11,431 (43.3)9,605 (45.3)6,451 (45.9)27,487
 Current smoker1,639 (6.2)1,083 (5.1)606 (4.3)3,328
Hormone therapy useP < 0.0001
 Never used8,769 (33.2)8,020 (37.8)6,329 (45.1)23,118
 Past user3,713 (14.1)3,205 (15.1)2,126 (15.1)9,044
 Current user13,914 (52.7)9,983 (47.1)5,598 (39.8)29,495
Skin reaction to the sunP < 0.0001
 Does not burn9,601 (36.4)7,654 (36.1)4,753 (33.8)22,008
 Burns and then tans14,212 (53.8)11,004 (51.9)7,310 (52.0)32,526
 Burns and does not tan2,583 (9.8)2,550 (12.0)1,990 (14.2)7,123
Time spent outdoors in summer as a childP < 0.0001
 Less than 30 minutes609 (2.3)440 (2.1)322 (2.3)1,371
 30 minutes to 2 hours7,282 (27.6)5,419 (25.6)3,194 (22.7)15,895
 More than 2 hours18,505 (70.2)15,349 (72.4)10,537 (75.0)44,391
Time spent outdoors in summer nowP < 0.0001
 Less than 30 minutes7,063 (26.7)6,359 (30.0)5,336 (38.0)18,758
 30 minutes to 2 hours13,705 (51.9)10,705 (50.5)6,532 (46.5)30,942
 More than 2 hours5,628 (21.4)4,144 (19.5)2,185 (15.5)11,957
Usually use sunscreen outsideP < 0.0001
 No10,841 (41.1)9,953 (46.9)7,765 (55.3)28,559
 Yes15,555 (58.9)11,255 (53.1)6,288 (44.7)33,098

NOTE: Only those participants who were in the observational study of the WHI, reported their ethnicity as White, and were not missing any variables in the scientific model were included (there were 78,016 White women who were eligible). Outcomes are recorded from the start of the study period and participants are censored at death, last study visit, or 10 years from the start of the study period, whichever came first. Outcome events are recorded through August 2006.