Characteristics of participants with and without psoriasis
| Characteristic | Participants | P value | ||
| Total (N=9735) | Without psoriasis (n=9480) | With psoriasis (n=255) | ||
| Age (years), mean±SD (95% CI) | 39.6±11.7 (39.3 to 39.9) | 39.5±11.7 (39.2 to 39.8) | 42.7±11.3 (40.9 to 44.5) | <0.001 |
| Gender | ||||
| Female | 4882 (49.7) (48.4 to 50.9) | 4750 (49.7) (48.4 to 50.9) | 132 (50.0) (42.2 to 57.8) | 0.91 |
| Male | 4853 (50.3) (49.1 to 51.6) | 4730 (50.3) (49.1 to 51.6) | 123 (50.0) (42.2 to 57.8) | |
| Race or ethnicity | ||||
| Non-Hispanic white | 4030 (64.5) (63.5 to 65.6) | 3883 (64.2) (63.1 to 65.2) | 147 (77.4) (72.0 to 82.0) | <0.001 |
| Non-Hispanic black | 2048 (11.9) (11.3 to 12.4) | 2021 (12.0) (11.5 to 12.6) | 27 (5.4) (3.6 to 8.0) | |
| Hispanic | 938 (6.2) (5.8 to 6.6) | 915 (6.2) (5.8 to 6.7) | 23 (5.3) (3.4 to 8.2) | |
| Other* | 2719 (17.4) (16.7 to 18.2) | 2661 (17.6) (16.8 to 18.4) | 58 (11.9) (8.7 to 16.1) | |
| Education level | ||||
| <9th grade | 645 (4.0) (3.6 to 4.4) | 631 (4.0) (3.7 to 4.4) | 14 (2.3) (1.3 to 4.1) | 0.06 |
| 9th–11th grade | 1363 (10.9) (10.2 to 11.6) | 1336 (11.0) (10.3 to 11.7) | 27 (6.7) (4.3 to 10.5) | |
| High school graduate/GED or equivalent | 2137 (21.1) (20.1 to 22.1) | 2080 (21.1) (20.1 to 22.1) | 57 (21.5) (15.8 to 28.6) | |
| Some college or AA degree | 3115 (33.1) (31.9 to 34.3) | 3035 (33.1) (31.9 to 34.3) | 80 (33.0) (26.0 to 40.9) | |
| College graduate or above | 2475 (31.0) (29.8 to 32.2) | 2398 (30.8) (29.6 to 32.1) | 77 (36.4) (29.1 to 44.4) | |
| Country of birth | ||||
| Not USA-born | 2793 (18.5) (17.7 to 19.3) | 2745 (18.7) (17.9 to 19.5) | 48 (9.9) (7.1 to 13.6) | <0.001 |
| USA-born | 6942 (81.5) (80.7 to 82.3) | 6735 (81.3) (80.5 to 82.1) | 207 (90.1) (86.4 to 92.9) | |
| Marital status | ||||
| Never married | 2563 (24.1) (23.1 to 25.2) | 2507 (24.2) (23.1 to 25.2) | 56 (22.9) (17.0 to 30.1) | 0.64 |
| Married or living with partner | 5719 (62.1) (60.8 to 63.3) | 5571 (62.1) (60.9 to 63.3) | 148 (61.4) (53.6 to 68.7) | |
| Widowed or divorced or separated | 1453 (13.8) (13.0 to 14.7) | 1402 (13.8) (12.9 to 14.7) | 51 (15.7) (10.9 to 22) | |
| BMI (kg/m2) | ||||
| <25 | 3043 (31.4) (30.2 to 32.6) | 2977 (31.5) (30.4 to 32.7) | 66 (26.2) (20.0 to 33.5) | 0.17 |
| ≥25–<30 | 3071 (32.8) (31.6 to 34.0) | 2991 (32.7) (31.5 to 34.0) | 80 (35.4) (28.1 to 43.4) | |
| ≥30 | 3621 (35.8) (34.6 to 37.0) | 3512 (35.7) (34.5 to 37.0) | 109 (38.5) (31.3 to 46.2) | |
| Alcohol drinkers | ||||
| No | 2279 (18.6) (17.7 to 19.5) | 2226 (18.6) (17.7 to 19.5) | 53 (17.7) (12.8 to 23.9) | 0.70 |
| Yes | 7456 (81.4) (80.5 to 82.3) | 7254 (81.4) (80.5 to 82.3) | 202 (82.3) (76.1 to 87.2) | |
| Smoking status | ||||
| Non-smokers | 5670 (57.8) (56.6 to 59.1) | 5547 (58.1) (56.8 to 59.3) | 123 (49.2) (41.4 to 57.0) | <0.001 |
| Former smokers | 1647 (19.2) (18.2 to 20.3) | 1587 (18.9) (17.9 to 20.0) | 60 (30.1) (23.0 to 38.2) | |
| Current smokers | 2418 (22.9) (21.9 to 24.0) | 2346 (23.0) (22.0 to 24.1) | 72 (20.8) (15.7 to 27.0) | |
| Sun sensitivity† | ||||
| None | 956 (12.7) (11.9 to 13.7) | 923 (12.7) (11.8 to 13.6) | 33 (15.4) (10.3 to 22.4) | 0.006 |
| Mild | 4667 (52.1) (50.8 to 53.3) | 4524 (51.9) (50.6 to 53.2) | 143 (58.4) (50.6 to 65.9) | |
| Severe | 4112 (35.2) (34.0 to 36.3) | 4033 (35.4) (34.3 to 6.6) | 79 (26.2) (20.1 to 33.3) | |
| Time spent outdoors‡ (minutes per day) | ||||
| <60 | 3891 (38.8) (37.6 to 40.1) | 3790 (38.9) (37.7 to 40.2) | 101 (35.2) (28.1 to 42.9) | 0.21 |
| ≥60 | 5844 (61.2) (59.9 to 62.4) | 5690 (61.1) (59.8 to 62.3) | 154 (64.8) (57.1 to 71.9) | |
| Staying in the shade | ||||
| Rare | 2546 (27.2) (26.0 to 28.3) | 2489 (27.2) (26.1 to 28.4) | 57 (24.8) (18.6 to 32.2) | 0.07 |
| Moderate | 3776 (41.9) (40.6 to 43.1) | 3677 (42.0) (40.7 to 43.3) | 99 (37.9) (30.7 to 45.7) | |
| Frequent | 3413 (31.0) (29.8 to 32.1) | 3314 (30.8) (29.6 to 31.9) | 99 (37.3) (30.0 to 45.2) | |
| Wearing long sleeves | ||||
| Rare | 6742 (70.9) (69.8 to 72.1) | 6557 (70.8) (69.6 to 71.9) | 185 (76.0) (68.8 to 81.9) | 0.002 |
| Moderate | 1941 (20.1) (19.1 to 21.1) | 1907 (20.3) (19.3 to 21.4) | 34 (12.0) (7.9 to 17.9) | |
| Frequent | 1052 (9.0) (8.3 to 9.7) | 1016 (8.9) (8.2 to 9.6) | 36 (12.0) (7.9 to 17.9) | |
| Using sunscreen | ||||
| Rare | 5579 (48.5) (47.2 to 49.7) | 5449 (48.7) (47.4 to 50.0) | 130 (41.8) (34.5 to 49.5) | 0.04 |
| Moderate | 1819 (21.8) (20.7 to 22.9) | 1763 (21.6) (20.5 to 22.7) | 56 (27.2) (20.5 to 35.2) | |
| Frequent | 2337 (29.8) (28.6 to 31.0) | 2268 (29.7) (28.5 to 31.0) | 69 (31.0) (24.2 to 38.8) | |
| Overall sun protection§ | ||||
| Rare | 3249 (31.9) (30.8 to 33.1) | 3174 (31.9) (30.8 to 33.1) | 75 (31.4) (24.5 to 39.1) | <0.001 |
| Moderate | 5850 (61.3) (60.0 to 62.5) | 5698 (61.4) (60.2 to 62.6) | 152 (56.1) (48.2 to 63.7) | |
| Frequent | 636 (6.8) (6.2 to 7.5) | 608 (6.7) (6.0 to 7.4) | 28 (12.5) (7.9 to 19.3) | |
Data are presented as unweighted number (weighted percentage) (95% CI) unless otherwise indicated.
Boldface indicates statistical significance.
BMI is calculated as weight in kilograms divided by height in metres squared.
*Included Mexican American and multiracial participants.
†Sun sensitivity was determined by the answer to the skin reaction to the sun without sunscreen or protective clothing for half an hour: none (‘nothing would happen in half an hour’), mild (‘mildly burned with some tanning’ or ‘turning darker without a sunburn’) and severe (‘get a severe sunburn with blisters’ or ‘a severe sunburn for a few days with peeling’).
‡Time spent outdoors refers to the average minutes spent outdoors from 09:00 to 17:00 on each day of the week considering that there are 5 working days and 2 non-working days in a week.
§Overall sun protection reflects the general condition of sun protection, including staying in the shade, wearing long sleeves and using sunscreen.
AA, associate degree; BMI, body mass index; GED, general equivalency diploma.