Association between sun-protective behaviours and psoriasis, stratified by age, gender, race or ethnicity and smoking status
| Subgroup | Frequency | Staying in the shade | Wearing long sleeves | Using sunscreen | Overall sun protection |
| OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | ||
| Overall | |||||
| Unadjusted | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.99 (0.66 to 1.50) | 0.55 (0.34 to 0.89)* | 1.47 (0.98 to 2.20) | 0.93 (0.65 to 1.32) | |
| Frequent | 1.33 (0.88 to 2.02) | 1.26 (0.77 to 2.03) | 1.22 (0.84 to 1.76) | 1.91 (1.08 to 3.39)* | |
| Adjusted | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.95 (0.62 to 1.45) | 0.55 (0.33 to 0.90)* | 1.25 (0.82 to 1.91) | 0.90 (0.62 to 1.31) | |
| Frequent | 1.42 (0.92 to 2.18) | 1.36 (0.82 to 2.26) | 0.96 (0.62 to 1.50) | 1.67 (0.90 to 3.12) | |
| Age (years) | |||||
| 20–39 | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.71 (0.40 to 1.25) | 0.42 (0.18 to 0.98)* | 1.21 (0.66 to 2.19) | 0.91 (0.53 to 1.55) | |
| Frequent | 1.14 (0.61 to 2.13) | 0.86 (0.31 to 2.42) | 1.23 (0.66 to 2.29) | 1.27 (0.41 to 3.93) | |
| 40–59 | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 1.24 (0.67 to 2.27) | 0.64 (0.34 to 1.20) | 1.28 (0.73 to 2.27) | 0.92 (0.55 to 1.53) | |
| Frequent | 1.77 (0.96 to 3.24) | 1.75 (0.97 to 3.16) | 0.84 (0.46 to 1.53) | 1.97 (0.92 to 4.20) | |
| Gender | |||||
| Female | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.63 (0.35 to 1.16) | 0.56 (0.28 to 1.12) | 0.88 (0.48 to 1.59) | 0.58 (0.35 to 0.97)* | |
| Frequent | 1.33 (0.74 to 2.39) | 1.37 (0.62 to 3.03) | 0.56 (0.31 to 1.02) | 1.23 (0.55 to 2.76) | |
| Male | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 1.28 (0.72 to 2.29) | 0.53 (0.26 to 1.07) | 1.71 (0.95 to 3.09) | 1.32 (0.78 to 2.23) | |
| Frequent | 1.40 (0.74 to 2.64) | 1.30 (0.68 to 2.48) | 1.75 (0.97 to 3.15) | 1.95 (0.74 to 5.11) | |
| Race or ethnicity | |||||
| Non-Hispanic white | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.93 (0.56 to 1.55) | 0.52 (0.28 to 0.97)* | 1.28 (0.78 to 2.11) | 0.80 (0.50 to 1.26) | |
| Frequent | 1.69 (1.00 to 2.84)* | 1.43 (0.71 to 2.86) | 0.83 (0.48 to 1.43) | 1.73 (0.82 to 3.66) | |
| Other | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 1.14 (0.64 to 2.03) | 0.68 (0.37 to 1.22) | 1.10 (0.59 to 2.06) | 1.39 (0.83 to 2.32) | |
| Frequent | 0.92 (0.52 to 1.61) | 1.20 (0.68 to 2.12) | 1.94 (1.09 to 3.44)* | 1.66 (0.72 to 3.82) | |
| Smoking status | |||||
| Non-smokers | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 0.76 (0.42 to 1.35) | 0.49 (0.25 to 0.95)* | 1.71 (0.93 to 3.14) | 0.74 (0.43 to 1.26) | |
| Frequent | 1.00 (0.55 to 1.82) | 0.42 (0.19 to 0.93)* | 1.14 (0.58 to 2.21) | 0.87 (0.36 to 2.09) | |
| Smokers† | Rare | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Moderate | 1.20 (0.66 to 2.20) | 0.62 (0.31 to 1.25) | 1.00 (0.53 to 1.89) | 1.12 (0.67 to 1.85) | |
| Frequent | 2.05 (1.11 to 3.78)* | 3.02 (1.57 to 5.79)** | 0.91 (0.49 to 1.70) | 3.28 (1.41 to 7.63)** |
Each stratification was adjusted for age, gender, race or ethnicity, country of birth, education level, marital status, body mass index, smoking and alcohol drinking status, sun sensitivity, and time spent outdoors except the stratification factor itself. All ORs and 95% CIs are based on data weighted to represent the US population.
Boldface indicates statistical significance.
*P<0.05, **P<0.01.
†Smokers refer to current smokers and former smokers.