| Known factors that can contribute to SLE | Frequency | Percentage |
| Pregnancy | 133 | 69.3% |
| Exposition to sun | 117 | 60.9% |
| Drugs | 112 | 58.3% |
| Stress | 110 | 57.3% |
| Tobacco | 96 | 50.0% |
| Infections | 72 | 37.5% |
| Contact with allergen | 48 | 25.0% |
| Alcohol | 11 | 5.7% |
| Don’t know | 8 | 4.2% |