While the association between individual factors related to lifestyle and the risk of SLE has been previously evaluated, it is unclear how the combination of these factors might affect the risk of incident SLE. We prospectively evaluated whether a combination of healthy lifestyle factors is associated with lower risk of incident SLE and its subtypes (dsDNA positive and negative).
We included 185,962 women with 203 incident SLE cases (96 anti-dsDNA positive,107 anti-dsDNA negative) during 4,649,477 person-years of follow-up from the Nurses' Health Study (NHS) and NHSII cohorts. The Healthy Lifestyle Index Score (HLIS) was calculated at baseline and approximately every 2 years in follow-up using five factors: alcohol consumption, body mass index, smoking, diet, and exercise. A time-varying Cox hazards regression model estimated the adjusted hazard ratios (HR) for SLE risk. The partial population attributable risk (PAR%) of SLE development was calculated.
A higher HLIS was associated with a lower risk of SLE overall (HR 0.81 [95%CI 0.71-0.94]) and dsDNA positive SLE (HR 0.78 [95%CI 0.63-0.95]). Women with four or more healthy factors had the lowest SLE risk overall (HR 0.42 [95%CI 0.25-0.70]) and dsDNA positive SLE (HR 0.35 [95%CI 0.17-0.75]) compared to women with less than or equal to one healthy behavior. The PAR% for SLE from adhering to four or more healthy behaviors was 47.7% [95%CI 23.1-66.6].
Nearly half of SLE risk, a disease where significant evidence of genetic involvement has been established, might be reduced with adherence to modifiable healthy lifestyle behaviors.