Lifestyle Factors and Disease Activity Over Time in Early Axial Spondyloarthritis: The SPondyloArthritis Caught Early (SPACE) Cohort.

Objective: Our aim was to study the importance of baseline BMI, smoking, and alcohol consumption (AC) for disease activity (DA) over 1 year in early axial spondyloarthritis (axSpA), stratified by sex.

Methods: In the SPondyloArthritis Caught Early cohort (patients with chronic back pain onset at age < 45 yrs, with pain for ≥ 3 months and ≤ 2 yrs), the Ankylosing Spondylitis Disease Activity Score (ASDAS) was recorded at inclusion, 3, and 12 months. All patients included in the analysis had axSpA based on a high physician's level of confidence at baseline. Differences in ASDAS over 1 year by BMI (normal < 25 kg/m, overweight 25-29.9 kg/m, and obese ≥ 30 kg/m), smoking history (never/previous/current), and AC (none, 0.1-2 units/week, 3-5 units/week, and ≥ 6 units/week) at baseline were estimated using mixed linear regression models.

Results: There were 344 subjects (mean age of 30.3 yrs; 49.4% men). In women, obesity was associated with 0.60 (95% CI 0.28-0.91) higher ASDAS compared to normal BMI. In both sexes, AC tended to be associated with lower DA over 1 year, with a significant association only in women with the highest AC (mean difference of -0.55, 95% CI -1.05 to -0.04). Smoking was associated with higher ASDAS over 1 year compared to never smoking in both sexes, although the difference reached statistical significance only in female former smokers. Results were similar in multivariable analysis, adjusted for all lifestyle factors and other confounders.

Conclusion: In early axSpA, BMI and smoking are associated with higher DA over 1 year, and AC with lower DA. The magnitude of the modest associations may differ between men and women.