Association of Diet, Supplements, and Physical Activity With Risk of Incident Spondyloarthritis

Background/Objective: Dietary, supplement, and activity exposures have only been studied in spondyloarthritis (SpA) with retrospective studies. We aimed to determine the association of diet, supplements, and physical activity with incident SpA. Patients and Methods: We performed a case-control study in the Mayo Clinic Biobank from 2009 through 2015, matching criteria-confirmed incident SpA cases to controls 1:5 on age, sex, recruitment year, and location. Questionnaires assessed 16 dietary, 29 supplement, and leisure-time/work activity exposures. Logistic regression models calculated adjusted odds ratios (aOR) with 95% CIs of SpA for each exposure, adjusting for covariates. Sensitivity analyses were conducted within HLA-B27-positive patients, and those with baseline questionnaires completed 5+ years before index. Results: We identified 73 cases of incident SpA matched with 365 controls (mean age: 60, 70% females). No dietary or activity exposures were associated with SpA overall. However, among HLA-B27-positive individuals, non-diet soft drink consumption was associated with increased risk of SpA (aOR: 4.82, 95% CI: 1.29-18.1), whereas caffeinated coffee was associated with decreased risk (aOR: 0.20, 95% CI: 0.04-0.89). Zinc was associated with increased risk of SpA (aOR: 4.16, 95% CI: 1.19-14.6), as were B vitamins in the HLA-B27-positive subgroup (aOR: 4.21, 95% CI: 1.04-17.1). In the 5-year sensitivity analysis, low leisure-time physical activity plus high work physical activity was associated with increased risk of SpA (relative excess risk due to interaction: 0.50, 95% CI: 0.03-0.98). Conclusions: Due to small sample size and multiple comparisons, the risk factors we identified (non-diet soft drinks, B vitamins, and zinc) should be considered hypothesis-generating and warrant further investigation.