Association of iron status with the risk of bloodstream infections: results from the prospective population-based HUNT Study in Norway

PURPOSE: As iron is essential for both immune function and microbial growth, alterations in iron status could influence the risk of infections. We assessed the associations of iron status with risk of bloodstream infections (BSIs) and BSI mortality. METHODS: We measured serum iron, transferrin saturation (Tsat) and total iron-binding capacity (TIBC) in 61,852 participants in the population-based HUNT2 study (1995-97). Incident BSIs (1995-2011) were identified through linkage with the Mid-Norway Sepsis Register, which includes prospectively registered information on BSI from local and regional hospitals. We assessed the risk of a first-time BSI and BSI mortality with the iron indices using Cox proportional hazards regression analysis. RESULTS: During a median follow-up of 14.8 years, 1738 individuals experienced at least one episode of BSI, and 370 died within 30 days after a BSI. In age- and sex-adjusted analyses, BSI risk was increased among participants with indices of iron deficiency, serum iron ≤ 2.5th percentile (HR 1.72, 95% CI 1.34-2.21), Tsat ≤ 2.5th percentile (HR 1.48, 95% CI 1.12-1.96) or TIBC ≥ 97.5th percentile (HR 1.46, 95% CI 1.06-2.01). The associations remained similar after adjusting for comorbidities and exclusion of BSI related to cancer, rheumatic illnesses and inflammatory bowel disease. BSI mortality showed similar associations. CONCLUSION: Indices of severe iron deficiency are associated with an increased risk of a future BSI.