Risk of any infection according to levels of plasma iron, transferrin saturation, and ferritin. Solid red lines are hazard ratios obtained using Cox regression, broken black lines indicate 95% CIs. Analyses were multivariable adjusted for age, year of birth, sex, smoking status, cumulative smoking in pack-years, alcohol consumption, body mass index, menopausal status, study cohort, Charlson comorbidity index, and level of C-reactive protein. Reference for the continuous models (splines) is the median value of plasma iron (14 μmol/L), transferrin saturation (23%), or ferritin (100 μg/L) in the respective analyses. Total number of individuals in the analyses on risk of any infection according to iron, transferrin saturation, and ferritin were 136 656, 136 599, and 38 020, respectively. All individuals who had a measurement of iron, transferrin saturation, or ferritin were included in the categorical analyses and in modeling of the splines, but when drawing the spline curves the x-axis was capped at the 99.9th percentile. ∗Hazard ratio, 95% CI, and P value obtained using Cox regression.^†Subhazard ratio and 95% CI obtained using Fine-Gray competing risk regression on risk of any infection with death from any cause as competing risk. ref., reference group; sat., saturation.