Blood cadmium is associated with increased fracture risk in never-smokers - results from a case-control study using data from the Malmö Diet and Cancer cohort.

Abstract

Several studies have shown associations between cadmium (Cd) exposure and an increased risk of fractures. However, the size of the risk is still unclear and proper adjustment for smoking is a challenge. The aim of this study was to quantify the association between dietary cadmium measured in blood and fracture risk in the general Swedish population through a large population-based case-control study in never-smokers. The study included 2113 incident cases with osteoporosis-related fractures and the same number of age- and sex-matched controls in never-smokers from the Swedish population-based Malmö Diet and Cancer study cohort. Cd in blood (B-Cd) was analyzed at baseline (1991-1996). Incident osteoporosis-related fractures (of the hip, distal radius, and proximal humerus) up to the year 2014 were identified using the National Patient Register. Associations between B-Cd and fractures were analyzed using logistic regression. Median B-Cd was 0.22 μg/L (P25 = 0.16, P75 = 0.31) among 2103 cases and 0.21 (P25 = 0.15, P75 = 0.30) among 2105 controls. The risk of fracture was significantly increased (OR 1.58; 95 % confidence interval 1.08-2.31, per μg/L of B-Cd), after adjustment for age, sex, BMI, physical activity, and fiber consumption. In analyses by cadmium quartiles, the OR increased monotonically and was significant in the highest quartile of B-Cd (for B-Cd > 0.31 versus B-Cd < 0.15 μg/L; OR 1.21; 95 % confidence interval 1.01-1.45). Even modestly increased blood cadmium in never-smokers is associated with increased risk of incident osteoporosis-related fractures.