U-shaped relationship between vitamin D levels and long-term outcome in large cohort of survivors of acute myocardial infarction

BACKGROUND: Previous studies in the setting of patients with acute myocardial infarction (AMI) have demonstrated that hypovitaminosis D is associated with increased mortality risk during a follow-up whose median did not exceed two years. OBJECTIVE: To evaluate the impact of vitamin D levels on long-term mortality in patients with AMI. RESULTS: In our study 477 patients with AMI were included. During a median follow-up period of 57 (IQR 53-64) months, 93 patients (20%) died. A non-linear U-shaped relationship between 25(OH)D levels and long-term mortality was observed; patients with vitamin D<10ng/mL and >30ng/mL had higher mortality rate than those with intermediate values. After adjustment for differences in baseline features and treatment, it was confirmed that extreme values of vitamin D (<10 or >30ng/mL) are independent predictors of mortality with HR of 3.02 (95% CI 1.78-5.11). Other independent predictors of outcome were age, NYHA class at discharge, treatment with ACE inhibitors and statins. The estimated time-dependent ROC curve of the multivariable model including vitamin D showed an AUC significantly higher than the model without vitamin D: AUC 0.82 (95% CI 0.76-0.87) vs. 0.77 (95% CI 0.71-0.83), p=0.005. Addition of vitamin D to the model that included all significant factors for mortality improved the prognostic accuracy as showed by the metrics of reclassification (NRI 0.34 (95% CI 0.14-0.48), p=0.003 and IDI 0.06 (95% CI 0.01-0.12, p=0.005 p=0.03). CONCLUSIONS: We report a U-shaped relationship between vitamin D levels and long-term outcome of patients surviving AMI