The association between caffeine intake and mortality among patients with chronic kidney disease: A population-based study

Background The benefits of caffeine to human health have been widely reported, but the association between caffeine intake and mortality among patients with chronic kidney disease (CKD) has been rarely studied in large epidemiologic studies. Thus, we aimed to investigate the association between caffeine intake and mortality among CKD patients. Methods Our study was based on non-dialysis CKD patients in 2003–2016 National Health and Nutrition Examination Survey (NHANES). Weighted COX regression analysis was applied to explore the linear relationship between caffeine intake and mortality (including all-cause mortality, cardiovascular mortality, cancer mortality, cerebrovascular mortality, nephropathy mortality and influenza and pneumonia mortality). Restricted cubic spline analysis was performed to explore the nonlinear relationship. Finally, threshold effects were analyzed with two-piecewise linear regression. Results In the fully adjusted model, there was no significant linear association between caffeine intake and mortality. However, a U-shaped nonlinear association between caffeine intake and all-cause mortality (inflection point = 277mg) was identified. Moreover, there was a J-shaped association between caffeine intake and cardiovascular mortality (inflection point = 252mg) and cancer mortality (inflection point = 79mg). Conclusion Moderate caffeine intake shows a protective effect on the prognosis of CKD patients. However, excessive caffeine intake was associated with increased all-cause mortality, cardiovascular mortality and cancer mortality.