Supplemental Material for: Ratio of red blood cell distribution width to albumin level and mortality outcomes in population with chronic kidney disease

Methods

Data from the National Health and Nutrition Examination Survey 1999 to 2018 and the National Death Index were employed for cohort analysis. A total of 3965 patients with CKD were identified in this study. The associations of RAR with mortality outcomes including all-cause mortality, cardiovascular disease (CVD) mortality, and cancer mortality were investigated through multivariable Cox regression.

Restricted cubic spline (RCS) analysis was applied to observe dose-response relationships and thresholds. Subgroup analysis was performed to find potential interactive factors.</p><p dir="ltr">Results: 1163 fatal events occurred during the follow-up period. Multivariable Cox regression revealed RAR was independently associated with all-cause mortality (HR, 1.81, 95%CI, 1.60 – 2.06, P < 0.001), CVD mortality (HR, 1.89, 95%CI, 1.59 – 2.26, P < 0.001), and cancer mortality (HR, 1,76, 95%CI, 1.46 - 2.11, P < 0.001).

Non-linear relationships for all-cause mortality (P for non-linear < 0.001) and CVD mortality (P for non-linear < 0.001) were observed via RCS analysis, while a linear relationship was observed for cancer mortality (P for non-linear = 0.113). Age, gender, urine albumin-to-creatinine ratio and poverty income ratio potentially interacted with RAR.</p><p dir="ltr">Conclusion: These findings suggested that increased RAR robustly associated with elevated risks for all-cause and cause-specific mortality in CKD population.

Future clinical trials are demanded to validate the present findings and figure out the underlying mechanisms.</p>