Association of Red Blood Cell Distribution Width to Albumin Ratio With the Prevalence of Kidney Stones Among the General Adult Population

Background: The red blood cell distribution width (RDW) and serum albumin levels are potential indicators of inflammatory conditions. However, the relationship between the RDW to albumin ratio (RAR) and the prevalence of kidney stones in the general adult population is not yet established. Methods: This study utilized data from the 2007 to 2018 National Health and Nutrition Examination Survey (NHANES) project. RAR levels were calculated by dividing RDW by albumin. Multiple logistic regressions and restricted cubic spline (RCS) regression were applied to examine the associations between RDW, albumin, RAR, and the prevalence of kidney stones. Results: A total of 31,417 adults (2987 participants with kidney stones) were included for analysis. The mean age of the participants was 47.84 +/- 0.23 years, and 48.86% were male. The mean of RDW, albumin, and RAR was 13.25 +/- 0.02%, 4.26 +/- 0.01 g/dL, and 3.14 +/- 0.01, respectively. Compared to the first quartile, the fourth quartile of RDW (OR = 1.44 [1.21-1.72], P-trend < 0.001) and RAR (OR = 1.62 [1.35-1.95], P-trend < 0.001) were positively associated with the prevalence of kidney stones, whereas albumin (OR = 0.75 [0.63-0.89], P-trend < 0.001) was negatively associated with the prevalence of kidney stones after multivariable adjustment. Furthermore, we found that both RDW and RAR levels were positively and non-linearly related to the prevalence of kidney stones, with inflection points of 13.50% and 3.23, respectively. On the other hand, serum albumin concentrations exhibited a linear association with the prevalence of kidney stones. Conclusion: Our findings suggest that higher RAR levels are associated with an increased prevalence of kidney stones in the general adult population.