The association between serum anion gap and all‐cause mortality of unselected adult patients: A retrospective cohort study of >20,000 patients

BACKGROUND: Even though the serum anion gap (AG) is frequently measured in clinical practice, there is not much research that has examined long‐term mortality in unselected adult patients. Our study's objective was to investigate how serum anion gap levels could be used to predict death in unselected participants. METHODS: The relationship between baseline serum AG levels and short‐, intermediate‐, and long‐term all‐cause mortality in unselected adult patients is examined using the Cox proportional risk analysis, smoothed curve fitting, subgroup analysis, and Kaplan–Meier survival curves. RESULTS: After screening the database using the appropriate method, a total of 26,270 patients were enrolled in our study for the final data analysis. Our study used smoothed curve fit plots and COX proportional risk regression models incorporating cubic spline functions to evaluate the association between AG levels and all‐cause mortality in a non‐selected population, and the results indicated a non‐linear relationship. In the fully adjusted model, we found that AG levels were positively associated with 30‐day, 90‐day, 365‐day, and 4‐year all‐cause mortality in unselected adult patients with HRs of 1.08 95% CIs (1.06, 1.09); 1.08 95% CIs (1.06, 1.09); 1.08 95% CIs (1.07, 1.08); 1.07 95% CIs (1.06, 1.07). CONCLUSION: Serum anion gap levels were positively correlated with all‐cause mortality in unselected adult patients, with increasing levels of serum anion gap increasing patient mortality.