Anion gap and cancer mortality: Insight from NHANES database.

e13068 Background: The serum anion gap is an effective tool to analyze acid- base disorders for the past 40 years. Anion gap and non-anion gap acidosis is prevalent in cancer patients and contributes to morbidity and mortality The aim of the present study was to investigate the independent association of serum anion gap with cancer mortality. Methods: We examined the 34,370 participants ( ≥ 20years of age) using National Health and Nutrition Examination survey data (1999-2010) combined with National Death Index for mortality status through December 2011.The serum anion gap was calculated by subtracting sum of chloride and bicarbonate from sodium concentrations in meq/l. We divided the data set in to four quartiles of serum anion gap. Cox proportional hazard models were made to estimate the hazard ratios for cancer mortality for each unit increase in serum anion gap. The models were adjusted from demographic and confoundig variables. Results: The mean age of participants was 49.59±18.42 years. Out of total population 33,717(98.1%) were alive and 651 (1.9%) were dead secondary to cancer. The mean period of follow up was 5.55±3.53 years. In univariate regression model using serum anion gap as continuous variable, we found 6% (HR-1.06;95%CI,1.0-1.1), increase in cancer mortality with each unit increase in serum anion gap. After adjusting for potential confounders using multivariate regression model we found 8%(HR-1.08;95%CI,1.03-1.14), increase in cancer mortality with each unit increase in serum anion gap. In univariate regression model using quartiles, we found 47% (HR-1.47;95%CI,1.04-1.93), increase in cancer mortality with each unit increase in serum anion gap in highest quartile compared to the lowest quartile. After adjusting to the potential confounders the risk for cancer mortality increases to 60% in highest quartile comparison to lowest quartile (HR-1.60;95%CI,1.12-2.26). Conclusions: We found a linear association between serum anion gap and cancer mortality. A high serum anion gap is associated with increase in cancer mortality and may be the prognostic indicator of cancer mortality in general population. This should be validated by performing further investigation.