The relationship between serum anion levels and mortality of hypertensive patients; a retrospective cohort

Background: There is still controversy regarding the role of chloride ion and other serum ions in prediction of mortality in patients with hypertension. Therefore, the present study was planned out with the aim of assessing the relationship of serum levels of chloride, bicarbonate, sodium, and potassium ions with mortality in hypertensive patients. Methods: The present retrospective cohort was carried out on patients with hypertension presenting to a heart clinic in Tehran, Iran. Data were gathered by an acute care nurse practitioner using patients’ medical profiles. Serum levels of chloride, bicarbonate, sodium, and potassium ions were assessed on the first visit and the correlation of these ions with 2-year mortality of the patients was evaluated by reporting hazard ratio (HR) with 95% confidence interval (95%CI). Results: Finally, data of 893 individuals were assessed (73.91% male; mean age 49.52±15.60 years). During the 2 years of follow up, 67 (7.5%) cases of death was observed. Cox regression analysis showed that compared to normal levels of bicarbonate, decrease in this ion to measures less than 22 mEq/L leads to increased risk of mortality in hypertensive patients (HR=10.31; p<0.0001). This analysis showed that decrease of serum chloride ion to less than 97mEq/L also increases the risk of mortality in patients with high blood pressure (HR=2.89; p=0.001). However, there was no correlation between serum levels of sodium or potassium and incidence of mortality in patients (p>0.05). Conclusion: For the first time, the findings of the present study showed that serum anion levels play an important role in incidence of mortality among patients with hypertension and can therefore be used for risk stratification of hypertensive patients