Hyponatraemia as a predictor of mortality in medical admissions in Ghana - A case control study

Abstract Background Hyponatraemia is the most common electrolyte abnormality in hospital admissions. It occurs in a quarter of medical admissions in Ghana and its associated with high mortality. Mortality has been suggested to be due to the underlying medical condition and not necessarily the hyponatraemia. We set out to compare the outcomes of patients with documented hyponatraemia as compared to those with normonatraemia in terms of mortality and length of hospital stay.Methods We conducted a case control study of patients with hyponatraemia as compared to those with normonatraemia on the medical ward at the Komfo Anokye Teaching hospital between May 2018 to December 2018. The medical diagnoses, demographics and laboratory data of the patients were recorded. Participants’ age and gender were matched. Student t test was used to test for differences in continuous variables when parametric and Wilcoxon Signed Rank test for non-parametric variables. Multiple logistic regression was used to identify predictors of mortality. A p value of <0.05 was considered statistically significant.Results Within the study period there were 846 patients recruited. This included 406 patients with hyponatraemia and 440 patients as controls. Serum albumin and protein were significantly lower in the hyponatraemia patients as compared to those with normal sodium concentration. The mortality rate in patients with hyponatraemia was significantly higher than those with normonatraemia 129 (31.8%) vs 98 (22.3%) [OR 1.62 (CI 1.19-2.22) p=0.002]. In-hospital stay was longer in patients with hyponatraemia than normonatraemia 7 (4-10) vs 6 (3-10) but not statistically significant (p=0.09). Multiple logistic regression showed that low serum sodium concentration (p<0.001) and low serum albumin concentration (p=0.009) were the predictors of in-hospital mortality.Conclusion Hyponatraemia is associated with significantly higher mortality than normonatraemia and predicts worse prognosis in patients on medical admission. Low serum albumin is also a predictor of mortality in medical admission.