Hyponatremia as an early marker of poor outcome of stroke - results of a prospective cohort study

Background & Objective: Hyponatremia is a frequently found complication of stroke. However, its impact on stroke outcome is poorly understood. Hence, the purpose of this study was to determine the outcome of strokes in association with hyponatremia. Methods: This was a prospective cohort study conducted at a tertiary referral center in Sri Lanka. The study subjects consisted of 246 patients with confirmed stroke. Patient characteristics, mortality, length of hospital stay and functional outcome by Modified Rankin Scale (MRS) score were assessed to evaluate the effect of hyponatremia (<131mmol/l) on stroke. Early mortality was defined as the total number of deaths occurred by 70 days. The “not favorable” MRS score was defined from 4 to 6. Results: Out of 246 patients, 47 patients (19.1%) developed hyponatremia (95% confidence interval (CI): 14.39, 24.58). The mean day of development of hyponatremia was 1.81days (SD=1.73). Hyponatremia was associated with early mortality (OR=2.08; 95% CI: 1.05, 4.1; P=0.034), increased length of hospital stay (β=2.37; 95% CI: 1.51, 3.23; P= <0.001) and “not favourable” functional outcome at discharge (OR=2.59; 95% CI: 1.33, 5.05; P=0.005). Kaplan Meier survival curve analysis showed better chance of survival in non-hyponatremic group compared to hyponatremic group (P =0.02). Conclusion: Hyponatremia is associated with early mortality, increased length of hospital stay and unfavorable functional outcome at discharge following stroke. Early detection and correction of hyponatremia may improve stroke outcome.