Abstract
Introduction
In recent years the relationship between hyponatraemia and bone metabolism, falls and fractures has become more established. In this study hyponatraemia was an independent risk factor for increased post-operative mortality on multivariate analysis.
Patients/Materials & Methods
This study retrospectively evaluates the prevalence of hyponatraemia (plasma sodium <135 mmol/l) in 3897 patients undergoing operative treatment for hip fracture and the relationship between hyponatraemia and mortality in these patients.
Results
Median age at admission was 83 years. Hyponatraemia was present in 19.1% of patients with hip fracture on admission, 29.5% of patients within the first 24 hours post-operatively and 20% of patients at discharge. There was a significant association between hyponatraemia and time from admission to surgery indicating that patients admitted with hyponatraemia waited longer. Median follow-up time was 863 (range 0 – 4352) days. There were 2460 deaths (63.1% of the original 3897 patients) prior to the censor date. A total of 1144 patients (29.4% of the original 3897 patients) died within 12 months following discharge. Median survival following surgery was 39 weeks. Median time to death for patients with and without hyponatraemia on admission was 34 months (SE 1.7months) and 41 months (SE 2.5 months) respectively (p = 0.003). Median time to death for patients with and without hyponatraemia within 24 hours post-operatively was 35 months (SE 2.5 months) and 42 months (SE 1.7 months) respectively (p = 0.004). Following elimination of other independent variables associated with increased mortality, hyponatraemia on admission was associated with an increased risk of death (adjusted HR 1.15, p = 0.005). Post-operative hyponatraemia was also associated with an increased risk of death (adjusted HR 1.15, p = 0.006).
Conclusion
Hyponatraemia is common in elderly patients with hip fractures both at initial presentation and during admission and is a potentially reversible cause of increased post-operative mortality.
