['The syndrome of inappropriate antidiuresis (SIAD) is the commonest cause of euvolaemic hyponatraemia in patients admitted to hospital. The mortality after discharge from hospital has not been previously studied in patients with SIAD.', 'To compare mortality in patients with SIAD and those with kidney injury (KI). To identify underlying diagnoses associated with deaths due to SIAD.', 'Single-centre retrospective cohort analyses of 804 patients with severe hyponatraemia over a 3-year period. Five-year survival data in patients with SIAD and those with KI were compared. The underlying diagnoses that contributed to SIAD in this cohort were analysed using ICD-10 codes.', '202 patients had SIAD using biochemical cut-off parameters; 248 patients had KI. Patient with KI had a statistically significant (log-rank p<0.0001) shorter median survival time (2.24\u2005months (95% CI 1.3 to 4.3)) compared with those with SIAD (31.0\u2005months (95% CI 21.6 to 54.8)). 53.8% (n=78) of patients with hyponatraemia due to SIAD died within the first year after admission; the corresponding figure for those presenting with KI was 74.1% (n=166). Five years after admission, 80.8% (n=117) of those with SIAD had died; the corresponding figure for those with KI was 88.4% (n=200). In those patients with SIAD that died within the first year, malignancy appeared to be the most common cause (25.4%) followed by infection (23.8%).'] Is the syndrome of inappropriate antidiuresis associated with excess long-term mortality : a retrospective cohort analyses?