Addition of sodium criterion to SOAR stroke score
Acute stroke mortality remains high1 with most deaths occurring early as inpatient deaths.2 Numerous prognostic scores previously developed are limited by various factors including complexity 3 and prediction limited to either ischaemic or haemorrhagic stroke.4 We developed the SOAR stroke score as a simple eight point (score values 0–7) prognostic score that predicts inpatient and 7‐day mortality for both stroke subtypes. It takes into account four readily available variables: Stroke subtype, Oxfordshire Community Stroke Project (OCSP) Classification, age and prestroke modified Rankin score (prestroke mRs; indicative of prestroke disability). Haemorrhagic, and total anterior circulation stroke (TACS), older age and extensive prestroke disability are weighted with a higher score and are associated with greater risk for early mortality.8 Table S1 demonstrates how values for these variables are scored (along with the proposed scores for sodium categories). Although not currently in clinical use, external validation of the SOAR stroke score has shown that it is accurate in predicting mortality.9
Dysnatremia, either hypo‐ or hypernatraemia, is the commonest electrolyte abnormality in hospitalized patients.10 Indeed, both hypo‐ and hypernatraemia have been shown to increase inpatient mortality in various settings including intensive care units and emergency departments.10 Recently, studies have established that hyponatremia increases both short‐ and long‐term mortality in stroke patients.13 We hypothesize that the addition of sodium levels would improve the performance of SOAR stroke score.
This study aimed to examine if the addition of sodium levels (forming the SOAR‐Na score) would considerably better the prognostic ability of the SOAR stroke score. Also of interest was to explore the performance of the SOAR‐Na score in comparison to the SOAR stroke score in patient populations characterized by conditions that may particularly influence sodium handling and levels – those with or without chronic kidney disease (CKD) and those with or without hyperglycaemia, respectively.