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Serum sodium level variability as a prognosticator in older adults

Lookup NU author(s): Professor Miles WithamORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by Taylor and Francis Ltd, 2019.

For re-use rights please refer to the publisher's terms and conditions.


© 2018, © 2018 Medisinsk Fysiologisk Forenings Forlag (MFFF). Our aim was to explore biological variation of serum sodium levels as a method of quantifying health risk in older adults. We investigated whether dynamic changes in serum sodium levels could provide additional prognostic information to standard predictors of mortality in older people. Analysis of routinely collected clinical datasets containing information on demographics, hospitalisation, biochemistry, haematology and physical function for Dundee in-patient rehabilitation services, between 1999 and 2011. Older people admitted to inpatient rehabilitation following an acute medical or surgical hospitalisation. Five dynamic measures of sodium levels homeostasis–minimum, maximum, standard deviation, and minimum and maximum deviation from mean–were derived for each individual, using biochemistry data from the year preceding their rehabilitation discharge. Cox regression models tested for associations with time to death. Covariates included age, sex, discharge Barthel score, co-morbid diagnoses, haemoglobin, albumin and eGFR. 3021 patients were included (mean age 84 years, 1776 (58.8%) females). 1651 (54.7%) patients experienced hyponatraemia and 446 (14.8%) became hypernatraemic. Mean sodium was correlated with all mean, minimum and SD of sodium. Kaplan–Meier survival curves showed that those without sodium perturbations had the best mortality outcomes, whilst those with both hyponatremia and hypernatremia had the worst. Multivariate Cox regression showed that standard deviation and hypernatraemia were significant predictors of death in non-adjusted models, but not fully adjusted models. All dynamic measures of dysnatraemia were associated with increased mortality risk, but failed to add predictive value to established static measures after adjusting for covariates.

Publication metadata

Author(s): Barma MA, Soiza RL, Donnan PT, McGilchrist MM, Frost H, Witham MD

Publication type: Article

Publication status: Published

Journal: Scandinavian Journal of Clinical and Laboratory Investigation

Year: 2019

Volume: 78

Issue: 7-8

Pages: 632-638

Online publication date: 03/01/2019

Acceptance date: 30/10/2018

Date deposited: 19/02/2019

ISSN (print): 0036-5513

ISSN (electronic): 1502-7686

Publisher: Taylor and Francis Ltd


DOI: 10.1080/00365513.2018.1543893


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