Critical evaluation of equations for serum osmolality: Proposals for effective clinical utility.
Equations
Formula
Harmonization
Osmolal gap
Serum osmolality
Serum osmolarity
Standardization
Journal
Clinica chimica acta; international journal of clinical chemistry
ISSN: 1873-3492
Titre abrégé: Clin Chim Acta
Pays: Netherlands
ID NLM: 1302422
Informations de publication
Date de publication:
Nov 2020
Nov 2020
Historique:
received:
14
06
2020
revised:
26
06
2020
accepted:
26
06
2020
pubmed:
6
7
2020
medline:
22
6
2021
entrez:
6
7
2020
Statut:
ppublish
Résumé
Many studies have assessed the predictive accuracy of serum osmolality equations. Different approaches for selecting a usable equation were compared using thirty published equations and patient data from a regional hospital laboratory. Laboratory records were extracted with same-sample results for measured serum osmolality, sodium, potassium, urea and glucose analysed in a regional hospital laboratory between 1/1/2017-31/12/2018. Differences were analysed using Passing-Bablok and difference (Bland-Altman) analysis. Three approaches were compared: the shotgun approach, adjusting for bias, and deriving a novel equation using multivariate analysis. The criteria for success included bias ≤0.7%, a 230 - 400 mOsm/kg range, and osmolal gap (OG) 95% reference limits within ±10 mOsm/kg. The majority of equations produced proportionally negative-biased results. The shotgun approach identified two equations (EQ19, EQ6) with bias ≤0.7% but unworkable OG reference limits. The bias adjustment approach produced several equations with bias ≤ 0.7% and OG reference limits within or equivalent to ±10 mOsm/kg. A novel equation generated by us (1.89Na Few published equations are immediately usable. Adjustment of bias derives several usable equations of which the best had OG ranges <20 mOsm/kg. We conclude that adjustment of bias can generate equations of equal or superior performance to that of novel equations.
Sections du résumé
BACKGROUND
BACKGROUND
Many studies have assessed the predictive accuracy of serum osmolality equations. Different approaches for selecting a usable equation were compared using thirty published equations and patient data from a regional hospital laboratory.
METHODS
METHODS
Laboratory records were extracted with same-sample results for measured serum osmolality, sodium, potassium, urea and glucose analysed in a regional hospital laboratory between 1/1/2017-31/12/2018. Differences were analysed using Passing-Bablok and difference (Bland-Altman) analysis. Three approaches were compared: the shotgun approach, adjusting for bias, and deriving a novel equation using multivariate analysis. The criteria for success included bias ≤0.7%, a 230 - 400 mOsm/kg range, and osmolal gap (OG) 95% reference limits within ±10 mOsm/kg.
RESULTS
RESULTS
The majority of equations produced proportionally negative-biased results. The shotgun approach identified two equations (EQ19, EQ6) with bias ≤0.7% but unworkable OG reference limits. The bias adjustment approach produced several equations with bias ≤ 0.7% and OG reference limits within or equivalent to ±10 mOsm/kg. A novel equation generated by us (1.89Na
CONCLUSION
CONCLUSIONS
Few published equations are immediately usable. Adjustment of bias derives several usable equations of which the best had OG ranges <20 mOsm/kg. We conclude that adjustment of bias can generate equations of equal or superior performance to that of novel equations.
Identifiants
pubmed: 32622969
pii: S0009-8981(20)30307-7
doi: 10.1016/j.cca.2020.06.043
pii:
doi:
Substances chimiques
Urea
8W8T17847W
Sodium
9NEZ333N27
Potassium
RWP5GA015D
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
79-87Informations de copyright
Copyright © 2020 Elsevier B.V. All rights reserved.