Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients

Objective To evaluate the validity of the International Classification of Diseases, 10th Revision (ICD-10) diagnosis code for hyponatraemia (E87.1) in two settings: at presentation to the emergency department and at hospital admission.Design Population-based retrospective validation study.Setting Tw...

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Main Authors: Amit X Garg, Salimah Z Shariff, Sonja Gandhi, Jamie L Fleet, Matthew A Weir, Arsh K Jain
Format: Article
Language:English
Published: BMJ Publishing Group 2012-12-01
Series:BMJ Open
Online Access:https://bmjopen.bmj.com/content/2/6/e001727.full
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author Amit X Garg
Salimah Z Shariff
Sonja Gandhi
Jamie L Fleet
Matthew A Weir
Arsh K Jain
author_facet Amit X Garg
Salimah Z Shariff
Sonja Gandhi
Jamie L Fleet
Matthew A Weir
Arsh K Jain
author_sort Amit X Garg
collection DOAJ
description Objective To evaluate the validity of the International Classification of Diseases, 10th Revision (ICD-10) diagnosis code for hyponatraemia (E87.1) in two settings: at presentation to the emergency department and at hospital admission.Design Population-based retrospective validation study.Setting Twelve hospitals in Southwestern Ontario, Canada, from 2003 to 2010.Participants Patients aged 66 years and older with serum sodium laboratory measurements at presentation to the emergency department (n=64 581) and at hospital admission (n=64 499).Main outcome measures Sensitivity, specificity, positive predictive value and negative predictive value comparing various ICD-10 diagnostic coding algorithms for hyponatraemia to serum sodium laboratory measurements (reference standard). Median serum sodium values comparing patients who were code positive and code negative for hyponatraemia.Results The sensitivity of hyponatraemia (defined by a serum sodium ≤132 mmol/l) for the best-performing ICD-10 coding algorithm was 7.5% at presentation to the emergency department (95% CI 7.0% to 8.2%) and 10.6% at hospital admission (95% CI 9.9% to 11.2%). Both specificities were greater than 99%. In the two settings, the positive predictive values were 96.4% (95% CI 94.6% to 97.6%) and 82.3% (95% CI 80.0% to 84.4%), while the negative predictive values were 89.2% (95% CI 89.0% to 89.5%) and 87.1% (95% CI 86.8% to 87.4%). In patients who were code positive for hyponatraemia, the median (IQR) serum sodium measurements were 123 (119–126) mmol/l and 125 (120–130) mmol/l in the two settings. In code negative patients, the measurements were 138 (136–140) mmol/l and 137 (135–139) mmol/l.Conclusions The ICD-10 diagnostic code for hyponatraemia differentiates between two groups of patients with distinct serum sodium measurements at both presentation to the emergency department and at hospital admission. However, these codes underestimate the true incidence of hyponatraemia due to low sensitivity.
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spelling doaj-art-a3a3f40af56b476fb155876abb34ff332025-08-20T03:53:01ZengBMJ Publishing GroupBMJ Open2044-60552012-12-012610.1136/bmjopen-2012-001727Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patientsAmit X Garg0Salimah Z Shariff1Sonja Gandhi2Jamie L Fleet3Matthew A Weir4Arsh K Jain52 Institute for Clinical Evaluative Sciences, Ontario, CanadaICES Western, Toronto, Ontario, Canada1Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada1Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada1Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada1Division of Nephrology, Department of Medicine, Western University, London, Ontario, CanadaObjective To evaluate the validity of the International Classification of Diseases, 10th Revision (ICD-10) diagnosis code for hyponatraemia (E87.1) in two settings: at presentation to the emergency department and at hospital admission.Design Population-based retrospective validation study.Setting Twelve hospitals in Southwestern Ontario, Canada, from 2003 to 2010.Participants Patients aged 66 years and older with serum sodium laboratory measurements at presentation to the emergency department (n=64 581) and at hospital admission (n=64 499).Main outcome measures Sensitivity, specificity, positive predictive value and negative predictive value comparing various ICD-10 diagnostic coding algorithms for hyponatraemia to serum sodium laboratory measurements (reference standard). Median serum sodium values comparing patients who were code positive and code negative for hyponatraemia.Results The sensitivity of hyponatraemia (defined by a serum sodium ≤132 mmol/l) for the best-performing ICD-10 coding algorithm was 7.5% at presentation to the emergency department (95% CI 7.0% to 8.2%) and 10.6% at hospital admission (95% CI 9.9% to 11.2%). Both specificities were greater than 99%. In the two settings, the positive predictive values were 96.4% (95% CI 94.6% to 97.6%) and 82.3% (95% CI 80.0% to 84.4%), while the negative predictive values were 89.2% (95% CI 89.0% to 89.5%) and 87.1% (95% CI 86.8% to 87.4%). In patients who were code positive for hyponatraemia, the median (IQR) serum sodium measurements were 123 (119–126) mmol/l and 125 (120–130) mmol/l in the two settings. In code negative patients, the measurements were 138 (136–140) mmol/l and 137 (135–139) mmol/l.Conclusions The ICD-10 diagnostic code for hyponatraemia differentiates between two groups of patients with distinct serum sodium measurements at both presentation to the emergency department and at hospital admission. However, these codes underestimate the true incidence of hyponatraemia due to low sensitivity.https://bmjopen.bmj.com/content/2/6/e001727.full
spellingShingle Amit X Garg
Salimah Z Shariff
Sonja Gandhi
Jamie L Fleet
Matthew A Weir
Arsh K Jain
Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
BMJ Open
title Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
title_full Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
title_fullStr Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
title_full_unstemmed Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
title_short Validity of the International Classification of Diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
title_sort validity of the international classification of diseases 10th revision code for hospitalisation with hyponatraemia in elderly patients
url https://bmjopen.bmj.com/content/2/6/e001727.full
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