Journal Article

Coding Algorithms for Defining Comorbidities in ICD-9-CM and ICD-10 Administrative Data

L. Duncan Saunders, Bernard Burnand, William A. Ghali, Hude Quan, Vijaya Sundararajan, Patricia Halfon, Cynthia A. Beck, Andrew Fong, Thomas E. Feasby, Jean-Christophe Luthi

2005

Overview

Objectives: Implementation of the International Statistical Classification of Disease and Related Health Problems, 10th Revision (ICD-10) coding system presents challenges for using administrative data. Recognizing this, we conducted a multistep process to develop ICD-10 coding algorithms to define Charlson and Elixhauser comorbidities in administrative data and assess the performance of the resulting algorithms. Methods: ICD-10 coding algorithms were developed by \"translation\" of the ICD-9-CM codes constituting Deyo's (for Charlson comorbidities) and Elixhauser's coding algorithms and by physicians' assessment of the face-validity of selected ICD-10 codes. The process of carefully developing ICD-10 algorithms also produced modified and enhanced ICD-9-CM coding algorithms for the Charlson and Elixhauser comorbidities. We then used data on in-patients aged 18 years and older in ICD-9-CM and ICD-10 administrative hospital discharge data from a Canadian health region to assess the comorbidity frequencies and mortality prediction achieved by the original ICD-9-CM algorithms, the enhanced ICD-9-CM algorithms, and the new ICD-10 coding algorithms. Results: Among 56,585 patients in the ICD-9-CM data and 58,805 patients in the ICD-10 data, frequencies of the 17 Charlson comorbidities and the 30 Elixhauser comorbidities remained generally similar across algorithms. The new ICD-10 and enhanced ICD-9-CM coding algorithms either matched or outperformed the original Deyo and Elixhauser ICD-9-CM coding algorithms in predicting in-hospital mortality. The C-statistic was 0.842 for Deyo's ICD-9-CM coding algorithm, 0.860 for the ICD-10 coding algorithm, and 0.859 for the enhanced ICD-9-CM coding algorithm, 0.868 for the original Elixhauser ICD-9-CM coding algorithm, 0.870 for the ICD-10 coding algorithm and 0.878 for the enhanced ICD-9-CM coding algorithm. Conclusions: These newly developed ICD-10 and ICD-9-CM comorbidity coding algorithms produce similar estimates of comorbidity prevalence in administrative data, and may outperform existing ICD-9-CM coding algorithms.

• Publisher: J. B. Lippincott Williams and Wilkins Inc,Lippincott Williams & Wilkins, Inc,Lippincott Williams & Wilkins Ovid Technologies
• Subject: Algorithms / Canada - epidemiology / Chronic kidney failure / Clinical coding / Comorbidity / Data coding / Diabetic angiopathies / Diabetic nephropathies / Disease - classification / Female / Forms and Records Control - methods / Health problems / Hospital Mortality / Humans / International Classification of Diseases / International Statistical Classification of Diseases / Lung diseases / Male / Medical Records - classification / Middle Aged / Models, Statistical / Morbidity / Mortality / Performance assessment / Risk Adjustment / Vascular diseases