Development and validation of comorbidity index in South Korea

Kil, Seol-Ryoung
Lee, Sang-Il
Khang, Young-Ho
Lee, Moo-Song
Kim, Hwa-Jung
Kim, Seon-Ok
Jo, Min-Woo

¹Department of Preventive Medicine, Ulsan University College of Medicine, Seoul, Republic of Korea
²Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, Seoul, Republic of Korea

Address reprint requests to: Min-Woo Jo, Department of Preventive Medicine, University of Ulsan College of Medicine, 86 Asanbyeongwon-gil, Songpa-Gu, Seoul 138-736, Korea. Tel: +82-2-3010-4264; Fax: +82-2-477-2898; E-mail: [email protected]

Accepted May 3, 2012

International Journal for Quality in Health Care 24(4):p 391-402, August 2012. | DOI: 10.1093/intqhc/mzs027

Objective

This study aims to develop and validate a new comorbidity index using data from hospitalized patients in South Korea.

Study design

Retrospective cohort study.

Setting

Hospital inpatients.

Study participants

Data from 4677 hospitalized patients aged 40–79 who had admitted in a medical center in Korea between September and December in 1997 were individually linked to national mortality data through December 2007. Among them, 3274 patients (70%) were randomly included in the development data set and the other 1403 patients (30%) in the validation data set. Another 3413 liver cancer patients from the same hospital were used to validate the index.

Main measures

Comorbidity index and mortality risk.

Results

Based on mortality using stratified Cox regression analyses, comorbidity scores ranging from 1 to 4 were assigned for 20 comorbid conditions. Summation of the scores produced the new comorbidity index (Asan comorbidity index, ACI). C-indices in the Cox regression analyses showed the greatest increase [0.589 (95% confidence interval, 0.568–0.609) in age- and sex-adjusted model; 0.697 (0.678–0.716) in the ACI and 0.664 (0.645–0.684) in the Charlson comorbidity index, respectively] when the ACI was added in the validation models.

Conclusions

A newly developed comorbidity index using Korean hospitalized patient data based on the International Classification of Disease, 10th Revision (ICD-10) was valid among both general medical inpatients and liver cancer patients. This index may well be widely used in various health-care settings in Korea where patients' information on health conditions is coded with ICD-10.