Email updates

Keep up to date with the latest news and content from BMC Medical Research Methodology and BioMed Central.

Open Access Research article

The predictive value of ICD-10 diagnostic coding used to assess Charlson comorbidity index conditions in the population-based Danish National Registry of Patients

Sandra K Thygesen1*, Christian F Christiansen1, Steffen Christensen1, Timothy L Lash12 and Henrik T Sørensen12

Author Affiliations

1 Department of Clinical Epidemiology, The Institute of Clinical Medicine, Aarhus University Hospital, Denmark

2 Department of Epidemiology, Boston University School of Public Health, USA

For all author emails, please log on.

BMC Medical Research Methodology 2011, 11:83  doi:10.1186/1471-2288-11-83

Published: 28 May 2011

Abstract

Background

The Charlson comorbidity index is often used to control for confounding in research based on medical databases. There are few studies of the accuracy of the codes obtained from these databases.

We examined the positive predictive value (PPV) of the ICD-10 diagnostic coding in the Danish National Registry of Patients (NRP) for the 19 Charlson conditions.

Methods

Among all hospitalizations in Northern Denmark between 1 January 1998 and 31 December 2007 with a first-listed diagnosis of a Charlson condition in the NRP, we selected 50 hospital contacts for each condition. We reviewed discharge summaries and medical records to verify the NRP diagnoses, and computed the PPV as the proportion of confirmed diagnoses.

Results

A total of 950 records were reviewed. The overall PPV for the 19 Charlson conditions was 98.0% (95% CI; 96.9, 98.8). The PPVs ranged from 82.0% (95% CI; 68.6%, 91.4%) for diabetes with diabetic complications to 100% (one-sided 97.5% CI; 92.9%, 100%) for congestive heart failure, peripheral vascular disease, chronic pulmonary disease, mild and severe liver disease, hemiplegia, renal disease, leukaemia, lymphoma, metastatic tumour, and AIDS.

Conclusion

The PPV of NRP coding of the Charlson conditions was consistently high.