Clinical Epidemiology (Jun 2017)
Charlson comorbidity index derived from chart review or administrative data: agreement and prediction of mortality in intensive care patients
Abstract
Knut Stavem,1–3 Henrik Hoel,4 Stein Arve Skjaker,5 Rolf Haagensen6 1Institute of Clinical Medicine, University of Oslo, Oslo, 2Department of Pulmonary Medicine, Medical Division, 3Health Services Research Unit, Akershus University Hospital, Lørenskog, 4Department of Surgery, Sykehuset Innlandet Kongsvinger, Kongsvinger, 5Section of Orthopaedic Emergency, Department of Orthopaedic Surgery, Oslo University Hospital, Oslo, 6Department of Anaesthesiology, Surgical Division, Akershus University Hospital, Lørenskog, Norway Purpose: This study compared the Charlson comorbidity index (CCI) information derived from chart review and administrative systems to assess the completeness and agreement between scores, evaluate the capacity to predict 30-day and 1-year mortality in intensive care unit (ICU) patients, and compare the predictive capacity with that of the Simplified Acute Physiology Score (SAPS) II model.Patients and methods: Using data from 959 patients admitted to a general ICU in a Norwegian university hospital from 2007 to 2009, we compared the CCI score derived from chart review and administrative systems. Agreement was assessed using % agreement, kappa, and weighted kappa. The capacity to predict 30-day and 1-year mortality was assessed using logistic regression, model discrimination with the c-statistic, and calibration with a goodness-of-fit statistic.Results: The CCI was complete (n=959) when calculated from chart than from administrative data (n=839). Agreement was good, with a weighted kappa of 0.667 (95% confidence interval: 0.596–0.714). The c-statistics for categorized CCI scores from charts and administrative data were similar in the model that included age, sex, and type of admission: 0.755 and 0.743 for 30-day mortality, respectively, and 0.783 and 0.775, respectively, for 1-year mortality. Goodness-of-fit statistics supported the model fit.Conclusion: The CCI scores from chart review and administrative data showed good agreement and predicted 30-day and 1-year mortality in ICU patients. CCI combined with age, sex, and type of admission predicts mortality almost as well as the physiology-based SAPS II. Keywords: epidemiology, Charlson comorbidity index, intensive care unit, comorbidity, mortality, SAPS II, case-mix adjustment, agreement, calibration, discrimination, prediction
