Development and Validation of a Comorbidity Scoring System for Patients With Cirrhosis

Background & AimsAt least 40% of patients with cirrhosis have comorbidities that increase mortality. We developed a cirrhosis-specific comorbidity scoring system (CirCom) to help determine how these comorbidities affect mortality and compared it with the generic Charlson Comorbidity Index.MethodsWe used data from nationwide health care registries to identify Danish citizens diagnosed with cirrhosis in 1999−2008 (n = 12,976). They were followed through 2010 and characterized by 34 comorbidities. We used Cox regression to assign severity weights to comorbidities with an adjusted mortality hazard ratio (HR) ≥1.20. Each patient's CirCom score was based on, at most, 2 of these comorbidities. Performance was measured with Harrell's C statistic and the Net Reclassification Index (NRI) and results were compared with those obtained using the Charlson Index (based on 17 comorbidities). Findings were validated in 2 separate cohorts of patients with alcohol-related cirrhosis or chronic hepatitis C.ResultsThe CirCom score included chronic obstructive pulmonary disease, acute myocardial infarction, peripheral arterial disease, epilepsy, substance abuse, heart failure, nonmetastatic cancer, metastatic cancer, and chronic kidney disease; 24.2% of patients had 1 or more of these, and mortality correlated with the CirCom score. Patients' CirCom score correlated with their Charlson Comorbidity Index (Kendall's τ = 0.57; P < .0001). Compared with the Charlson Index, the CirCom score increased Harrell's C statistic by 0.6% (95% confidence interval: 0.3%−0.8%). The NRI for the CirCom score was 5.2% (95% confidence interval: 3.7%−6.9%), and the NRI for the Charlson Index was 3.6% (95% confidence interval: 2.3%−5.0%). Similar results were obtained from the validation cohorts.ConclusionsWe developed a scoring system to predict mortality among patients with cirrhosis based on 9 comorbidities. This system had higher C statistic and NRI values than the Charlson Comorbidity Index, and is easier to use. It could therefore be a preferred method to predict death or survival of patients and for use in epidemiologic studies.