Validation and Comparison of a Modified Elixhauser Index for Predicting In-Hospital Mortality in Italian Internal Medicine Wards

Purpose: Burden of comorbidities appears to be related to clinical outcomes in hospitalized patients. Clinical stratification of admitted patients could be obtained calculating a comorbidity score, which represents the simplest way to identify the severity of patients' clinical conditions and a practical approach to assess prevalent comorbidities. Our aim was to validate a modified Elixhauser score for predicting in-hospital mortality (IHM) in internal medicine admissions and to compare it with a different one derived from clinical data previously used in a similar setting, having a good prognostic accuracy.Patients and Methods: A single-center retrospective study enrolled all patients admitted to internal medicine department between January and June 2016. A modified Elixhauser score was calculated from chart review and administrative data; moreover, a second prognostic index was calculated from chart review only. Comorbidity scores were compared using c-statistic.Results: We analyzed 1614 individuals without selecting the reason for admission, 224 (13.9%) died during hospital stay. Deceased subjects were older (83.3 +/- 9.1 vs 78.4 +/- 13.5 years; p<0.001) and had higher burden of comorbidities. The modified Elixhauser score calculated by administrative data and by chart review and the comparator one was 18.13 +/- 9.36 vs 24.43 +/- 11.27 vs 7.63+3.3, respectively, and the c-statistic was 0.758 (95% CI 0.727-0.790), 0.811 (95% CI 0.782-0.840) and 0.740 (95% CI 0.709-0.771), respectively.Conclusion: The new modified Elixhauser score showed a similar performance to a previous clinical prognostic index when it was calculated using administrative data; however, its performance improved if calculation was based on chart review.