# Elixhauser Comorbidity Measure and Charlson Comorbidity Index in Predicting the Death of Spanish Inpatients with Diabetes and Invasive Pneumococcal Disease

## TL;DR

This study examines how comorbidity indices predict mortality in Spanish patients with diabetes and invasive pneumococcal disease, finding that the Charlson index performs better than the Elixhauser index.

## Contribution

The study compares the Elixhauser and Charlson comorbidity indices in predicting mortality for diabetic patients with IPD in Spain, highlighting the superior predictive power of the Charlson index.

## Key findings

- The Charlson Comorbidity Index (CCI) outperformed the Elixhauser Comorbidity Index (ECI) in predicting in-hospital mortality for diabetic patients with IPD.
- Both ECI and CCI scores increased with age and were higher in type 2 diabetes compared to type 1 diabetes.
- Mortality risk was significantly associated with comorbidity indices, age, diabetes type, and the presence of IPD or COVID-19.

## Abstract

Invasive pneumococcal disease (IPD) is a serious infection caused by the bacterium Streptococcus pneumoniae (pneumococcus) that can produce a wide spectrum of clinical manifestations. The aim of this study was to analyze the comorbidity factors that influenced the mortality in patients with diabetes (D) according to IPD. A retrospective study to analyze patients with D and IPD was carried out. Based on the discharge reports from the Spanish Minimum Basic Data Set (MBDS) from 1997 to 2022, the Elixhauser Comorbidity Index (ECI) and the Charlson Comorbidity Index (CCI) were calculated to predict in-hospital mortality (IHM) in Spain. A total of 12,994,304 patients with D were included, and 84,601 cases of IPD were identified. The average age for men was 70.23 years and for women 73.94 years. In all years, ECI and CCI were larger for type 2 D than for type 1 D, with men having a higher mean than women. An association was found between risk factors ECI, age, type 1 D, COVID-19, IPD (OR = 1.31; 95% CI: 1.29–1.35; p < 0.001); CCI, age, type 1 D, COVID-19, IPD (OR = 1.45; 95% CI: 1.42–1.49; p < 0.001), and increased mortality. The IHM increased steadily with the number of comorbidities and index scores from 1997 to 2022. D remains a relevant cause of hospitalization in Spain. Comorbidities reflected a great impact on patients with D and IPD, which would mean a higher risk of mortality. Predicting mortality events and length of stay by comparing indices showed that CCI outperforms ECI in predicting inpatient death after IPD.