title: The effect of comorbidity on hospital mortality in patients with SLE from an Asian tertiary hospital.
abstract: OBJECTIVE
  The objective of the study was to assess the disease burden of systemic lupus erythematosus (SLE) and the usefulness of the Charlson Comorbidity Index (CCI) as risk-adjusted hospital mortality predictors in patients with SLE using a hospital administrative database.
  
  
  METHODS
  A historical cohort study of a hospital discharge database from 2004 to 2011 was used to identify cases with SLE and comorbidity using the International Statistical Classification of Diseases and Related Health Problems, ninth revision, Australian modification (ICD-9-AM) codes.
  
  
  RESULTS
  Over the eight years, 841 patients met the criteria of SLE with a hospital mortality rate of 9.2%. The hospital mortality rates (2.4%, 15.7%, 25.0%, and 30.4%, respectively, p < 0.001) and hospital length of stay (geometric mean, 3.5, 5.6, 8.8, and 7.5 days, respectively, p < 0.001) were consistently increased for patients with CCI ranging from none, low, moderate to high grade, respectively. Cox proportional hazards model analysis showed that CCI (hazard ratio (HR) 7.8 high vs. none, p < 0.001) and infectious disease (HR 2.0, p = 0.016) were significant and independent predictors of hospital mortality. Similar results were also seen with hospital length of stay by zero-truncated negative binomial regression model analysis.
  
  
  CONCLUSIONS
  The SLE burden is high in this population. Comorbidities and infectious disease were some of the most important contributors to hospital mortality and resource utilization.
authors: Department of Epidemiology, Medical Board, Singapore General Hospital, Singapore Centre for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore yang.yong@sgh.com.sg.
authors: Y
authors: Y
authors: Yang
authors: Department of Rheumatology & Immunology, Singapore General Hospital, Singapore Duke-NUS Graduate Medical School, Singapore.
authors: J
authors: J
authors: Thumboo
authors: Centre for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.
authors: A
authors: A
authors: Earnest
authors: Medical Board, Singapore General Hospital, Singapore.
authors: S L
authors: SL
authors: Yong
authors: Department of Rheumatology & Immunology, Singapore General Hospital, Singapore Duke-NUS Graduate Medical School, Singapore.
authors: K Y
authors: KY
authors: Fong
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012720:Severity of Illness Index; D012846:Singapore; D062606:Tertiary Care Centers
keywords: Charlson Comorbidity Index; ICD-9-AM; SLE; hospital mortality; length of stay