title: Comparison of different comorbidity measures for oral cancer patients with surgical intervention: A longitudinal study from a single cancer center.
abstract: OBJECTIVE
  Several comorbid measures have been developed and demonstrated the predictive ability for cancer mortality. We conducted a retrospective study on oral squamous cell carcinoma (OSCC) patients to compare the Charlson comorbidity index score (CCIS) to the Elixhauser comorbidity index score (ECIS).
  
  
  METHODS
  Newly diagnosed OSCC patients (n=232) post major surgery with or without adjuvant therapy were identified from the cancer registry database between 2006 and 2011. Comorbidities present prior to the cancer diagnosis were obtained and adapted to the CCIS and ECIS. The prevalence of comorbid conditions and the influence on disease-specific survival (DSS) rate were calculated and analyzed by Cox regression model. The discriminatory ability of these two comorbid measures was evaluated by using the adjusted hazard ratio and Akaike information criterion (AIC) in a multivariate regression model. The prediction accuracy was assessed using Harrell's c-statistic.
  
  
  RESULTS
  Most of the patients (93.5%) were male with a mean age of 54 ± 11 years and 77 of them (33.1%) had at least one comorbid condition. The ECIS was associated DSS, with an additional 10% increased risk observed for mortality for each increased score (HR, 1.10; 95% confidence interval [CI], 1.03-1.18) after adjusting with pathological risk features. However, the CCIS was not an independent prognostic factor for these patients. The ECIS increased discriminatory ability but the CCIS did not improve discrimination.
  
  
  CONCLUSIONS
  Comorbid conditions significantly influenced the clinical outcomes of patient with OSCC post major surgery. A higher ECIS was associated with worse disease specific survival indicative of a valuable prognostic indicator. The ECIS may be considered in further clinical trials for a variety of cancers, including head and neck cancers.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; School of Medicine, National Defense Medical Center, Taipei, Taiwan; Department of Otolaryngology, Head and Neck Surgery, Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: Ching-Chih
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Department of Otolaryngology, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan; School of Medicine, Tzu Chi University, Hualian, Taiwan.
authors.forename: Hsu-Chueh
authors.initials: HC
authors.lastname: Ho
authors.affiliation: School of Medicine, Tzu Chi University, Hualian, Taiwan; Division of Hematology-Oncology, Department of Internal Medicine, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Su
authors.affiliation: Department of Radiation Oncology, Pingtung Christian Hospital, Pingtung, Taiwan.
authors.forename: Po-Chun
authors.initials: PC
authors.lastname: Chen
authors.affiliation: Department of Medical Research, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
authors.forename: Chia-Hui
authors.initials: CH
authors.lastname: Yu
authors.affiliation: Department of Radiation Oncology, Chi-Mei Medical Center, Tainan, Taiwan; Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan. Electronic address: cleanclear0905@gmail.com.
authors.forename: Ching-Chieh
authors.initials: CC
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D017024:Chemotherapy, Adjuvant; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006258:Head and Neck Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008107:Liver Diseases / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D010437:Peptic Ulcer / Q000453:epidemiology; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D012042:Registries; D012189:Retrospective Studies; D000077195:Squamous Cell Carcinoma of Head and Neck; D015996:Survival Rate
keywords: Charlson comorbidity index score; Elixhauser comorbidity index score; Oral squamous cell carcinoma; Survival