Comparison of different comorbidity measures for oral cancer patients with surgical intervention: A longitudinal study from a single cancer center.

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.