Comparison of case-deletion diagnostic methods for Cox regression.

Case-deletion diagnostics are a routine component of regression analysis since they identify unusual observations that substantially affect parameter estimates. The exact approach is to compute the change in each regression parameter by dropping that individual and refitting the model. Repeating a Cox regression for the removal of each individual is very time consuming and therefore not done in practice.

Univariate and multivariate analysis of prognostic significance of betel quid chewing in squamous cell carcinoma of buccal mucosa in Taiwan.

Background And Objectives: While betel quid (BQ) chewing is clearly the most avoidable risk factor of squamous cell carcinoma of buccal mucosa (BMSCC), little is known about the influence of this habit on the prognosis of BMSCC.

Methods: We surveyed 280 patients with BMSCC who were treated during an 8-year period in a cohort study to assess the independent predictive value of pretreatment BQ chewing habit on the prognosis by univariate and multivariate analysis.

Results: We found by univariate analysis that sex, age, clinical stage, smoking, and BQ chewing significantly affected the patients' prognosis and only age, clinical stage, and BQ chewing had significant influence on prognosis by multivariate analysis (P < 0.