ABSTRACT
Although the Cox proportional hazard regression is the most popular model for analyzing the prognostic factors on survival of cancer patients, under certain circumstances, parametric models estimate the parameter more efficiently than the Cox model. The aim of this study was to compare the Cox regression model with parametric models in patients with gastric cancer who registered at Taleghani hospital, Tehran, Iran. In a retrospective cohort study, 746 patients with gastric cancer were studied from February 2003 through January 2007. Gender, age at diagnosis, distant metastasis, extent of wall penetration, tumor size, histology type, tumor grade, lymph node metastasis and pathologic stage were selected as prognosis, and entered to the models. Lognormal, Exponential, Gompertz, Weibull, Loglogistic and Gamma regression were performed as parametric models, and Akaike Information Criterion [AIC] were used to compare the efficiency of the models. Based on AIC, Log logistic is an efficient model. Log logistic analysis indicated that wall penetration and presence of pathologic distant metastasis were potential risks for death in full and final model analyses. In the multivariate analysis, all the parametric models fit better than Cox with respect to AIC; and the log logistic regression was the best model among them. Therefore, when the proportional hazard assumption does not hold, these models could be used as an alternative and could lead to acceptable conclusions
Subject(s)
Humans , Male , Female , Aged, 80 and over , Adult , Middle Aged , Aged , Models, Statistical , Stomach Neoplasms , Retrospective Studies , Cohort StudiesABSTRACT
Midazolam is preferably used in pediatric dentistry for quick onset of action and recovery. The aim of this prospective, observer-blind and placebo-controlled study was to assess the efficacy of a low dose of oral midazolam in modification of the behavior of young pediatric dental patients. Forty children aged 3 to 5 years who displayed ratings 1 or 2 on the Frankl Scale and were healthy by the American Society of Anesthesiologists-I status were randomly divided into two experimental and control groups of 20 each. All children required pulpotomy and restoration of D and E teeth and received either 0.25mg/kg of a 15mg/3ml IV midazolam mixed in black cherry syrup or the syrup alone. Subjects were continuously observed and monitored with pulse oximetry. Houpt's Behavioral Ratings was used to determine the overall behavior, the degree of crying and movement during treatment. Mann-Whitney U test was used for statistical analysis. Patients who received 0.25mg/kg of the prepared oral midazolam significantly behaved better during treatment than the placebo controls [P<0.05]. In comparison with the placebo group, reduced movement and crying were observed in the midazolam group [P<0.05]. No adverse effects were observed and treatments were completed successfully. A low dose of 0.25mg/kg of a 15mg/3ml IV midazolam mixed in black cherry syrup was found to be effective in conscious sedation of young pediatric dental patients