ABSTRACT
Venous diseases including varicose veins and chronic venous insufficiency are one of the most important pathogenic factors worldwide. High prevalence of varicose veins and its complications is an emerging problem in the twenty-first century. This study aimed to determine the prevalence and associated risk factors of varicose veins in female hairdressers in Shahroud, north of Iran in 2012. In this cross-sectional study, 197 employed hairdressers, licensed by the Health Department of Shahroud University of Medical Sciences, Iran, were studied. Standard physical examination was used to check the condition of varicose veins of the lower extremities of participants. Data were collected by demographic information form. Proportional odds model for ordinal logistic regression was used to assess the relationship between risk factors and status of varicose disease in subjects. Prevalence of varicose veins was 47.7%. Varicose veins were significantly associated with age [OR=1.08; 95% CI: 1.03, 1.13]; family history of varicose disease [OR=1.99; 95% CI: 1.03, 3.82], blood pressure [OR=4.41; 95% CI: 1.63, 11.90]; and duration of standing [OR=2.34; 95% CI: 1.05, 5.22]. Varicose veins in the legs of female hairdressers had a high prevalence, and it was associated with increasing age, family history of varicose disease, high blood Pressure, and prolonged standing
ABSTRACT
The aim of this study is to evaluate the association between different treatments and survival time of breast cancer patients using either standard Cox model or stratified Cox model. The study was conducted on 15830 women diagnosed with breast cancer in British Columbia, Canada. They were divided into eight groups according to patients' ages and stage of disease Either Cox's PH model or stratified Cox model was fitted to each group according to the PH assumption and tested using Schoenfeld residuals. The data show that in the group of patients under age 50 years old and over age 50 with stage ? cancer, the highest hazard was related to radiotherapy [HR= 3.15, CI: 1.85-5.35] and chemotherapy [HR= 3, CI: 2.29- 3.93] respectively. For both groups of patients with stage ?? cancer, the highest risk was related to radiotherapy [HR=3.02, CI: 2.26-4.03] [HR=2.16, CI: 1.85-2.52]. For both groups of patients with stage III cancer, the highest risk was for surgery [HR=0.49, CI: 0.33-0.73], [HR=0.45, CI: 0.36-0.57]. For patients of age 50 years or less with stage IV cancer, none of the treatments were statistically significant. In group of patients over age 50 years old with stage ?V cancer, the highest hazard was related to surgery [HR=0.64, CI: 0.53-0.78]. The results of this study show that for patients with stage I and II breast cancer, radiotherapy and chemotherapy had the highest hazard; for patients with stage III and IV breast cancer, the highest hazard was associated with treatment surgery
ABSTRACT
The goal of this study is to extend the applications of parametric survival models so that they include cases in which accelerated failure time [AFT] assumption is not satisfied, and examine parametric and semiparametric models under different proportional hazards [PH] and AFT assumptions. The data for 12,531 women diagnosed with breast cancer in British Columbia, Canada, during 1990-1999 were divided into eight groups according to patients' ages and stage of disease, and each group was assumed to have different AFT and PH assumptions. For parametru: models, we fitted the saturated generalized gamma [GG] distribution/ and compared this with the conventional AFT model. Using a likelihood ratio statistic, both models were compared to the simpler forms including the Weibull and lognormal. For semiparametric models, either Cox's PH model or stratified Cox model was fitted according to the PH assumption and tested using Schoenfeld residuals. The GG family was compared to the log-logistic model using Akaike information criterion [AIC] and Baysian information criterion [BIC]. When PH and AFT assumptions were satisfied, semiparametric and parametric models both provided valid descriptions of breast cancer patient survival. When PH assumption was not satisfied but AFT condition held, the parametric models performed better than the stratified Cox model. When neither the PH nor the AFT assumptions were met, the log normal distribution provided a reasonable fit. When both the PH and AFT assumptions are satisfied, the parametric and semiparametric models provide complementary information. When PH assumption is not satisfied, the parametric models should be considered, whether the AFT assumption is met or not