The effects of multimedia education on postoperative delirium in patients undergoing coronary artery bypass graft: A randomized clinical trial.

BACKGROUND: Patients undergoing cardiac surgeries are at high risk of developing delirium. AIMS AND OBJECTIVES: The present study aimed to determine the effects of multimedia education on postoperative delirium in patients undergoing a coronary artery bypass graft. DESIGN: This study was a randomized clinical trial. METHODS: In this study, 110 patients undergoing a coronary artery bypass graft were assigned to two groups, control and intervention. Patients in the intervention group received multimedia education, and those in the control group received routine training. The inclusion criteria were experiencing the coronary artery bypass graft for the first time and non-development of post-operative cardiogenic shock or myocardial rupture. After measuring the level of consciousness, patients were examined in terms of delirium using the confusion assessment method for the ICU scale twice a day from admission to discharge from the ICU. The data were statistically analysed using χ2 test and Fisher's exact test. RESULTS: Patients of both groups were matched in terms of demographics. The highest incidence of delirium was observed on the first day after surgery in the intervention group (14.5%) and in the morning of the second day after surgery (29.1%) in the control group. Moreover, there was a significant difference between the two groups in the incidence of delirium in the morning of the second, third, and fourth days after surgery as it was higher in the control group over these days. CONCLUSION: Considering the lower incidence of post-operative delirium in patients who experienced multimedia education rather than control group, the use of this non-pharmaceutical method is recommended to prevent delirium in such patients. RELEVANCE TO CLINICAL PRACTICE: Delirium is also an acute organic brain syndrome that often leads to complicated conditions after cardiac surgeries. Fortunately, delirium is a preventable issue. The implementation of multimedia education as a non-pharmacological approach had positive effects on patients' delirium.

Determinants of survival of common childhood cancers in Iran.

BACKGROUND: Cancer is the second most common cause of morbidity and mortality in children. This study aimed to epidemiologically and demographically assess common cancers in children in Iran. MATERIALS AND METHODS: This cohort study was conducted on children registered in Mahak Hospital and Rehabilitation Complex (which is a non-governmental organizations (NGO)-related hospital for only malignant diseases). A total of 2232 questionnaires were filled out for cancer patients between 2007 and 2016. The factors including age, gender, race, family history, type of treatment, and type of cancer were entered into Cox regression model to examine their effect on mortality of children diagnosed with cancer. RESULTS: The Cox regression model showed that age, race, type of cancer, family history of cancer, and type of treatment had a significant effect on mortality of children diagnosed with cancer (P < 0.05). The hazard ratio (HR) of mortality in 10-15 years old was higher than that of 1-5 years old (P = 0.03, HR = 1.3). The HR of mortality in patients with brain tumor (P < 0.01, HR = 2.24), sarcoma (P < 0.01, HR = 2.32), and neuroblastoma (P < 0.01, HR = 2.56) was twice the value in patients with leukemia. The HR of mortality in patients who had a family history of cancer was higher than that of patients without it (P < 0.01, HR = 1.33). Patients who had undergone chemotherapy along with surgery and radiotherapy (P = 0.02, HR = 0.68) and patients who received chemotherapy along with surgery (P = 0.01, HR = 0.67) had a lower HR of mortality compared to the chemotherapy group. CONCLUSION: Young age, multidisciplinary approach, and absence of family history were associated with lower hazard of death in children diagnosed with cancer; brain tumor, leukemia, and sarcoma had higher hazard of mortality compared to leukemia. Children with a family history of cancer should be under regular follow-up. Treatment should be multidisciplinary and comprehensive.

Relationship between anxiety and quality of life in the presence of other factors in adult celiac patients; a nationwide study.

Aim: This study aimed to detect relationships among quality of life (QoL) and anxiety and demographic factors in patients with celiac disease (CD). Background: CD is a type of autoimmune small intestine diseases caused by gluten ingestion. In Iran, the prevalence of CD is considered to be 1% in the general population. As physical problems and behavioral disorders of CD can lead to a reduction in QoL. Methods: This cross-sectional study was performed on 533 patients with Celiac Disease from 9 cities of Iran. Data collected were analyzed by SPSS version 22. Quality of life and anxiety respectively evaluated by (GHQ-28) and SAS questionnaires. Predictors of quality of life (sex, age, age of diagnosis, city of life, education level, family history of celiac, occupation and anxiety) were tested by multiple linear regression. Results: Our results showed a significant relationship between poor quality of life and anxiety (correlation= -0.143, P=0.001). The mean of the quality of life index in celiac diseases was 126.2±30.4 and women had a lower quality of life than men (P=0.003) importantly in emotions and worries scores. There was no significant difference between male and female in terms of anxiety level. Conclusion: According to the results, both quality of life and anxiety correlated together and women seem to suffer more than men from celiac disease. Therefore, greater attention to women who have celiac disease are suggested.

An Investigation into the Effects of Omega-3 on Uremic Pruritus in Hemodialysis Patients: A Randomized Crossover Clinical Trial.

Itching along with other problems can be one of the factors exacerbating the sufferings and disturbing the comfort of patients with chronic renal failure. The present research aimed to study the effects of omega-3 on the treatment of uremic pruritus in hemodialysis (HD) patients. In this crossover randomized clinical trial study, 52 HD patients with pruritus were evaluated. After the random assignment of the participants to Group 1 (treatment mode A) (omega-3 plus cetirizine) and Group 2 (treatment mode B) (cetirizine), they received the treatments for six weeks and then after one week washout period, treatments were changed between the two groups. The pruritus severity was measured using the Yosipovitch pruritus questionnaire before the intervention and at the end of each treatment period. The obtained data were analyzed using descriptive statistics, analysis of variance with repeated measures, and Pearson correlation coefficient. The results of this study showed that pruritus severity reduced in both groups, but it was more significant in Group 1 (omega-3 plus cetirizine). The study findings indicated that omega-3 is effective in the reduction of uremic pruritus. Therefore, this supplement can be used as a convenient method for reducing pruritus in HD patients.

Survival to intensive care unit discharge among in-hospital cardiac arrest patients by applying audiovisual feedback device.

AIMS: Survival rates after in-hospital cardiac arrest remain very low. Although there is evidence that the use of audiovisual feedback devices can improve compression components, there are no data on patient survival. Therefore, we conducted this study to analyse the survival rate of patients with in-hospital cardiac arrest after discharge from the intensive care unit. METHODS AND RESULTS: This study was a secondary analysis of a prospective, randomized, controlled, parallel study of patients who received either standard manual chest compression or a real-time feedback device. Parametric and semi-parametric models were fitted to the data. Different survival time of length of stay was investigated by univariate and multiple analyses. Pearson's correlation between length of stay and hospital length of stay was obtained. A total of 900 patients with a mean survival time of 35 days were included. Intervention was associated with a higher length of stay. Relative time was significant in adjusted fitted log-normal regression for intervention group, female gender, and cardiopulmonary resuscitation in the night shift. A positive correlation between length of stay and hospital length of stay was found. CONCLUSIONS: Implementation of feedback device improved survival and length of stay. Cardiopulmonary resuscitation performance during the night shift decreased the survival time, which could be due to the inexperienced staff available outside working hours.

The effects of omega-3 on the sleep quality of patients with uremic pruritus undergoing hemodialysis: a randomized crossover study.

OBJECTIVES: Information on sleep quality and its effective factors in the patients undergoing hemodialysis are important factors in future planning for improving sleep quality and ultimately the quality of life in these patients. The present study investigated the effect of omega-3 on the sleep quality of hemodialysis patients. METHODS: The 52 hemodialysis patients were randomized into two groups and underwent two different treatment modes (A and B). The first group was given omega-3 and cetirizine and the second group only received cetirizine for six weeks. After one week wash out, the study was followed by crossover treatment in both groups for six weeks. Sleep quality and pruritus severity were evaluated in patients before the intervention and at the end of each treatment period using the Pittsburgh Sleep Quality Index and the Yosipovitch Itch Questionnaire. The collected data was analyzed using repeated measures ANOVA and the Pearson correlation coefficient. RESULTS: The results of the study showed that majority of the patients (94.2%) had poor sleep quality (sleep score > 5 based on the questionnaire) and 5.8% of the patients had favorable sleep quality (sleep score < 5). Repeated measures ANOVA showed that sleep quality scores were different in two groups in phases 0, I and II (p <0.001). CONCLUSIONS: Sleep quality improved in both modes but more improvement was observed in mode A. Therefore, omega-3 fatty acids can be used as a suitable method for improving sleep quality in hemodialysis patients.

Comparing the effects of cold compress and Xyla-p cream on hemodynamic changes in hemodialysis patients during venipuncture.

Background The vital signs reflect the physiological state of patients in various clinical conditions. The purpose of this study was to compare the effects of cold compress and Xyla-P cream on hemodynamical changes during venipuncture in hemodialysis patients. Methods and Material In this clinical trial study, 50 patients under hemodialysis were selected by simple random sampling. The patients were then randomly assigned to either Xyla-P cream, cold compress or placebo groups. The vital signs (blood pressure and pulse) were measured upon two intermittent hemodialysis sessions before and after venipuncture. Data were analyzed using repeated measures analysis of variance. Results The mean alternation in systolic blood pressure was significantly different comparing the placebo and cold compress groups before and after intervention (p<0.001). However, the difference was not significant between the Xyla-P cream group and either placebo (p=0.402) or ice compress (p=0.698) groups. The difference of the mean diastolic blood pressure was significant comparing the placebo group with either the Xyla-P cream group (p=0.003) or cold compress group (p<0.001) before and after intervention. In addition, there was a significant difference in the mean number of heartbeats comparing the control group with either the Xyla-P cream group (p<0.001) or cold compress group (p<0.001) before and after the intervention. Conclusions Considering the beneficial effects of ice compress and the Xyla-P cream on reduction of cardiovascular parameters, it is recommended to use these methods in hemodialysis patients during venipuncture.

Mixture cure model for estimating short-term and long-term colorectal cancer survival.

AIM: We used mixture cure mode to separately investigate the risk factors for long-term and short-term survival of colorectal cancer patients. BACKGROUND: Colorectal cancer (CRC) is the second most common cancer worldwide. In cancer studies, patients' survival is the most important indicator of patients' status. Classical methods in analyzing the survival data usually apply Cox proportional hazard regression. METHODS: The study was performed on 1121 patients diagnosed with colorectal cancer. Mixture cure model with Weibull distribution and logit link function was fitted to data. RESULTS: Odds of long-term survival for rectum cancer patients were lower than for colon cancer patients (OR=0.29(0.09, 0.9)). Also, patients with the advanced stage of the disease had lower odds of long-term survival compared to early-stage patients (OR=0.24(0.06, 0.86)).In the short-term, the hazard of death for people with normal BMI was lower than the underweight group (HR=0.4(0.21, 0.76)). The short-term hazard of death for rectum cancer was about half of the short-term hazard for colon cancer (HR=0.49(0.29, 0.81)). Further, people with moderately (HR=2.11(1.26, 3.55)) and poorly (HR=4.04(2.03, 8.03)) differentiated tumor grade had a higher short-term hazard of death compared to people with well-differentiated grade. CONCLUSION: Predictive variables of colorectal cancer survival showed different effects in short- and long -terms. Site topography was a prognosis for both long-term and short-term survival; BMI and tumor grade were short-term predictors of survival while stage was a long-term predictor of survival.

Assessment of the fitness of Cox and parametric regression models of survival distribution for Iranian breast cancer patients' data.

Factors affecting the time of survival after breast cancer (BC) diagnosis remain unknown. However, some of the prognostic factors have been identified. The aim of this study was to investigate the effects of biologic and socioeconomic factors on long-term survival of BC patients. This was a descriptive chart review and survey of all women with a confirmed diagnosis of BC registered in Shohada-e-Tajrish Cancer Research Center database from March 2004 to March 2015. The checklist of study consisted of biologic, demographic, reproductive, genetic, medical, and therapeutic information of patients. The minimum time of follow-up was 3 years and the maximum was 10 years. We then evaluated possible associations of these variables with BC survival using Cox and parametric regression models of survival analysis. The study population was 1276 BC patients. Their mean survival was 23 (range 1-120) months. Between the parametric models, Weibull regression model demonstrated the lowest Akaike information criterion and thus the best fit, and tumor size, number of lymph nodes, BC stage, educational level, and high-fat diet were significant in this model. Based on our findings, educational level, consumption of fat, and characteristics of tumor at the time of diagnosis (disease stage, tumor size, number of involved lymph nodes) are the most important prognostic factors affecting long-term survival of BC patients. We suggest that future studies assess the efficacy of possible interventions for these factors.

Evaluation and comparison of the effects of Xyla-P cream and cold compress on the pain caused by the cannulation of arteriovenous fistula in hemodialysis patients.

This study aimed to investigate and compare the effects of Xyla-P cream and cold compress on the pain caused by the insertion of a needle into the arteriovenous fistula (AVF) in hemodialysis (HD) patients. This clinical trial was conducted on HD patients who were selected using simple random sampling method. Using a visual analog scale, pain intensity was measured during two HD sessions in three stages including after the application of a placebo, after application of Xyla-P cream, and after the application of cold compress. The collected data were analyzed using descriptive statistics and repeated measures analysis of variance. Our results showed that there were statistically significant differences between the pain scores of the control group and Xyla-P cream group (P <0.001) and cold compress group (P <0.001) and between the pain scores of the Xyla-P cream group and cold compress group (P <0.001). The cannulation of an AVF causes moderate pain in HD patients. Cold compress is more effective than Xyla-P cream in reducing the intensity of the pain. Therefore, the nurses are recommended to use this pain relief method instead of medicinal methods.

Self-medication and its risk factors among women before and during pregnancy.

INTRODUCTION: Self-medication can cause significant challenges for the individuals and community, especially in women during pregnancy. This study was aimed to compare the prevalence of self-medication before and during pregnancy among women in Iran. METHODS: in this cross-sectional study, a total of 384 pregnant women were evaluated for the prevalence of self-medication and its associated factors before and during pregnancy. Stratified random sampling was used as the sampling method. Descriptive statistics and chi-square and logistic regression tests were used for statistical analysis of data. RESULTS: The results showed that the prevalence of self-medication, in women who had become ill at least once, was 63.9% before pregnancy and 43.5% and during pregnancy. Variables such as lack of insurance, high school education and not having a child increased odds ratio of self-medication before pregnancy, while the variables of lack of insurance, not having a child or fewer number of children and no history of abortion increased the odds ratio of self-medication during pregnancy. CONCLUSION: Although the prevalence of self-medication during pregnancy was less than that before pregnancy, but this prevalence during pregnancy was still significant. Therefore, it seems necessary to provide public trainings for all women of reproductive age and train them about the dangers and side effects of self-medication.

Relationship of Social Determinants of Health with the Three-year Survival Rate of Breast Cancer

Background: Social determinants of health are among the key factors affecting the pathogenesis of diseases. Considering the increasingly high prevalence of breast cancer and the association of social determinants of health with its occurrence, related morbidity and mortality and survival rate, this study sought to assess the relationship of three-year survival rate of breast cancer with social determinants of health. Materials and Methods: This cohort study was conducted on males and females presenting to the Cancer Research Center of Shohada-E-Tajrish Hospital from 2006 to 2010 with definite diagnosis of breast cancer. Data were collected via phone interviews. Kaplan-Meier and Cox regression was fitted using SPSS (version 18) and PH assumption was tested by STATA (version 11) software. Results: The study was performed on 797 breast cancer patients, aged 25-93 years with mean age of 54.66 (SD=11.86) years. After 3 years from diagnosing cancer 700 (87.8%) patients were alive and 97 (12.2%) patients were dead. Using log rank test, there was relationship between 3-year survivals with age, education, childhood residence, sibling, treatment type, and district were significant (p<0.05). Using Cox PH regression, 3-year survival was related to age, level of education, municipal district of residence and childhood condition (p<0.05). Conclusion: Social determinants of health such as childhood condition, city region residency, level of education and age affect the three-year survival rate of breast cancer. Future studies must focus on the effect of childhood social class on the survival rates of cancers, which have been paid less attention to.

Influence of nutritional education on hemodialysis patients' knowledge and quality of life.

To determine the effects of educational instructions on hemodialysis patients' knowledge and quality of life (QOL), we studied 99 patients randomly assigned to control and experimental groups after participation in a pretest exam. The two groups were not significantly different in terms of demographic composition. The instrument used in this study was a questionnaire regarding patients' knowledge and the standard questionnaire to assess QOL for end-stage renal disease (ESRD) patients. Then, intervention (nutritional education) was conducted in the experimental group lasting for 12 weeks. After 16 weeks, a post test regarding subjects' knowledge on dietary instructions and their QOL were as conducted. There was no significant difference in QOL score and knowledge score before and after intervention in the control group, but there was a significant difference in the experimental group. In addition, after the intervention, the difference in knowledge and QOL score persisted between the two groups. The results of this study supported the positive effects of educational program on patients' knowledge and QOL among ESRD patients. It is recommended that dietary instruction be included in all educational programs to improve ESRD patients' QOL.

Evaluation of empowerment model on indicators of metabolic control in patients with type 2 diabetes, a randomized clinical trial study.

AIMS: Diabetes education is a major subject in achieving optimal glycemic control. Effective empowerment approach can be beneficial for improving patients' health. The aim of this study was to evaluate the effect of empowerment model on indicators of metabolic control in patients with type 2 diabetes. METHODS: a randomized controlled trial of 103 patients with type 2 diabetes were randomly assigned to either the intervention (empowerment approach training) or the control group (conventional training) 2014. Empowerment approach training were performed for the experimental group for eight weeks. Data collection tool included demographic information form and indicators of metabolic control checklist. Analysis was performed by one-way analysis of variance, chi-square test, paired t-test, independent t-test and multiple linear regression. RESULTS: Before the intervention, two groups were homogeneous in terms of demographic variables, glycosylated hemoglobin (HbA1C), and other indicators of metabolic control. After the intervention, average HbA1C and other metabolic indicators except for LDL showed significant differences in the experimental group compared to the control group. CONCLUSION: study results indicated the positive effects of applying the empowerment model on the metabolic control indicators. Therefore, applying this model is recommended to nurses and the relevant authorities in order to improve clinical outcomes in diabetic patients.

Application of Cox and Parametric Survival Models to Assess Social Determinants of Health Affecting Three-Year Survival of Breast Cancer Patients.

Breast cancer is one of the most common causes of cancer mortality in Iran. Social determinants of health are among the key factors affecting the pathogenesis of diseases. This cross-sectional study aimed to determine the social determinants of breast cancer survival time with parametric and semi-parametric regression models. It was conducted on male and female patients diagnosed with breast cancer presenting to the Cancer Research Center of Shohada-E-Tajrish Hospital from 2006 to 2010. The Cox proportional hazard model and parametric models including the Weibull, log normal and log-logistic models were applied to determine the social determinants of survival time of breast cancer patients. The Akaike information criterion (AIC) was used to assess the best fit. Statistical analysis was performed with STATA (version 11) software. This study was performed on 797 breast cancer patients, aged 25-93 years with a mean age of 54.7 (±11.9) years. In both semi-parametric and parametric models, the three-year survival was related to level of education and municipal district of residence (P<0.05). The AIC suggested that log normal distribution was the best fit for the three-year survival time of breast cancer patients. Social determinants of health such as level of education and municipal district of residence affect the survival of breast cancer cases. Future studies must focus on the effect of childhood social class on the survival times of cancers, which have hitherto only been paid limited attention.

Prevalence and risk factors of varicose veins among female hairdressers: a cross sectional study in north-east of Iran.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Cox models survival analysis based on breast cancer treatments.

BACKGROUND: 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. METHODS: 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. RESULTS: The data show that in the group of patients under age 50 years old and over age 50 with stage I 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 II 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 IV cancer, the highest hazard was related to surgery (HR=0.64, CI: 0.53-0.78). CONCLUSION: 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.

Social determinants of health and 5-year survival of colorectal cancer.

BACKGROUND: Early in the 21st century, cancers are the second cause of death worldwide. Colon cancer is third most common cancer and one of the few amenable to early diagnosis and treatment. Evaluation of factors affecting this cancer is important to increase survival time. Some of these factors affecting all diseases including cancer are social determinants of health. According to the importance of this disease and relation with these factors, this study was conducted to assess the relationship between social determinants of health and colon cancer survival. MATERIALS AND METHODS: This was a cross-sectional, descriptive study for patients with colon cancer registered in the Cancer Research Center of Shahid Beheshti University of Medical Science, from April 2005 to November 2006, performed using questionnaires filled by telephone interview with patients (if patients had died, with family members). Data was analyzed with SPSS software (version 19) for descriptive analysis and STATA software for survival analysis including log rank test and three step Cox Proportional Hazard regression. RESULTS: Five hundred fifty nine patients with ages ranging from 23 to 88 years with mean ± standard deviation of 63 ± 11.8 years were included in the study. The five year survival was 68.3%( 387 patients were alive and 172 patients were dead by the end of the study). The Cox proportional hazard regression showed 5-year survival was related to age (HR=0.53, p=0.042 for>50 years versus<50 years old) in first step, gender (HR=0.60, p=0.006 for female versus male) in second step, job (HR=1.7, p=0.001 for manual versus non manual jobs), region of residency (HR=3.49, p=0.018 for west versus south regions), parents in childhood (HR=2.87, p=0.012 for having both parents versus not having), anatomical cancer location (HR=2.16, p<0.033 for colon versus rectal cancer) and complete treatment (HR=5.96, p<0.001 for incomplete versus complete treatment). CONCLUSIONS: Social determinants of health such as job, city region residency and having parents during childhood have significant effects in 5-year survival of colon cancer and it may be better to consider these factors in addition to developing cancer treatment and to focus on these determinants of health in long-time planning.

Applying conventional and saturated generalized gamma distributions in parametric survival analysis of breast cancer.

BACKGROUND: The generalized gamma distribution statistics constitute an extensive family that contains nearly all of the most commonly used distributions including the exponential, Weibull and log normal. A saturated version of the model allows covariates having effects through all the parameters of survival time distribution. Accelerated failure-time models assume that only one parameter of the distribution depends on the covariates. METHODS: We fitted both the conventional GG model and the saturated form for each of its members including the Weibull and lognormal distribution; and compared them using likelihood ratios. To compare the selected parameter distribution with log logistic distribution which is a famous distribution in survival analysis that is not included in generalized gamma family, we used the Akaike information criterion (AIC; r=l(b)-2p). All models were fitted using data for 369 women age 50 years or more, diagnosed with stage IV breast cancer in BC during 1990-1999 and followed to 2010. RESULTS: In both conventional and saturated parametric models, the lognormal was the best candidate among the GG family members; also, the lognormal fitted better than log-logistic distribution. By the conventional GG model, the variables "surgery", "radiotherapy", "hormone therapy", "erposneg" and interaction between "hormone therapy" and "erposneg"are significant. In the AFT model, we estimated the relative time for these variables. By the saturated GG model, similar significant variables are selected. Estimating the relative times in different percentiles of extended model illustrate the pattern in which the relative survival time change during the time. CONCLUSIONS: The advantage of using the generalized gamma distribution is that it facilitates estimating a model with improved fit over the standard Weibull or log- normal distributions. Alternatively, the generalized F family of distributions might be considered, of which the generalized gamma distribution is a member and also includes the commonly used log-logistic distribution.

Breast Cancer Survival Analysis: Applying the Generalized Gamma Distribution under Different Conditions of the Proportional Hazards and Accelerated Failure Time Assumptions.

BACKGROUND: 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. METHODS: 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 parametric 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). RESULTS: 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. CONCLUSIONS: 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.