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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Kerman University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: dialysis,End Stage Renal Disease,Random Survival Forest Model,Events per Variable
- چکیده:
- چکیده انگلیسی: Background:Dialysis is a process for eliminating extra uremic fluids of patients with chronic renal failure. The present study aimed to determine the variables that influence the survival of dialysis patients using random survival forest model (RSFM) in low-dimensional data with low events per variable (EPV).
Methods:In this historical cohort study, information was collected from 252 dialysis patients in Bandar Abbas hospitals, Iran. The survival time of the patients was calculated in years from the onset of dialysis to death or until the end of the study in 2016. RSFM was used as the number of events per variable (EPV) was low. The data collected from 252 patients were randomly divided into training and testing sets, and this process was repeated 100 times. C-index and Brier Score (BS) were used to assess the performance of the model in the test set.
Results: In this study, 35 (13.9%) mortality cases were observed. Based on the findings, the mean C-index value in training and testing sets was 0.640 and 0.687, and the mean BS value in training and testing sets was 0.017 and 0.023, respectively. The results of the RSFM revealed that BMI, education, occupation, dialysis duration, number of dialysis sessions and age at dialysis onset were the most important factors.
Conclusion: RSFM can be used to determine the survival of dialysis patients and manage low-dimensional data with few-events if the researcher desires to select a nonparametric model.- انتشار مقاله: 11-04-1398
- نویسندگان: Shideh Rafati,Mohammad Reza Baneshi,Laleh Hassani,Abbas Bahrampour
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Kerman University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Multi-collinearity,High dimension,Penalized regression,Lasso
- چکیده:
- چکیده انگلیسی: Background: Two main issues that challenge model building are number of Events Per Variable and multicollinearity among exploratory variables. Our aim is to review statistical methods that tackle these issues with emphasize on penalized Lasso regression model. The present study aimed to explain problems of traditional regressions due to small sample size and multi-colinearity in trauma and influenza data and to introduce Lasso regression as the most modern shrinkage method.
Methods: Two data sets, corresponded to Events Per Variable of 1.5 and 3.4, were used. The outcomes of these two data sets were hospitalization due to trauma and hospitalization of patients suffering influenza respectively. In total, four models were developed: classic Cox and logistic regression models, as well as their penalized lasso form. The tuning parameters were selected through 10-fold cross validation.
Results: Traditional Cox model was not able to detect significance of any of variables. Lasso Cox model revealed significance of respiratory rate, focused assessment with sonography in trauma, difference between blood sugar on admission and 3 h after admission, and international normalized ratio. In the second data set, while lasso logistic selected four variables as being significant, classic logistic was able to identify only the importance of one variable.
Conclusion: The AIC for lasso models was lower than that for traditional regression models. Lasso method has practical appeal when Events Per Variable is low and multicollinearity exists in the data.
- انتشار مقاله: 08-02-1398
- نویسندگان: Abolfazl Hosseinnataj,Abbas Bahrampour,Mohammadreza Baneshi,Farzaneh Zolala,Roya Nikbakht,Mehdi Torabi,Fereshteh Mazidi Sharaf Abadi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Kerman University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: risk stratification,hemodialysis,Hand Grip Strength,Malnutrition-Inflammation Score,Protein- Energy Wasting
- چکیده:
- چکیده انگلیسی: Background: We aimed to detect whether risk stratification of hemodialysis (HD) patients with a combination of both malnutrition-inflammation score (MIS) and hand grip strength (HGS) indices identified more precisely patients at increased risk of protein-energy wasting (PEW). Methods: This was a deductive-analytical cross-sectional study. We determined the HGS and MIS of 83 HD patients who were randomly selected from the dialysis centers in Kerman. Data were analyzed using t-tests and One-way ANOVA. Multinomial logistic regression and receiver operating characteristic (ROC) curve analysis were performed accordingly. Results: There were significant differences between normal and high risk MIS regarding gender, having diabetes mellitus (DM), duration of dialysis, serum albumin, and C-reactive protein (P= 0.021, 0.049, 0.003, 0.038, and 0.027, respectively). There were also significant differences between normal and high risk HGS groups regarding age, having DM, cause of kidney disease (DM and/or hypertension), creatinine level, total cholesterol, weight, height, and mid upper arm circumference (P= 0.000, 0.006, 0.024, 0.011, 0.044, 0.026, 0.014, and 0.029, respectively). The ROC curves of the MIS and HGS indices showed sensitivity and specificity of 89.7% and 93.8%; 78.0% and 72.5%; respectively. Conclusions: Our findings reveal that patients, defined as “normal by both”, “normal by either”, and/or “high risk by both” based on the diagnostic tools, exhibit different markers compared to patients categorized by either index separately. The cutoff of MIS for the occurrence of PEW varied depending on the procedure used. The sensitivity and specificity of MIS and HGS indices were excellent.
- انتشار مقاله: 10-04-1397
- نویسندگان: Mohammad Reza Mahmoodi,Naser Hasheminejad,Abbas Bahrampour,Jalal Azmandian,Mina Namdari
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Kerman University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Metastasis,acute myeloid leukemia,Leukemia,Acute Lymphoblastic Leukemia,Phase-type Distribution,EM Algorithm,Transitional Phase,Absorption Phase,Death or Recovery probability
- چکیده:
- چکیده انگلیسی: Background: In this study, with the aim of modeling Leukemia in children using Phase-type distribution, three transitional phases including diagnosis, brain metastasis and testis/ovary metastasis, and one absorotion phase of recovery/death have been considered. The distribution was fitted and the probabilities of death or recovery were determined based on the independent variables including age, sex, blood group, etc. Methods: In this modeling study, necessary information was extracted from patients’ medical records (recorded during 2006-2013) available in the Medical Records Department of Afzalipour Hospital of Kerman/ Iran. After excluding the unrelated cases, Phase-type distribution was fitted in which four phases including three transitional phases (cancer diagnosis, brain metastasis, and testis/ ovary metastasis ) and one absorption phase (death or recovery) have been considered. For this purpose, different modeling methods were used for patients who had died and recovered. EM algorithm was used for modeling and fitting Phase-type distribution. Data were analyzed using SPSS22 and R. After fitting Phase-type distribution and determining the probabilities of absorption, the effect of each independent variable on these probabilities was evaluated, and t-test, Pearson’s correlation coefficient, and One-way analysis of variance (ANOVA) were used for the analysis of different variables. Results: The variables of sex and the presence or absence of splenomegaly and hepatomegaly had no effect on the probability of death and recovery. However, the probability of death showed significant relationship (p<0.0001) with the diagnosis of cancer type (ALL or AML) and it was more in patients diagnosed with ALL. Death probability had also significant relationship with brain and testis/ovary metastasis (P=0.002). As expected, the probability of death in patients with brain or testis/ovary metastasis compared to those without matastasis was more. In addition, the p-value of the test used to assess the association between the probability of death and blood groups was 0.025; therefore, there is a significant difference in the probability of death between at least two blood groups. Conclusion: The results show that the diagnosis of cancer type and treatment method can affect the probabilities of death and recovery. Further studies on other variables can help physicians to predict the probabilities of death or recovery during the development of cancer and choose the best treatment method to enhance the probability of recovery in these patients.
- انتشار مقاله: 06-02-1394
- نویسندگان: Marzieh Mahmoudimanesh,Abbas Bahrampour,Zahra Farahmandinia
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Otorhinolaryngology
- نوع مقاله: Journal Article
- کلمات کلیدی: Noise Induced Hearing Loss,Linear Mixed Model,Longitudinal Studies
- چکیده:
- چکیده انگلیسی: Introduction:
Noise is one of the most common and harmful physical factors in the working environment and has physical and psychological effects on individuals. In this study, the audiometry results of industrial workers were modeled and the effect of noise and other factors on hearing loss was examined.
Materials and Methods:
This was a longitudinal study based on the records of workers who had worked over 10 years in the industry and had recorded audiometries since their employment. Data was analyzed through linear mixed models.
Results:
During each year of noise exposure, hearing loss was 1.9 db at 4000 Hz; 0.059 in low frequencies and 0.62 db in high frequencies. At 8000 Hz the effect of the age at employment on hearing loss was significant (P=0.014). At low frequencies the interaction of smoking and age at employment was significantly related to hearing loss (P˂0.001).
Conclusion:
This study showed that despite acquaintance with safety measures, workers still face hearing loss in industry and employers should put workers under more surveillance for using protective gear. Smoking might be another risk factor for hearing loss.- انتشار مقاله: 30-10-1397
- نویسندگان: Fatemeh Khaldari,Narges Khanjani,Abbas Bahrampour,Mohammad Reza Ghotbi Ravandi,Aliasghar Arabi Mianroodi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: risk factors,diabetes,Metabolic Syndrome,Type 2
- چکیده:
- چکیده انگلیسی: Metabolic syndrome is highly prevalent in type 2 diabetics and is a strong risk factor for cardiovascular diseases in such patients. The aim of this study was to determine the prevalence of metabolic syndrome according to the three criteria of ATPIII, IDF and the new criteria for metabolic syndrome diagnosis in Kerman, Iran.This cross-sectional study was performed on 950 diabetic type 2 patients. Data was analyzed by independent t-test, chi-square and logistic regression using the SPSS (revision 20) software.The prevalence of metabolic syndrome in Kerman was 73.4, 64.9, and 70.4%, according to the above criteria. Fasting blood sugar, gender, triglyceride, HDL, waist circumference, and systolic blood pressure were related to the prevalence of metabolic syndrome according to the above-mentioned criteria.The prevalence of metabolic syndrome is high in type 2 diabetic patients and the above-mentioned factors exacerbate the situation
- انتشار مقاله: 28-11-1392
- نویسندگان: Zohre Foroozanfar,Hamid Najafipour,Narges Khanjani,Abbas Bahrampour,Hosseinali Ebrahimi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Health Policy and Management
- نوع مقاله: Journal Article
- کلمات کلیدی: Iran,seasonality,Tuberculosis (TB),Migrant
- چکیده:
- چکیده انگلیسی: Background
There are few quantitative documents about the seasonal incidence of tuberculosis (TB) among immigrant populations. Concerning the significant role of recognizing seasonal changes of TB in improving the TB control program, this study determines the trend and seasonal temporal changes of TB among immigrants entering Iran.
Methods
In this longitudinal study, data from the Iranian TB register Program (from 2005 to 2011) was used. The aggregated number of monthly and seasonal TB cases was obtained by adding the daily counts. Data was analyzed by Chi-square, Independent T-test, ANOVA, and Poisson regression using Stata 11 and SPSS 20 software.
Results
Among 74,155 registered patients with TB, 14.3% (10,587) were non-Iranian who had immigrated to Iran from 29 different countries. The highest aggregated number of seasonal and monthly incidence of TB in immigrants was observed in spring (2824, P= 0.007) and in May (1037, P< 0.001). The number of non-Iranian patients with TB increased significantly over the years (β= 0.016, P= 0.001).
Conclusion
This study shows that immigrants constitute a significant portion of TB patients recorded in Iran and this trend is increasing. Also, the peak incidence of this disease is the second month of the spring.- انتشار مقاله: 14-01-1393
- نویسندگان: Mahmood Moosazadeh,Narges Khanjani,Abbas Bahrampour,Mahshid Nasehi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Health Policy and Management
- نوع مقاله: Journal Article
- کلمات کلیدی: Time series,Assessment,Trend,seasonality,Road Accident
- چکیده:
- چکیده انگلیسی: Background
Road traffic accidents and their related deaths have become a major concern, particularly in developing countries. Iran has adopted a series of policies and interventions to control the high number of accidents occurring over the past few years. In this study we used a time series model to understand the trend of accidents, and ascertain the viability of applying ARIMA models on data from Taybad city.
Methods
This study is a cross-sectional study. We used data from accidents occurring in Taybad between 2007 and 2011. We obtained the data from the Ministry of Health (MOH) and used the time series method with a time lag of one month. After plotting the trend, non stationary data in mean and variance were removed using Box-Cox transformation and a differencing method respectively. The ACF and PACF plots were used to control the stationary situation.
Results
The traffic accidents in our study had an increasing trend over the five years of study. Based on ACF and PACF plots gained after applying Box-Cox transformation and differencing, data did not fit to a time series model. Therefore, neither ARIMA model nor seasonality were observed.
Conclusion
Traffic accidents in Taybad have an upward trend. In addition, we expected either the AR model, MA model or ARIMA model to have a seasonal trend, yet this was not observed in this analysis. Several reasons may have contributed to this situation, such as uncertainty of the quality of data, weather changes, and behavioural factors that are not taken into account by time series analysis.- انتشار مقاله: 23-01-1392
- نویسندگان: Alireza Razzaghi,Abbas Bahrampour,Mohammad Reza Baneshi,Farzaneh Zolala
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Pacific Journal of Cancer Prevention
- نوع مقاله: Journal Article
- کلمات کلیدی: Breast cancer,Survival,Cure models,Bayesian
- چکیده:
- چکیده انگلیسی: Background: Breast cancer is a top biomedical research priority, and it is a major health problem. Therefore, the present study aimed to determine the prognostic factors of breast cancer survival using cure models. Methods: In this retrospective cohort analytic study, data of 140 breast cancer patients were collected from Ali Ibn Abi Taleb hospital, Rafsanjan, Southeastern Iran. Since in this study, a part of the population had long-term survival, cure models were used and evaluated using DIC index. The data were analyzed using Openbugs Software. Results: In this study, of 140 breast cancer patients, 23 (16.4%) cases died of breast cancer. Based on the findings, the Bayesian nonmixture cure model, with type I Dagum distribution, was the best fitted model. The variables of BMI, number of children, number of natural deliveries, tumor size, metastasis, consumption of canned food, tobacco use, and breastfeeding affected patients’ survival based on type I Dagum distribution. Conclusion: The results of the present study demonstrated that the Bayesian nonmixture cure model, with type I Dagum distribution, can be a good model to determine factors affecting the survival of patients when there is the possibility of a fraction of cure. In this study, it was found that adapting a healthy lifestyle (eg, avoiding canned foods and smoking) can improve the survival of breast cancer patients.
- انتشار مقاله: 07-07-1398
- نویسندگان: Shideh Rafati,Mohammad Reza Baneshi,Abbas Bahrampour
- مشاهده
- جایگاه : پژوهشی
- مجله: Addiction and Health
- نوع مقاله: Journal Article
- کلمات کلیدی: Homeless youth,alcohol drinking,Injections,Logistic models
- چکیده:
- چکیده انگلیسی: Background: Alcohol use and drug injection are prevalent among homeless youths. The aim of this study was
to identify the associated factors of alcohol consumption and drug injection among homeless youths aged
18-29 years.
Methods: Data on 202 homeless youths (111 males and 91 females) were collected using a standardized
questionnaire and face-to-face interview. Lasso logistic regression was applied to determine the impact of
associated factors on alcohol consumption and drug injection.
Findings: The mean age of the participants was 26.30 ± 3.19 years. Also, the prevalence of alcohol
consumption and drug injection was 33.0% [95% confidence interval (CI): 30-36] and 4.0% (95% CI: 0-8),
respectively; 6 people (3.0%) consumed alcohol and injected drugs at the same time. Correlates of alcohol
consumption and drug injection were male sex [odds ratio (OR)Alc = 5.7], age (ORAlc = 0.96 and ORDI = 0.98),
bachelor or higher education level (ORAlc = 1.34), non-Iranian nationality (ORAlc = 0.05 and ORDI = 0.18),
food score (ORDI = 0.92), smoking (ORAlc = 2.05), substance use (ORAlc = 1.12), opposite sex relationship
(ORAlc = 1.6), homosexual relationship (ORAlc = 3.56 and ORDI = 2.69), and mental disorder (ORAlc = 0.99).
Conclusion: Based on our findings, it seems that the homeless youth are more desired to use alcohol and drug
injection, whereas the prevalence of alcohol consumption and drug injection in homeless youth was higher
than general youth population in Iran. Therefore, some suitable solutions are needed to prevent the
homelessness. Also, the effective variables that were identified in this study for alcohol use and drug injection
can help design and implement beneficial interventions.
- انتشار مقاله: 17-09-1398
- نویسندگان: Abolfazl Hosseinnataj,Abbas Bahrampour,Mohammad Reza Baneshi,Samira Poormorovat,Glayol Ardalan,Farzaneh Zolala,Naser Nasiri,Jasem Zarei,Ghazal Mousavian,Abedin Iranpour,Hamid Sharifi
- مشاهده