Iranian Journal of Epidemiology

Determinants of Social Capital in Tehran Residents Using Path Analysis: Urban HEART Study

M Asadi Lari

Background and Objectives: Social capital consists of individuals' communicational networks, social norms such as mutual trust and cooperation in social networks. The aim of this study was to develop a model to assess the implication of different determinants such as age, gender, occupational status, mental and physical health on social capital components to draw a correlation network for social capital determinants.
Methods: For the purpose of this study, data was used from ‘social capital' section of Urban HEART-1 survey, which included 22,500 households from all 22 districts of Tehran, who were approached in a randomized multistage cluster sampling method. Path analysis is a statistical method to test hypothetical causal models, which requires various causal (path) diagrams. To demonstrate the causal models of social capital, the hypothetical paths of various components were developed and the final model of social capital was drawn using multiple regression analyses.
Results: Path analysis indicated that social capital components are influenced by various variables: A) Individual trust, by occupational status, marital status, and physical component of health-related quality of life B) Cohesion and social support, by education, age, and marital status C) Collective trust and associative relation, by family size, age and physical health. Direct effect of these variables on social capital components was more than their indirect effects (through mental health and physical health).
Conclusion: Social capital components are directly affected by occupational, marital, educational status, family size, physical health and duration of local residency. Planning to improve educational and occupational status, strengthening family bonds and provision of local facilities, may improve social capital.

Evaluation of Prognostic Variables for Classifying the Survival In Colorectal Patients using The Decision Tree

E Hajizadeh

Background & Objectives: Identifying the important influential factors is a great challenge in oncology studies. Decision tree is one of methods that could be used to evaluate the prognostic factors and classifying the patients' homogeneously. This method identifies the main prognostic factors and then determines the subgroups of patients based on those prognostic factors. The aim of this study was to assess the prognostic factors and homogeneous subgroups of colorectal patient through survival tree.
Methods: Data collected from an observational of 739 colorectal patients registered in the cancer registry affiliated to the center of Research Center of Gastroenterology and Liver Disease (RCGLD), Shahid Beheshti Medical University, Tehran, Iran. Death was the interested event and the survival time was calculated from date of diagnosis until occurrence of event (or censoring) in months. Finally we used decision tree based method for classifying and analyzing the data.
Results: Based on our result, decision tree identified four covariates as important prognostic factors in 0.05 significant levels: general stage of cancer, age of diagnosis, histology of tumor and morphology type of tumor. Also patients based on these prognostic factors divided into five homogeneous subgroups. The greater values of measure of separation (SEP) criterion support the appropriateness of this model for such the data.
Conclusion: Decision tree is powerful and intuitive method. It has a key feature that is in addition to evaluate the prognostic factors, provides the homogeneous subgroups for future analysis.

A New Method for Correcting Verification Bias in Diagnostic Accuracy Studies Using A Bayesian Approach

M Shamsipour

Background & Objectives: One of the problems of diagnostic accuracy studies is verification bias. It occurs when standard test performed only for non-representative subsample of study subjects that diagnostic test done for them. In this study we extend a Bayesian method to correct this bias.
Methods: Patients that have had at least twice repeated failures in cycles IVF ICSI were included in this model. Patients were screened by using an ultrasonography and those with polyps recommended for hysteroscopy. A logistic regression with binomial outcome fit to predict the missing values (false and true negative), sensitivity and specificity. Bayesian methods was applied with informative prior on polyp prevalence. False and true negatives were estimated in Bayesian framework.
Results: A total of 238 patients were screened and 47 had polyps. Those with polyps are strongly recommended to undergo hysteroscopy, 47/47 decided to have a hysteroscopy and 37/47 were confirmed to have polyps. None of the 191 patients with no polyps in ultrasonography had hysteroscopy. The false negative was obtained 14 and true negative 177, so sensitivity and specificity was estimated easily after estimating missing data. Sensitivity and specificity were equal to 74% and 94% respectively.
Conclusion: Bayesian analyses with informative prior seem to be powerful tools in simulation experimental

A Comparison Between Weibull, Gama, Log -Normal and Log -Logistic Mixture Cure Models in Survival Analysis of Patients Undergoing (Continuous Ambulatory Peritoneal Dialysis) CAPD

M Hosseini

Background & Objectives: Peritoneal dialysis is one of the most common types of dialysis in patients with renal failure. However multivariate analysis such as log- rank test and Cox have usually used to evaluate association of risk factors in survival of this group of patients, the aim of this study was to perform of Weibull, Gamma, Lognormal and Logistic Mixture cure models in survival analysis of these patients.
Methods: Data of 433 patients undergoing CAPD who registered in two centers in Tehran, Iran between 1997 to 2009 were used in this analysis. We investigated center, gender, age, cholesterol, Low Density Lipoprotein (LDL), High density lipoprotein (HDL), triglyceride, albumin, hemoglobin, creatinine, Fasting Blood Sugar (FBS), calcium and phosphorous as variables effect with Kaplan-Meier and cure model. CUREREGR module was used for survival analysis.
Results: Comparison of AIC (Akaike Information Criterion) of Weibull, Gama, Lognormal and Logistic Mixture cure models showed that Weibull distribution AIC is lower for almost all variables than other distributions. Weibull distribution has better fitness for data than others. In the multivariate Weibull model, age and albumin variables had significant effect on long-term survival of patients (P<0.01). Triglycerides effect on long-term survival had borderline (P = 0.065). Also HDL, FBS and calcium were significant on short term survival (P<0.01) but significance of LDL was borderline (P=0.088).
Conclusion: Cure models have the ability to analyze dialysis patients' survival data and can differentiate long-term survival from short- term survival. The interpretation of survival data with these statistical models could be more accurate and would help to make better prediction for patients by health care professionals.

Predicting Factors of Short-term Survival in Patients with Acute Myocardial Infarction in Isfahan Using a Cox Regression Model

H Baradaran

Background & Objectives: Despite decreasing the trend of coronary artery diseases in developed countries and outstanding improvements in clinical management of these patients, case fatality rate after an acute myocardial infarction (AMI) remains high in both genders. Identifying predicting factors of short-term survival in patients with AMI may play an important role in reducing mortality in these patients.
Methods: In this cohort study, all patients with acute myocardial infarction (AMI) admitted to all hospitals in Isfahan, Iran, during 2000-2008 which registered in Isfahan cardiovascular research Institute were analyzed. We used Cox regression models, uni- and multi-variable analysis.
Results: Within the study period, 8800 AMI patients (73.6% male) were admitted with mean age of 61.85±12.5, and overall 28-day survival of 90.5%. Relative risk (RR) of death for 50-70 years old patients was 2.5 (CI:2-3.1), for over 70 years old RR=5 (CI:4-6.3), for women RR=1.7 (CI:1.5-1.9), for patients who had not received streptokinase RR=0.9 (CI:0.8-1.1), for inferior MI RR=4.2 (CI:2.2-7.8) and for anterior MI, RR was equal to 7.2 (CI:4-13.3).
Conclusion: Recognizing the predicting factors of short-term survival of AMI patients may help health professionals to provide better healthcare services for more at risk patients, i.e. elderly, women and patients with an anterior MI.

Epidemiology of Seizure in Children of Bandar Abbas in 2008 Year

Z Khademi

Background & Objectives: Convulsion is the most common pediatric neurological problem that requires special attention in this group. The purpose of this study was to determine the frequency of seizures and to evaluate its risk factors in children in Bandar Abbas, Iran
Methods: A retrospective study was conducted on 222 children with seizures admitted to children hospital during 2008.
Results: Of total children hospitalized due to seizure, 64.5% were male with age range 1-2 years. Fever was the most cause of seizure. In 58.8% of cases, the child's age at the time of first convulsion was 1-3 years. The seizure attack occurred in wake up in 63.8% of cases, and 65.8% of the samples had normal consciousness at the time of admission. The mean duration of seizure in 64.1% of cases was less than 5 minutes and type of seizure in 80.1% has been reported as generalized tonic colonic. A history of convulsion in other family members was reported in 28.9% and in 19.36%, there was close family relationship between parents. There was no significant relationship between type of delivery, gestational age and birth weight with type and duration of seizure (P>0.05).
Conclusion: Particular attention should be paid to children with seizure during history-taking and be more vigilant to high-risk patients and those who might need prophylactic anticonvulsants.

Epidemiology of Burn in Fars Province in 2009

P Bagheri

Background & Objectives: Burns is one the important injuries which may result vital impairment and disability. Burn injuries are still common particularly in developing countries. Assessment of the epidemiology of burns is very important to make effective preventive methods. This study was conducted in Fars province to assess and describe the epidemiology of burns including its main causes, and its demographic factors.
Methods: All epidemiological data of patients with burn admitted to the hospitals in Fars province during 2010 were analyzed in this descriptive study.
Results: Total of 328 patients with mean age 25.93±17.94 were included. It consisted of 178 male patients (54.3%) and 150 female patients (45.7%), The most common accident age was 26 years, the average percentage of burn was 36.63± 26.63%, average hospital stay in hospital was 13.40±12.72 days, 249 cases had unintentional injury (91/75%) and 79 cased had intentional (24.9%), The main reason for intentional burns was divorce (16.76%), the most common month accident was December, the overall cumulative incidence of burn injuries was 7.28% in 100000 people (person per year) and the burn fatality rate was 29.88%
Conclusion: Epidemiology of burn injuries in Fars province indicates that effective public health programs on this issue would help to reduce the incidence of burn injuries in this region.

Quality of life among Disabled and Non-Disabled Individuals A Comparative Study

M Karimlou

Background & Objectives: The aim of this study was to identify the quality of life (QOL) measures commonly used to assess disabled people compared to healthy individuals.
Methods: A cross-sectional study was conducted in 1000 disabled and healthy individuals aged between 15 to 75 years old during 2009 year. These groups were selected by random sampling method multistage cluster sampling from Crescent Comprehensive Rehabilitation Center located in Tehran. WHO's Quality of Life (WHOQOL-100) questionnaire was used to measure quality of life.
Results: The Mean age were 35.9±12.9 and 35.1±12.7 years amongst disabled and non disabled groups, respectively. There was a significant difference between two groups in terms of somatic health and independence of quality of life (P<0.001), in which the mean score in both domains were high in healthy individuals. No significant difference was observed between two groups in other scopes.
Conclusion: Findings of this study highlighted the lower quality of life in disabled people in Tehran, Therefore this group should be targeted for any relevant intervention in order to improve their care.

Sleep Quality of Students living in Dormitories in Tehran University of Medical Sciences (TUMS) in 2011

Z Tavakkol

Background & Objectives: Sleep quality is an important factor in student life and affects in their learning process. Sleep problems are related to increased health concerns, irritability, depression, fatigue, attention and concentration difficulties, along with poor academic performance. The aim of this paper is to conduct a survey based on a questionnaire that would characterize the quality of sleep in students living in dormitories of Tehran University of Medical Sciences (TUMS).
Methods: We conducted a cross-sectional study using the stratified random sampling approach on 277 students residing in dormitories in Tehran. A demographic questionnaire and Pittsburgh Sleep Quality Index (PSQI) were used for data collection.
Results: Mean (CI) of PSQI in students was 8.57 (8.10- 9.04). Using the cut-off score of 6 for the PSQI global score, 73.3% (68.1%-78.5%) of students were described as poor sleeper. Female students had a worse quality of sleep compared to male. The mean duration of sleep in students was 5:15´± 105´ (hours). This was significantly higher in male students than female students. There were no significant relationships between demographic variables such as age, academic level, marital status and family income with and quality of sleep.
Conclusion: This study showed that poor sleep quality is prevalent among students living in dormitories of TUMS. Therefore it is necessary to provide effective educational interventions for this group in order to improve the quality of sleep.

Evaluation of Misconception about Probability among Arak Medical University Students

M Rafiei

Background & Objectives: Misconceptions of mental models are phenomena that very with accepted scientific models. The assessment of misconception in statistics could (would) be very helpful in learning statistics. The probability is one of the important concept in statistics. The purpose of this study was to assess the misconception about probability in students of Arak University of Medical Sciences in 2011.
Methods: This descriptive-analytical study was carried out on 267 medical sciences students enrolled in Arak University of Medical Sciences students during 2011 year. We used a stratified random method in order to collect data and also a standard questionnaire was employed in this study. The data were analyzed by SPSS software with using ANOVA, Chi-Square test, logistic regression, Kruskal-Wallis Test and on proportion test.
Results: The mean score of perception of probability in students was 10.47 with standard deviation 3.47 respectively. The prevalence of probability misconception was 26.2%. There was statistically significance relationship between the prevalence probability misconception and the field of students.
Conclusion: Misconception of (in) probability in teaching biostatistics should be paid more attention in future curriculum development in medical universities.