Showing 12 results for Khalili
R Chaman, A Shamshiri, K Kamali, Ghr Khalili, K Holakouie Naieni,
Volume 2, Issue 1 (23 2006)
Abstract
Background & Objectives: This investigation was prompted by the growing importance of nested case-control studies and the increasing frequency with which they are done in epidemiologic research. After a brief explanation of nested case-control studies, we evaluate the trends in research methodology over the last decade, especially with regard to cohort, case-control, and nested case-control designs.
Methods: Data for this study were extracted from the PubMed database, using these keywords: Nested Case-Control, Risk-Set Sampling and Density Sampling. The search was confined to the 10-year period from 1996 to the end of 2005. As for other methodologies, we used keywords Cohort and Case-Control for a search over the same time period. The search itself was performed on April 25, 2006.
Results: We found 2011 articles reporting nested case-control studies. There were 95 such articles in 1996 the number had increased to 289 in 2005. Case-control and cohort designs accounted for 68456 and 60479 articles, respectively.
The number of case-control articles rose from 4378 in 1996 to 10270 in 2005, while that of cohort articles increased from 2981 to 9771 over the same period.
Conclusions: The number of cohort and nested case-control articles followed similar upward trends over the last decade and their rate of increase was greater than that of simple case-control articles.
D Khalili, F Hadaegh, M Tohidi, A Ghasemi, F Sheikholeslami, F Azizi,
Volume 4, Issue 3 (20 2009)
Abstract
Background & Objectives: Triglyceride/HDL-cholesterol ratio (TG/HDL-C) has been shown as an indicator for metabolic syndrome (MetS). This study aimed to detect the role of this ratio to predict coronary heart disease (CHD) outcome in an Iranian men population with high prevalence of MetS.
Methods: 1824 men ≥ 40 years old, free of clinical cardiovascular disease at baseline, were included in the study from February 1999 to August 2001. Serum level of total cholesterol (TC), HDL-C, TG, and risk factors of CHD including age, systolic blood pressure, diastolic blood pressure, body mass index, diabetes, smoking and family history of cardiovascular diseases were measured at initial phase of study.
Results: During a median follow up of 6.5 years until March 2007, a total of 163 new CHD events occurred. According to a Cox proportional hazard modeling, after adjustment for TC and other risk factors, men in the top quartile of TG/HDL-C relative to first quartile had a significant hazard ratio (HR) of 1.85 (95% CI, 1.07-3.17). Combined HR for TC and TG/HDL-C (men in the top quartiles of both TC and TG/HDL-C relative to first quartiles) after adjustment for other risk factors was 6.13 (95% CI, 2.37-15.86).
Conclusions: The evaluation of both TG/HDL-C ratio and TC should be considered for CHD risk prediction in Iranian male population.
Ss Azimi, D Khalili, F Hadaegh, Y Mehrabi, P Yavari, F Azizi,
Volume 7, Issue 4 (16 2012)
Abstract
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Background
& Objectives: Cardiovascular
disease is the first cause of death and third place in disease burden in Iran.
This study estimates population attributable fraction (PAF) of cardiovascular
risk factors in Tehran population. PAF is one of the important parameters of
measuring population affect of risk factors and evaluating potential impact of
preventive strategies in community level.
Methods: In this study 5868 participants above
30 years old of Tehran lipid and glucose study (TLGS) were employed and 501 CVD
events detected during 10 years follow-up. Direct estimate of adjusted PAFs
using logistic regression which is one of less biased exist methods of PAF
calculation were applied.
Results: Highest modifiable cardiovascular
risk factor PAFs, in sequence, was smoking (14.16%), hypertension (11.73%),
diabetes (7.32%), hypercholesterolemia (6.85%) and central obesity (5.91%) for
men, and hypertension (19.25%), diabetes (18.82%), central obesity(9.88%) and
hypercholesterolemia (7.95%), for women. Also PAF of hazardous age and
premature family history of CVD, as most important nonmodifiable CVD risk
factors, were 36.09%, 16.61% and 3.95%, 7.56% for men and women respectively.
Conclusion:
According to the difference of risk factors PAFs ranking in men and women, it
is suitable that CVD preventive interventions to be prioritized by sex
separately. In this regard, besides special attention to control tobacco use in
men, hypertension and diabetes in both sexes and high cholesterol in men and
central obesity in women respectively, should be given in priority of preventive
strategies.
Z Nourafkan, P Yavari, Gh Roshandel, D Khalili, N Behnam Pour , F Zayeri,
Volume 9, Issue 1 (5-2013)
Abstract
Background & Objectives: Golestan province in Iran has been known as a high risk area for esophageal cancer (EC). This study was conducted to assess the population-based survival rate in EC patients in Golestan province of Iran.
Methods: In a longitudinal study, 223 EC patients registered in Golestan population-based cancer registry in 2007 and 2008 were recruited. Kaplan-Meier method was performed to calculate median survival and log rank test was also used to compare survival rates between subgroups of variables. Multivariate Cox regression model was employed to determine adjusted hazard ratios (AHR) for different variables.
Results: From 223 patient, 129 (57/8%) were male. The mean age of participants was 64/3 years. The median survival in our study was 11/08 months. Survival rates for 6, 12 and 36 months were 69%, 47% and 14%, respectively. The results of Cox regression analysis showed that the AHR for patients with metastasis stage (compared to those with localized stage) was 13.89 (95% CI: 7/93-24/32) and the AHR for workers (compared to clerks) was 2.4 (95% CI: 3/8-1/47).
Conclusion: Our results showed that survival rate of EC patients were higher than the rate reported in a previous study from this region. However the survival rate from this region seems still lower than those reported from developed countries. Implementation of appropriate screening programs in this region will result in early diagnosis of EC and consequently will increase survival rate in EC patients.
Mh Panahi , P Yavari, D Khalili, Y Mehrabi, F Hadaegh, F Azizi,
Volume 9, Issue 4 (3-2014)
Abstract
Background & Objectives: We studied the risk of Chronic Kidney Disease (CKD), Metabolic Syndrome (MetS), and their interaction on the incidence of Coronary Heart Disease (CHD).
Methods: A population of 6568 participants (43.4% male) with a mean age of 48.4 years for males and 46.7 years for females and a median follow-up of 10.1 years was investigated. They were divided into 4 groups at baseline: CKD-/MetS-, CKD+/MetS-, CKD-/MetS+, CKD+/MetS+. Hazard Ratios (HRs) were calculated for each group and were compared to the first group using multivariate Cox regression analysis adjusted for age, education, smoking, total cholesterol, and the family history of cardiovascular diseases.
Results: Men with CKD (without MetS) showed an HR of 1.74 (CI 95%: 1.16-2.60) for CHD events. The measured value was 2.34 (1.77-3.08) for men with MetS (without CKD). The respective results were in women 1.18
(0.64-2.19) and 2.59 (1.73-3.88). CKD and MetS had a significant negative interaction with CHD events (HR=0.40, 0.24-0.66). The interaction was not significant in women (P value=0.48).
Conclusion: The results of this study indicated that CKD without MetS was a risk factor for coronary heart disease in men but not in women.
M Nazarzadeh, D Khalili, B Eshrati, F Hadaegh, F Azizi,
Volume 9, Issue 4 (3-2014)
Abstract
Background & Objectives: The case-cohort study is one of the youngest designs in epidemiology and some methodological aspects of it are still in debate. This study aimed at comparing the estimated hazard ratio, standard error, and interaction hazard ratio between the case-cohort and cohort studies for assessing the relationship between diabetes and cardiovascular diseases.
Methods: A total of 1701 men and 2253 women aged between 40 and 75 years were considered as the main cohort. Subcohort sampling was performed using simple random sampling with a sampling fraction of 0.3%. The hazard ratio of the cohort study was calculated using Cox regression model and the 3 methods of Prentice, Self-Prentice, and Barlow were used for calculating the hazard ratio of the case-cohort study. The mentioned regression models were used to assess the interactions.
Results: The results of the two studies were similar in populations with higher incidence (cohort of men) and lower incidence (the cohort of women) when frequency percent of exposure variable was greater than 10%. When the sample size of the initial cohort was less than 1250 subjects, discrepancies were observed between the results of the two studies. In addition, the standard error of the case-cohort study was higher than the cohort study. The results of both studies were similar in assessing the considered interactions.
Conclusion: The results are similar when the initial cohort sample sizes are sufficient. Meanwhile, unlike the percentage of exposure frequency, the outcome incidence has a negligible impact on the discrepancy between the results while the effect of the relative frequency of the exposure levels on the results discrepancy is noticeable.
K Yazdani, S Nejat, A Rahimi-Movaghar , L Ghalichee, M Khalili,
Volume 10, Issue 4 (Vol 10, No 4 2015)
Abstract
Background and Objectives : In the current age, due to the increasing growth of knowledge and competition therein, evaluation of scientific products by means of scientometric methods has become a very important and necessary subject. Scientometrics, in simple words, is the science of measuring the knowledge. Scientometric indices are divided into three categories: productivity metrics that measure the productivity of the researchers or research groups, impact metrics that assess the quality (or performance) of journals, researchers, or research groups, and hybrid metrics that are used to summarize both productivity and effect metrics in one index. Scientometric studies help policy makers and managers of universities and heads of research centers in allocating budget, creating a balance between the budget and costs, making appointments, and promoting the researchers and institutes, and results in better recognition of weaknesses and strengths of their affiliated groups by evaluation of priorities, perspectives, and capacities. Meanwhile, this new knowledge can help with systematic evaluation and ranking of universities and research centers. This paper provides a review on scientometric concepts and its applications and discussed scientometric indices.
Mh Panahi, P Yavari, D Khalili, Y Mehrabi, F Hadaegh, F Azizi,
Volume 11, Issue 1 (Vol 11, No 1 2015)
Abstract
Background & Objectives: Some studies on chronic diseases have indicated that obesity may result in a paradoxically longer survival. The present study was aimed to investigate the effect of Chronic Kidney Diseases (CKD) and Metabolic Syndrome (MetS) on the incidence of Coronary Heart Disease (CHD).
Methods: In order to record time to CHD events, a sample of 6,507 individuals (mean age 47.4 years, 43.4% males) was followed for nearly 10 years. Participants were also categorized into four groups according to presence/absence of CKD and MetS. Then, using a Multivariate Cox Regression, the Hazard Ratio (HR) of each group was estimated relative to individuals free of both CKD and MetS separately for obese (BMI&ge27.1 Kg/m2) and non-obese persons (BMI<27.1 Kg/m2).
Results: HR for non-obese patients with CKD but not MetS was obtained 2.06 (95%CI: 1.28-3.31) in men and 2.56 (1.04-6.31) in women. However, these associations were not significant for obese patients. Furthermore, among non-obese men and women with MetS alone, HR was estimated 2.52 (1.71-3.73) and 4.68 (2.20-9.95), respectively. For obese patients, these values were 1.70 (1.05-2.78) and 1.90 (1.16-3.13), respectively.
Conclusion: The results reflect that among those who had MetS alone, the risk of CHD incidence was twice higher in non-obese individuals compared to obese patients.
S Akbarpour, Y Jahangiri-Noudeh, M Lotfaliany , N Zafari, D Khalili, M Tohidi, Ma Mansournia, F Azizi, F Hadaegh,
Volume 11, Issue 2 (Vol 11, No 2 2015)
Abstract
Background & Objectives: Considering the importance of CVD risk factors in diabetic and non-diabetic populations and the high prevalence of diabetes and cardiovascular risk factors, we studied the trend of anthropometric indexes, blood pressure, smoking and lipids in diabetic and non-diabetic populations.
Methods: The data of Tehran Lipid and Glucose Study was used in this investigation. The study population comprised 1045 diabetic and 5136 non-diabetic subjects. To investigate the secular longitudinal trends, the Generalized Estimation Equation method was employed. All statistical models were adjusted for age to eliminate the potential confounding effect of age. The interaction between the diabetes status and each phase of the study was checked in a separate model in GEE.
Results: Over a decade, the serum levels of TC, TGs, LDL-C and non HDL-C decreased although about 60% of the diabetic population did not reach the therapeutic goals of non-HDL-C and LDL-C levels until 2011. Control of hypertension was more successful in females, but about 60% of both males and females with diabetes were still hypertensive at the end of follow-up period. Smoking increased during the follow-up.
Conclusion: This study showed that among CVD risk factors, healthcare professionals paid more attention to hypercholesterolemia neglecting other risk factors including hypertension and central obesity.
A Nikfarjam, Ar Shamshiri, Z Hasanpour, M Khalili,
Volume 11, Issue 4 (Vol 11, No.4, Winter 2016 2016)
Abstract
Background and Objectives: Children immunization program is one of the most successful and most cost-effective public health interventions and medical programs. The study was designed and conducted in order to assess the vaccination coverage in areas covered by Tehran University of Medical Sciences (TUMS).
Methods: This study was a cross-sectional study of children aged 24 months to 6 years living in urban areas and high-risk and marginal areas covered by TUMS. Six hundred and thirty children were sampled in 90 clusters in urban areas and cluster sampling as probability proportional to size sampling was performed in high risk areas and a sample size of 768 children was determined. The questionnaires were completed by interview.
Results: In high risk 750 children (97.7%, 95% CI: 96.32-98.60%) and 616 children (97.8%, 95% CI: 96.3-98.78%) in urban areas had complete immunization histories. Furthermore, 98.4% of the Iranian children and 95.0% of foreign children (P=0.019) in marginal areas and 98.1% of the Iranian children and 92.1% of the foreign children (P=0.046) in urban areas had complete immunization histories.Ignorance of immunization program (%50) was addressed as the main reason for incomplete immunization.
Conclusion: Universal mass vaccination coverage of the children and equal coverage in marginal and urban areas indicated the success of the authorities in the implementation of this program. Organizing training courses for mothers on the immunization program, providing the required facilities and services, monitoring and supervision of vaccination and also considering the immunization status of foreign children seem to be essential in maintaining and improving the existing status.
Mr Aflatoonian, M Khalili, M Rahanjam, B Aflatoonian,
Volume 11, Issue 4 (Vol 11, No.4, Winter 2016 2016)
Abstract
Background and Objectives: Q fever is a zoonosis with a worldwide distribution; this disease is a public health concern in many countries. The aim of this study was to determine the association between risk factors with Q fever seropositivity among veterinarians and vet staff in Southern Khorasan.
Methods: Questionnaires were prepared and 92 blood samples were obtained from all veterinary staff in the South Khorasan (East of Iran). The serum samples were tested with an indirect ELISA kit (anti body phase II); then, SPSS version 19.0 was employed to analyze the data using descriptive statistics and a confidence interval of 95%, chi-square test, and logistic regression.
Results: The results showed that 50 serum samples (54.35%) were positive and the results of data analysis with logistic regression indicated an association between seropositivity and contact with animal secretions and abortive materials. There was no correlation between seroprevalence and age, gender, work experience, education, use of unpasteurized dairy products, knowledge of disease, and clinical findings.
Conclusion: In conclusion, the present study showed a high seropositivity rate among vet staff which indicates that further attention should be paid to this disease in these groups.
S Masudi, Y Mehrabi, D Khalili, P Yavari,
Volume 11, Issue 4 (Vol 11, No.4, Winter 2016 2016)
Abstract
In epidemiologic studies, the measurement of characteristics of interest is almost always subject to random measurement error. This error and its effects are usually overlooked by researchers. One of its effects is a widespread statistical phenomenon that is well known as regression to the mean. This phenomenon occurs whenever an extreme group of people is selected from a population based on their measurements of a variable. If a second measurement is taken in this group, the mean of the second measurement will be closer to the mean of the population. In interventional studies, this increase (decrease) might be regarded as the effect of intervention, when in fact it has had no effect. Ignoring regression to the mean will lead to the erroneous conclusions and interpretation of the results of epidemiologic studies and affects the decisions in evidence-based medicine and planning for preventive and public health measures. This paper highlights the importance of this problem and its effects in epidemiologic studies and the ways to avoid it.
