Iranian Journal of

  Background & Objectives : Management of time-dependent variables is the advantages of survival analysis. This study compares time-dependent and -independent variables in survival analysis in culling of dairy cows.

  Methods: In this historical cohort, 7067 dairy cows in the Province of Tehran were recruited. Cows were followed to the next calving or culling. Data on the occurrence of health disorders, calving season, parity, and milk production was obtained. Model 1 treated diseases as time-independent covariates. In models 2, up to 5 diseases were considered time-dependent covariates. For each observation, we split follow-up time in intervals each corresponding to a different lactation month using Lexis expansion of the original dataset. Model 2 assumed that an animal experienced a certain disease from the beginning of the occurrence of that disease by the end of the period. Model 3 assumed that cows were at risk from the begging of the study until the disease occurred (inverse of model 2). In models 4 and 5, an animal was assumed to experience a certain disease for 1 month if the disease occurred during this period. In Model 4 assumed diseases occurred only one time, and in model 5, multiple disease occurrences at different months were considered as different episodes.

  Results : AIC in model 1 and 5 was 10809 and 10366 moreover, BIC was 10926 and 10528. According to this numbers and the shape of the Cox-Snell Residuals, model 5 with Gompertz distribution was the best model.

  Conclusion : Models without time dependency tended to seriously underestimate the risk of a disease on culling.

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.

financial protection against health expenditures is a major goal of health system policymaking. governments have focused on the risk that high health expenditures pose to the financial security of deprived and vulnerable populations. Health systems need to be sure that people receive health services and are protected from the financial burden of health costs. There is no accepted standard for measuring the degree of financial protection. In the literature, there are different approaches to measure the degree of financial protection. Measuring the extent of financial risk is complicated by the fact that the significance of a given risk depends on both the size of the risk and the economic status of the person incurring the risk. Another reason for this complication is that financial risk can also affect the health status. The seriously ill may not receive adequate care if the financial burden on them contributes to a decision not to seek care. Their injury from a lack of risk protection, therefore, may show up as diminished health status and not as a financial loss. The aim of this article is to provide the methodology of the assessment of financial protection against health costs with focus on catastrophic health expenditures. First, we describe and explaine the methodology of measuring the expenditures (based on the WHO approach). Then, we interpret variables used in estimating these costs. Finally, overall discussion and conclusions will be provided in relation to the subject.

The time series is a collection of observation data that are arranged according to time. The main purpose of setting up a time series is to predict future values. The first step in time series data is graphed. Using graphs can provide general information such as uptrend or downtrend, seasonal patterns, periodic presence, and outliers in time series graphs. After graphing the data, if a good forecast is required, stationary data can be used. Differencing or decomposition methods can be used to make the data stationary. Then, a correlogram can be used to identify the order moving average and autoregressive model. The parameters of the model are examined using T-test. If the parameters are significant and the residue is independence, the predicted values can be evaluated using the mean absolute percentage error.

Background and Objectives: Managers need the results of scientific researches for executive planning. Considering some methodological errors in reported studies in Iran and the lack of specific and summarized references, this article aims to provide practical considerations in elderly studies.

Methods: In this narrative review, we conducted a comprehensive search in all accessible electronic data bases using “epidemiology” or “methodology” and “elderly” or their synonyms as keywords. Related papers and books were selected. After review, considerable notes were extracted and presented.

Results: Considering attrition, death, and non-response rates in sample size calculation, proportional sampling from all strata, and considering differences in clinical manifestations and diagnosis are important. Matching for main confounders, considering recall bias, creating a quiet and comfortable environment to conduct the interview, allocating a certain percentage of participants to high risks, registering age and other quantitative variables in detailed and non-categorized formats, home visit for interview after receiving informed consent from the elderly or their guardians, interview at the closest location to the elderly’s residence, avoiding long interviews, considering bold and legible words in designing the questionnaire, data re-checking with proxy and documents, applying age and sex adjustment for rates, evaluating the functional status, appropriate interpretation related to odds ratio and considering the cost of the studies are the most essential considerations in aging studies.

Conclusion: Using epidemiological methods with respect to the characteristics of the elderly enhances the quality of the collected data. Well designed studies provide policy makers with reliable evidence for planning.

Background & Objectives: The number of road traffic accidents (RTAs) and their mortality are increasing in the world. In Iran, RTAs have caused life losses and economical damages. Death is the most important consequence of the accidents in terms of social, economic, and even political expenditures. This paper reports the statistics of the mortality status in the last decade.

Methods: A 10-year study was conducted on national and provincial data of the last decade collected by Legal Medicine Research Center. The population information provided by the National Center of Statistics was used. SPSS 15.5 and Microsoft Office Excel 2007 were used for data analysis.

Results: Between 2001 and 2010, the annual average of 34.6 per hundred thousand people were killed in traffic accidents, more than 80% of the casualties are men. The highest number of deaths and injuries was observed in 2005 and the lowest occurred in 2001. RTAs had a descending trend trough the last decade but the rate of injuries increased. The death rates in Semnan, Qazvin, and Kerman were the highest and in Tehran, Ardabil, and West Azarbaijan were the lowest.

Conclusion: Although mortality rates due to RTAs declined during the last four years of the study period, direct and indirect costs of deaths resulting from RTAs in Iran are a sign of crisis.

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.

Background & Objectives: Home-related traumas are the most common traumas and are ranked the second among different types of traumas. This study aimed to determine the status of home-related traumas in patients referred to medical centers in Kashan in 2010-2012.

Methods: In this cross-sectional study, 1028 patients referred to Kashan emergency medical centers were evaluated. The continuous sampling method was used for patient selection. The data collection tool was a researcher made questionnaire with two sections: demographic information and a checklist to evaluate the domestic trauma. Information was obtained by trained nurses through direct interviews with the patients and hospital records. Data was analyzed using SPSS version 0.16.

Results: Location patterns of incidents showed that the hall (27.7%), kitchen (20.3%) and yard (18.4%) were the most common injury sites. Recklessness (80.8%) was the most common cause of trauma. Most of the accidents were caused by falls (27.90%) and cutting tools (25.08%). Orthopedic injuries (50.2%) and hemorrhagic events (34.70%) were the most common traumas.

Conclusion: The results showed that domestic traumas often occurred following reckless behaviors. As a result, these traumas could be predicted and prevented by concentration and attention during working. To reduce the incidence of domestic traumas, people should receive information and training on health and safety issues in the home setting.

Background & Objectives: In recent years, different decision support systems (DSS) have been used to predict and diagnose diseases. The purpose of this paper was to compare some DSSs and to evaluate their accuracy in predicting diabetes. 

Methods: In this research, determination and optimization of the weights of the neural network were undertaken using genetic algorithm and Levenberg-Marquardt (GALM). Traditional and K-Fold Cross Validation were used to verify the models. Finally, the proposed model (i.e. GALM) was compared using logistic regression and genetic algorithm based on area under curve (AUC), and Confusion Matrix.

Results: After evaluating the results, the model based on the GALM algorithm showed better sensitivity and specificity in comparison with models based on the logistic regression (LR) and genetic algorithm (GA). Furthermore, among other models, the proposed model had a high sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and a small negative likelihood.

Conclusion: The results showed that the GALM model with a sensitivity, specificity, PPV, NPV, and AUC of 98.7, 90.01, 91.8, 98.3 and 0.979 respectively was an appropriate model for predicting diabetes in comparison with models of GA and LR.

Background & Objectives: Urinary calculi are a common problem worldwide. The pattern of fluid consumption in healthy people and patients with renal calculi is not totally clear. The aim of this study was to determine the association between the amount of fluids intake and urinary calculi.

Methods: In this case-control study, cases were the patients with urinary calculi admitted to Emam-Hossein Hospital, Shahroud, Iran. The controls were selected among the patients admitted to other wards of the hospital except for dialysis and ICU wards. The association between independent variables and urinary calculi was investigated using logistic regression analysis.

Results: A total of 127 people (60 cases and 67 controls) participated in this study. The mean age of the participants was 44.6 years (SD = 1.7). The mean intake of tea, natural juice, alcohol free beer, and total fluid intake were higher in cases compare to controls. In participants with a negative history of urinary calculi, the total intake of fluid (P=0.021) and natural juice (P=0.006) was higher in cases. The male gender (OR=3.2), higher BMI (OR=1.2), and a positive family history of urinary calculi (OR=3.5) were associated with renal calculi in a multivariate logistic regression model, while the milk intake (OR=0.995) was a protective factor in this model.

Conclusion: Milk intake is a protective factor and the male gender, higher BMI and a positive family history are the risk factors for urinary calculi.

Background & Objectives: Measuring the impact of various diseases on Life Expectancy( LE) is an important step toward prioritization in health. The present study was conducted to measure the impact of heart diseases, neoplasm, and respiratory diseases on life expectancy (LE) in 2010.

Methods: Data on death and population for all 22 districts of Tehran were obtained from the main cemetery of Tehran and statistical center of Iran, respectively. Age-specific mortality rates and consequently LE were calculated for all 22 districts and both genders. Finally, the death probability assuming complete elimination of the diseases was calculated and the resulting life tables were obtained.

Results: The LE at birth was estimated 74.6 and 78.4 years for total males and females in Tehran, respectively. The maximum and minimum LE at birth was 80 years in females and 72.7 years in males, respectively. Assuming complete elimination of heart diseases, the LE increased to 82.39 and 85.51 years in males and females, respectively while complete elimination of neoplasm resulted in an increase in LE to 76.27 years in men and 80.49 years in women. Finally, elimination of respiratory diseases increased the LE of men to 75.98 years and the LE of women to 79.97 years.

Conclusion: The results indicated the high impact of the diseases on LE, especially the heart diseases. As a main result, LE will upgrade to more focus on this category. 

Background & Objectives: Community assessment is a key tool for improving and promoting the health of the community. The role of community assessment is to identify the most important factors affecting the population health. To get a comprehensive picture of problems, priorities and suggested community health action plans in Iran, this review aims to summarize community assessments in various areas of Iran conducted between 1992 – 2013.

Methods: This study was a retrospective review in which community assessments were compared and the results of several studies conducted in different regions of the country covering both rural and urban health centers were analyzed. Since 1999, department of Epidemiology and Biostatistics has conducted these community assessments in eight phases and follows 2002 North Carolina Community Health Assessment model. Assessment teams typically included MPH students and/ or PhD and masters (epidemiology) students from the School of Public Health. Data was collected through observation, interview, and focus group discussion. Assessment teams in each region prioritized the list of problems using Hanlon method and Nominal Group Technique.  

Results: The results identified substance abuse, economical, and water-related problems as the most important problems in different parts of the country which indicates the need for developing a comprehensive action plan andimplementing measures.

Conclusion: A review of the community assessments performed in this study shows the ability of community assessment to detect community health problems in all aspects. Therefore, this approach is recommended to evaluate and prioritize health problems and to formulate action plans.

Background & Objectives: The aim of the study was to determine age, period, and cohort effects on trend of alcohol and drug use in the students of Tehran University of Medical Sciences from 2006 to 2009.

Methods: Between 2006 and 2009, the students of Tehran University of Medical Sciences were surveyed annually using a structured self-administered and anonymous questionnaire. Intrinsic estimator, which is a new method for resolving linear dependency between age, period, and cohort in linear regression models, was used for data analysis.

Results: In the present study, in the descriptive method, the prevalence of alcohol consumption increased in males and females with an increase in age. The prevalence of illicit drug use was higher in 2007 in comparison with other periods for males and females. In the analytical method (intrinsic estimator), there were no age, period and cohort effects for alcohol and drug use for females. For males, the age effect exhibited an increasing-decreasing-increasing trend and period and cohort effects showed a decreasing trend for alcohol use. As for drug use, the age effect exhibited gradual increases. The period effect displayed an increasing-decreasing trend and the cohort effect exhibited an increasing-decreasing-increasing trend.

Conclusion: The IE method showed no age, period and cohort effects for alcohol and drug use in females. The prevalence of drug and alcohol use increased with an increase in age in males. The high prevalence of drug use could be due to easy accessibility and low price of drugs.

Background & Objectives: This study was conducted to evaluate the completeness and geographical representativeness of the hepatitis B surveillance system between 2007 and 2013 in Hamadan Province.

Methods: In this descriptive study, all reported cases in Hamadan Province were extracted. The analytical literature review method was used to examine completeness. We used studies on the prevalence and incidence of hepatitis in Iran published between 2007 and 2013. Sensitivity analysis of the results was performed by simulation program using the R software. Geographical representativeness was assessed and plotted by the ArcGIS software, as well.

Results: Totally, 1378 cases were reported to the hepatitis B surveillance system in Hamadan Province. Most cases were from urban areas and were men, married, and housewives mostly in the age group 20 to 29 and 30 to 39 years. Completeness of the hepatitis B surveillance system was 77%. The hepatitis B surveillance system was not representative in terms of occupation but was representative in terms of age, sex, marital status, and place of living.

Conclusion: We concluded that the hepatitis B surveillance system had a relatively good performance. Moreover, findings of the analytical literature review method are affected by the included studies and interpretation of the results should be performed with caution.

Background and Objectives: Disorders of height and weight growth are the most important health disorders affecting children younger than two in developing societies. Failure to treat these disorders can lead to the increased mortality and mental, emotional or physical disability. The objective of this study was to investigate the growth trends of children and the factors affecting it.

Methods: This retrospective cohort study was conducted on 2030 children younger than two in Khorramabad, Iran who were selected using stratified and cluster sampling. Based on household records, the weight growth trend was recorded as a four-level variable (decline, stagnation, slowness and desirable) and the the height growth trend was recorded as a three-level variable (stagnation, slowness and desirable); finally, the data were modeled using a longitudinal marginal model and the SAS software version 9.2.

Results: The incidence of at least one decline in the weight growth curve and one stagnation in the height growth curve was 14.2% and 10.4%, respectively. The child’s age and the maternal educational level had a significant effect on the growth trends. However, the sex, parity and the exclusive breastfeeding during the first six months had no significant relationship with the growth trends.

Conclusion: Given the results and the relatively high prevalence of growth disorders among children, it seems that increasing the awareness of low literate women about feeding of the children is the most important approach to manage growth disorders. Additionally, health-care professionals should mostly focus on monitoring the growth of children older than 12 months.

Background and Objectives: In this regard, in addition to reducing exposure, the most effective way to prevent hepatitis B is vaccination. The coverage of hepatitis B vaccination in the Iranian Health Personnel is reportedly different in various studies and there is not an overall estimate of it. Therefore, the present study was conducted to determine the immune response to hepatitis B vaccine among Iranian Health Personnel using the meta-analysis method.

Methods: This study was a systematic review of the Iranian databases, including Magiran, Iran Medex, IRANDOC, SID, MEDLIB and international databases, including Scopus, PubMed, ScienceDirect and the Google Scholar search engine without any time limit to 2015 using standard Persian and English keywords. Searches were conducted by two researchers independently. Meta-analysis was performed using STATA, version 11.1 to combine data through Random Effects Model.

Results: We evaluated 6311 subjects in 21 studies. The history of injection and complete coverage of hepatitis B vaccination in the Health Personnel was 86.9% (CI: 95%, 83-90.7) and 70.3% (CI: 95%, 65.6-75), respectively. The minimum and maximum vaccination coverage were related to the North (52.7%) and West of Iran (87.2%), respectively.

Conclusion: The coverage of hepatitis B vaccination in Iranian Health Personnel is less than European countries, which requires new management strategies and policies to maximize hepatitis B vaccination in high risk professional groups.

Background and Objectives: completeness of registration is used as one of the measures of the quality of a cancer registry, which is the degree to which reportable incident cases of cancer in the population of interest is actually recorded in the registry.

Methods: After removing the duplicates, a total of 471 new cases of esophagus cancer reported by three sources of pathology reports, medical records, and death certificates to Ardabil Province Cancer Registry Center in 2006 and 2008 were enrolled in the study. The incidence rate was estimated based on the capture-recapture method and the use of the log-linear models. BIC, G2 and Akaike statistics were used to select the best-fit model.

Results: In this study, a model with linkage between pathology reports and medical records and a model with death certificates alone, independent of the previous two sources, was the best fitted model. The estimated total completeness of esophagus cancer in 2006 and 2008 was 36% .The source that had the most completeness for esophagus cancers was pathology reports with 21.17%. The estimated incidence rate calculated by the log-linear method for the years 2006 and 2008 was 49.71 and 53.87 per 100,000 population, respectively.

Conclusion: Based on the obtained results, it can be concluded that the low degree of completeness in Ardabil Province requires some changes in data abstracting and case finding such as the use of personal national code and electronic health records to create a more accurate cancer registry.

Background and Objectives: Breast cancer is one of the most common cancers among women and is the second main cause of death after lung cancer. The objective of this study was to use the Bayes model to analyze the prognostic effects on the survival of the women with breast cancer after surgery in the south of Iran.

Methods: The date was collected 1192 women who had breast cancer in Namazi Hospital Research Center between 2001 and 2006. The complete information of only 1148 of them was registered. Parametric Bayes and Bayes Cox methods were used. Considering 0.05 as the level of significance, the data analysis was done using the WinBUGS14 software.

Results: The mean age of the patients (at the time of diagnosis) was 47 years in this study. Cox one-variable analysis showed a significant relationship between survival and smoking (P=0.009), bone metastasis (P=0.01), the number of lymph nodes (P=0.001), the tumoral level of malignancy (P=0.001), the surgical method (P=0.015), financial status (P=0.025), and the tumor size (P=0.001). By fitting Bayes models the variables tumor size, level of malignancy and number of lymph nodes were significant.   

Conclusion: The results showed that clinicopathological features of cancer had a significant role in the survival of the patients.

Background and Objectives: Food insecurity is a major public health problem. The impact of unplanned pregnancy on the physical and mental health of the mother and the fetus is unfavorable. This study was conducted to compare the relationship between food insecurity and some demographic and socioeconomic characteristics, fertility, and pregnancy in women with planned and unplanned pregnancy in Falavarjan in 1393 (2014).

Methods: This case-control study was performed on 200 women with unplanned pregnancy (cases) and 200 women with planned pregnancy (controls) using systematic random selection. Information was collected through researcher-made and Food Security questionnaires (USDA) through interviews with the mothers. Data was analyzed with the SPSS software version 16.0 and chi-square, t-test, Mann-Whitney test, correlation coefficient, and logistic regression.

Results: The prevalence of food insecurity was significantly higher in cases (51%) than in controls (37%). Food insecurity increased the risk of unplanned pregnancy by 1.15 times (CI 95% for OR 1.08-1.22). The risk of unplanned pregnancy, in terms of food insecurity without hunger was 0.324 times more than food security conditions. The odds increased in the state of food insecurity with hunger. In groups, demographic characteristics (except for the age of the household head in the control group), fertility and pregnancy had a significant direct relationship and socioeconomic status had a significant inverse relationship with the household food security.

Conclusion: Food insecurity is associated with demographic and socioeconomic characteristics and the history of fertility and pregnancy. Unplanned pregnancy endangers the outcome of pregnancy and the health of the future generations.

Background and Objectives: Missing data is a big challenge in the research. According to the type of the study and of the variables, different ways have been proposed to work with these data. This study compared five popular imputation approaches in addressing missing data in the questionnaires.

Methods: In this study, 500 questionnaires were used for self-medication in diabetic patients. Missing in the observations was artificially generated by random selection of questions and then deleting them. Five imputation ways included: 1) the mean of the questions, 2) the mean of the person, 3) the mode of the person, 4) linear regression, and 5) EM algorithm. For each method, the mean and standard deviation were compared with imputation. The Spearman correlation coefficient, the percentage of incorrectly classified and kappa statistic were also calculated.

Results: A kappa higher than 0.81 represented almost perfect agreement at 10% missingness. The EM algorithm showed the highest level of agreement with the results of actual data with a Kappa of 0.886. With increasing missingness to 30%, the EM algorithm and the mean of  the person showed a rather similar agreement with a Kappa of 0.697 and 0.687, respectively.

Conclusion: In this study, the EM algorithm was the most accurate method for handling missing data in all models. The mean of the person method is easy for handling missing data, especially for most non statisticians.