Journal of School of Public Health and

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The purpose of this study was to determine toxoplasmosis seropositivity rates and to record ascending serologic titers in high-school girls. We also searched for possible risk factors. This descriptive-analytic study used 414 serum specimens collected from high school girls in six different regions of Esfahan city through cluster random sampling. The sera were taken from the tip of the finger by hematocrite microtubes. Samples were studied by the Indirect Immunofluorescent Assay Test(IFAT) for estimation of serum titers. Data were analyzed using chi-square (X²) and t tests. The overall seropositivity rate was 18.4% in 14-19 year-old girls and this rate increased with age. IFAT titers in 98% of the positive samples were at 1:100 the remaining 2% showed values above this threshold. For the latter group, we performed another titration test to determine exact titers .The supposed risk factors were age, place of residence, education level (parents and student), consumption of undercooked meat and raw liver, occupation and parent income, and exposure to contaminated material from cats and fowls. The highest positivity rates (27.5%) were recorded in District 1, while the lowest rates (14.5%) were seen in District 5. Significant relationships were found between seropositivity and exposure to cats and fowls.(P>0/05). No significant relationship was observed with the other factors. There was a low level of knowledge about toxoplasmosis and the relevant risk factors: only 2.4% of the subjects were relatively well-informed on this subject. There were not any acute cases. Toxoplasma infection is very important because of its socioeconomic implications, so control measures seem crucial. All seronegative women should be know about this infection and its transmission routes. Education is the most important element in prevention and must be promoted via the mass media, other education systems and the health managers. The studied group in this survey were girls at the usual age of marriage or younger, and it is recommended that health system managers continue to offer education on practices that help prevent infectious diseases in general and toxoplasmosis in particular.

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Evaluation assures the success of each project, program or activity. It is one of the most important components of any management process. Because of its high importance, loss of an effective evaluation mechanism in a hospital not only increases costs, but also endangers community health. The current study tries to assess the perceptions and expectations of hospital managers and decision-making boards in Hamedan regarding the evaluation system and to determine gap between them. This is a cross-sectional study. Its target group in each hospital includes: head, manager, matron, emergency administrator, managers of medical records, laboratory, radiology, pharmacy sections plus the afternoon and night shift supervisors. The study took the form of a census, involving a total of about 400 subjects.The data were collected through a questionnaire and analyzed using the SPSS program . Findings: 1. The highest levels of target group expectation regarding evaluation indices were related to the “patient safisfaction” index. 2. The highest levels of target group perception of the evaluation indices were related to the “ values and norms” index. 3. All the gaps detected between target group’s perception and expectation from evaluation indices were significant. 4.The highest percentage of difference between target group’s perception and expectation was related to the “staff satisfaction” index and the lowest one was related to the “values and norms” Index.

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Human Enteroviruses replicate in gastrointestinal tract and are excreted to the sewage system through feces, so isolation of Enteroviruses from sewage can be considered as a sensitive indicator for virus cirulation in society. They are originally given the name of Enteroviruses, but the inadequacy of this term became apparent when some Coxackie and Echoviruses were also found in acute respiratory infections. Therefore, these viruses can produce acute or paraclinical infecions, the shedding of virus is more than 1010 virus per each gram of feaces. In this study, 63 sewage samples were obtained from the 6 main sewage disposal systems in Tehran by grab sampling: Direct, Pellet, Two–phase methods in 2 sensitive cell lines (Hep2 & RD) and neutralization test were used to determine Enterovirus circulation in one year. None-Typable Enteroviruses, E11 and E25 were isolated more frequently than other Entroviruses. Out of 63 sewege specimens, we isolated 13 (20.63%), 25 (39.68%) & 27 (42.83%) Enteroviruses by Direct, Pellet and Two-phase methods respectively.

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Background and Aim: The aim of this study is to evaluate the familial aggregation of esophageal cancer in a defined population under coverage of Babol Research Station, Institute of Public Health Research, Tehran University of Medical Sciences, in one of the high incidence areas in north of Iran and to assess the risk of disease associated with first degree familial relationship.
Material and Methods: In this study, the data of family members of three to four successive generations and family history of esophageal and other cancers were collected from esophageal cancer cases which occurred between 2001-2003 in Babol district. The pairwise odds ratio of logistic regression method with GEE2 approach used for familial aggregation of esophageal cancer within first degree family. The results have been adjusted on covariates of age and sex of each family member and age and sex of the proband .
Results: The proportion of having a positive family history of esophageal cancer in first relatives is 3.09% (3.8 % in men and 2.3 % in female relatives). The pairwise odds ratio was 1.79 (95% CI :1.1 , 2/93) in first degree family and odds ratio between parent – offspring was 2.21 (95%CI :1.1 , 4/44)and relation between sibling was 1.92(95%CI: 0.87, 4.24) . It was not possible to look for any parent – parent pattern.
Conclustin: We found a familial aggregation between first degree relatives in this area.The association between parent–offspring suggests the presence of a genetic component in this disease.

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Background and Aim: At the outset of the third millennium, vitamin D deficiency is still a common and serious health problem among women of reproductive age and their infants in developing countries. Precise information on the vitamin D status of urban lactating women in Islamabad -Gharb is not available. But it seems that, like in other areas of Iran, vitamin D deficiency may be common in this region. The aim of this study was to determine the vitamin D status in urban lactating women and its association with the following variables: number of pregnancies, total duration of lactation, length of exposure to sunlight, and literacy.
Materials and Methods: Using a simple random sampling technique, a total of 155 lactating women with children under the age of 1 year were selected from 8 urban health clinics. In the interview, the subjects answered questions on the above-mentioned independent variables and fasting blood samples were taken for analysis. The concentration of 25-hydroxyvitamin D in serum was measured by a chemiluminescence method. Normal status was defined as concentration of 25-Hydroxyvitamin D serum ≥ 10 ng/ml, moderate deficiency as concentration ≥ 6ng/ml and <10 ng/ml, and severe vitamin D deficiency as concentration of 25-Hydroxyvitamin D < 6 ng/ml.
Results: The results indicate that only 8.4% of women were normal, 18.7% had moderate deficiency, and 72.9% had severe vitamin D deficiency. The vitamin D status had a statistically significantly negative association with the number of pregnancies and the total duration of lactation.
Conclusion: The vitamin D status of urban lactating women is very poor and needs immediate attention.

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Background and Aim: Breastfeeding is one of the most important health determinants in infancy and childhood: physical growth and mother-child bonding in this period are two factors that program cognitive ability in later life. The main aim of this study was to examine the long-term effects of breastfeeding on subsequent cognitive performance. 

Material and Methods: A cohort of 5362 births registered over a period of one week in March, 1946 was selected by stratified sampling, based on the subjects' social class. We collected data for ages 2, 8, 11, 15, 26, and 46 years, and these data were analyzed in 2004-2005 at the school of public health, Tehran. Linear structural equation models were fitted to the data by LISREL 8.12 software in order to find path models.

Results: Descriptive findings showed that children weighing ≥3500 grams at birth acquired the ability to walk, talk, stand, and sit earlier than others. Also, subgroups within the cohort showed different patterns of change in their cognitive scores. Analysis of variance revealed that after adjustment for sex, social class, age of talking, and age of walking breastfed children still had higher means of verbal and nonverbal scores at ages 8 and 15 compared to never-breastfed children. Path analysis indicated that breastfeeding and birth weight could program later-life cognitive performance directly or indirectly through the ages of 2, 8, 11, 15, 26, and 43 years. For instance, path coefficients from breastfeeding to ages of talking and walking, to 8-15 verbal scores, to 26-year cognitive scores, and then to memory and visual scores at age 43 were estimated -for females and males, respectively- and form left o the right as follows: -0.12 (se=0.02), -0.05 (se=0.02), 0.71 (se=.05), 0.10 (se=0.04) for women    -0.01 (se=0.02), -0.07 (se=0.01), 0.75 (se=0.06), 0.13 (se=0.06) for men.

Conclusion: There are significant relationships between some early life determinants and later cognitive performance we conclude that in longitudinal studies of later life abilities, early-life nutrition and birth weight should be incorporated in the path analysis of aging.

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Background and Aim: Undercounting is a common problem in surveillance systems and registries. One of the procedures has been used for assessing sensitivity of a surveillance system or completeness of a registry is capture-recapture method.The objective of the present study was to estimate the number of deaths due to road traffic injuries applying capture-recapture method and using three data sources: police, legal medicine organization and hospital.

Material and Methods: All of the deaths due to traffic injuries occurred within Kerman district in the year 2000 were derived from police, Shahid Bahonar hospital and Kerman legal medicine data sources. Matching cases between the lists was based on three characteristics: first name, family name and date of accident. Loglinear model was used for statistical analysis.

Results: The total number of identified cases was 471 the best fitted loglinear model estimated the actual  number of deaths as 596 (CI 95%: 543-686). Based on Iranian Statistical Center estimates, the population of Kerman district in the year 2000 has been 644673 so the cause-specific mortality rate of traffic injuries is estimated as 92 (CI 95%: 84-107) per 100,000 population. Therefore the proportion of deaths registered in police, legal medicine and Shahid Bahonar hospital are 16%, 58% and 48% respectively. The coverage of total deaths (471) is about 79%.

Conclusion: The findings showed that none of the data sources had enough coverage of all deaths due to traffic injuries. Capture-recapture estimates can help for obtaining better estimates.

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Background and Aim: Iran managed to eradicate the wild poliovirus in 2000. However, a large number of AFP cases are still detected each year because of close surveillance: there were 450 reported AFP cases in 1382. The expected number of cases for the year 1382 in the province of West Azarbayjan (with an under-15 population of 1100000) was 11, while the observed number was more than 6 times greater (70 cases). In this study we investigated the non-polio enteroviral agent which could cause the AFP cases especially in Azarbayjan Province. Hence, the main purpose of the study was to identify circulating non-polio enteroviruses, using cell lines RD, Hep2, L20 and RT-PCR.

Material and Methods: All stool specimens of AFP cases were treated with chloroform and then injected into the above-mentioned cell lines. The isolated viruses were identified by the NT method. In cases where polioviruses were isolated, intratypic differentiation (wild vs. vaccine strains) using hybridization and ELISA tests. Finally, we performed RT-PCR with pan-EV primers on all samples.

Results: Using cell cultures, we were able to isolate 10 viruses, 9 of which were isolated by the RD cell line and this is regarded as the most sensitive cell line. The RT-PCR also identified 16 different viruses, 7 of which were not isolated on the RD line. Thus, RT-PCR could increase viral detection by 10%, indicating a high degree of high sensitivity.

Conclusion: Although the combination of cell culture and RT-PCR for detection and identification of non-polio enteroviruses causing AFP is invaluable, more than 75% of AFP patients were enterovirus negative. Therefore, they must be checked for other agents such as flavivirus (viral) and Campylobacter jejuni (bacterial).

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Background and Aim: Patients with hemophilia and thalassemia are at high risk for hepatitis C virus (HCV) infections. Unscreened blood and blood products are thought to be the most important risk factors in these two groups.

Materials and Methods: Blood samples were collected from 98 thalassemia patients and 74 hemophiliacs in Markazi province. The presence of anti-HCV antibody was tested by a third generation enzyme immunoassay. All ELISA-reactive samples were tested with the confirmatory third-generation recombinant immunoblot assay RIBA. We used a specially designed questionnaire to obtain data from patients and the software package SPSS 11.5 for statistical analysis.

Results: HCV antibody was detected in 5 thalassemia patients (5.1%) and 31 hemophiliacs (41.9%). Anti-HCV positivity in patients with thalassemia was associated with the total volume of the transfusions, splenectomy, and the duration of treatment. In hemophiliacs, seropositivity was significantly associated with the duration of transfusion treatment (P=0.01) and disease severity (P=0.00). The prevalence of HCV antibody in thalassemia subjects dropped from 8.1% to 0% after the implementation of anti-HCV screening in1996.

Conclusion: In Markazi province, the current policy of screening donors for anti-HCV and the strict safety controls on factor concentrates can effectively protect thalassemia and hemophilia patients from HCV infection.

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Background and Aim: Domestic violence against women is a major health problem, as well as a violation of human rights. It adversely affects the physical, mental, and social well being of women, families and communities. This phenomenon exists in all countries around the world. Although its prevalence, strength, types, effects, and risk factors are different, it is not limited to any geographical zone or distinct social class. This article presents the views of Tehrani couples and experts on underlying factors causing domestic violence against women in Iran and action to be taken for prevention.
Materials and Methods: This qualitative study was carried out through eight FGD meetings, in 2 days, with the participation of 50 couples. The couples were divided into 8 groups based on sex, education, and history of violence. Results of the FDGs were categorized and analyzed. Data were discussed in group meetings of 50 experts in different fields, such as health, medicine, law, education, and Islamic studies, from academic, policy making, governmental executive, and women's affairs organizations, divided into three groups of community general education and information dissemination, health system, and judiciary system. Results were discussed and finalized in a general meeting.
Results: The couples and experts identified underlying factors in 4 categories socio-cultural, economic, legal, and medical. Actions to be taken for prevention and control were believed to be educational, legal, and supporting services.
Conclusion: On the basis of the findings of this study, it was suggested that strategies/actions/services to solve the problem and reduce harm should include providing appropriate information and education for couples and the community emphasizing the health system responsibility empowering physicians and other health personnel to help women who are victims or susceptible to domestic violence legal transparency and reforms meeting legal needs law reinforcement and implementation providing safe shelters for victims and establishment of a national center for research and planning on violence.

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Background and Aim: Environmental health impact assessment of industrial estates will help greatly in better planning for sustainable development and reducing disease risk in a community. The objective of this study was to assess the positive and negative effects of establishing an industrial estate in Jovein, Sabzevar, Iran in 2006-7 and suggest managerial strategies to reduce undesirable environmental health impacts.

Methods and Materials: A modified Leopold Matrix and Scaling checklist method was used. The existing environmental situation was investigated and then environmental impact assessment alternatives were determined, bearing in mind the amounts and kinds of predicted pollutants in the construction and operational phases . The assessment was made considering the immediate, direct, and indirect impacts in the short and long terms. It was attempted to use a wide range of values of different factors (-5, +5) in order to estimate the impact of all activities on the environmental status.

Results: The results of the study are presented with two alternatives, i.e., "No" (conducting the project with no concern for environmental issues), and "Yes" (performance of the project with application of methods to reduce the environmental harmful impacts), when establishing the industrial estate, in the construction and operation phases. The impact assessment with the "No" alternative scored -791, meaning that execution of the project had to be rejected. However, after reducing the harmful impacts the score rose to +252, indicating that the project would be accepted.

Conclusion: The method of reducing harmful environmental impacts along with environmental management programs introduced are accepted in this study. It is recommended that the Ministry of Health and Medical Education and The Iranian Environmental Protection Agency collaborate closely in the area of environmental health impact assessment of industries and industrial estates.

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Background and Aim: The role of fresh water snails as the intermediary host in transmitting parasitic infestations in man and animals is well known. In Iran, urinary schistosomisasis is known to be endemic in the Khuzestan Province, south-west of the country. Considering the Egyptian experience concerning the negative effects of Aswan Dam construction on expanding the prevalence of human bilharziasis, the possible role of huge agro-industrial sugar-cane projects on eliminating schistosomiasis in the only known endemic province of Khuzestan in Iran came to our attention. The main objective of this study was to identify the species of fresh water snails in a vast area under cultivation of sugar cane in Khuzestan province, S.W. Iran.

Methods and Materials: Thirty locations (points) under cultivation of sugar-cane in the area were selected for snail collection. In the selected localities there existed drains, canals, ditches, and water stands. Preliminary identification of snails was performed at the time of collection. A more complete taxonomical study was made after the samples were transferred to the laboratory of Dezful Health Research station.

Results: The total number of snails collected was 3825 snails, and seven different species were identified: Physa sp . (29%), Gyraulus sp. (19%), Melanoides sp. (16%), Bellamya sp. (14%), Melanopsis sp. (12%), L. gedrosiana, (7%)L. truncatula(2%). No Bulinus truncatus was seen .

Conclusion: Most of these snails are capable of getting involved in the life cycle of some zoonotic helminth parasites, e.g., Fasciolid and Heterophyd. These findings are encouraging. However, in order to avoid any possible undesirable effects on the public's health, constant monitoring, as well as annual malacological surveys, is essential.

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Background and Aim: The most common cancer in Iran is digestive system cancer, the highest incidence of which is reported from the Caspian Sea littoral. This study aimed to determine factors affecting the survival of patients with gastrointestinal cancer using the Cox and parametric models the 2 models were compared.

Materials and Methods: This survey was a prospective study conducted between 1990 and 1991. Data were collected through the Cancer Registry Center in Babol, which functions under supervision of the School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences. We tried to identify cases of gastrointestinal cancers. The individual characteristics of 484 patients, namely, age, sex, family history, marital status, smoking status, occupation, ethnicity, medication status, education, residence (urban, rural), and type of cancer were recorded. The patients were followed up for a period of 15 years, i.e., until 2006 year. To determine the effective factors on survival of patients, the Cox model and parametric models such as exponential, weibull, log-normal, log-logistic, and the AIC criteria and residuals were used to compare the effectiveness of the models. The SAS and STATA software were used for data analysis, with a significant level of 0.05.

Results: Sixty-six percent of the patients (total n=484) were males and 34% females, with a mean age of 59 and 55 years, respectively. Their distribution according to type of cancer was as follows: esophageal cancer, 359 (74.2%) stomach cancer, 110 (22.7%) colorectal cancer, 15(3.1%). Estimated one-, three-, and five-year survival rates were 24%, 16% and 15%, respectively.

Conclusion: The results of this study reveal that gender and family history can be strong risk factors for GI cancer. Log-normal and log-logistic models in multivariate and univariate analyses gave almost similar results. However, based on AIC criteria and residuals analysis, the log-logistic model gives the best fit as compared to other parametric models and can be used instead of the Cox model for determining factors affecting survival of patients with gastrointestinal tract cancer.

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Background and Aim: Many researchers have studied survival (time to death) of gastric cancer patients. Although gastric cancer diagnosed in early stages can be cured by surgery, chance of relapse still exists after operation. Hence, we should consider both events, that is, relapse of the disease and death, in order to be able to make a more precise estimation for survival of the patients. The purpose of this study was to use the competing risks method to estimate the cumulative incidence functions (CIF) of the relapse of disease and death and consequently to estimate the postoperative disease-free survival.
Materials and Methods: A total of 330 patients admitted to Iran Cancer Institute and operated between March 1995 and March 1999 were enrolled in the study. They were followed up for at least 5 years to estimate their 5-year disease-free survival. Information on their demographic, clinical, and therapeutic characteristics, as well as on the type and time of occurrence of the first event (relapse of disease or death) after surgery was collected from their medical records. The direct parametric method was applied to estimate CIFs of relapse of the disease and death, while to adjust the effects of some covariates the parametric regression model was used. Data analysis was done using the R software and a p-value <0.05 was considered statistically significant. The findings were compared with the results obtained on the basis of data analysis in which the competing events were not considered.
Results: The median follow-up time was 37.9 months. Of all the patients 13% experienced relapse and 60.9% death as the first event after surgery. The CIFs of relapse of disease and death 5 years after operation, with due consideration of covariates, were estimated at 11.0% and 68.6%, respectively. Age, stage of disease, and complementary treatment were statistically associated with the CIF of death, while only complementary treatment was related to the CIF of relapse. Older patients and those in more advanced stages of disease were more likely to die after operation. Moreover, while complementary treatment after operation decreased the CIF of relapse of disease, it increased the CIF of death. The disease-free survival of patients 5 years after surgery was 20.(consideringtheeffectsofsomecovariates).
Conclusion: The competing risks method is recommended for analyzing survival data because of its capability in considering different events and, therefore, making it possible to make more precise estimations. By using this method, considering smaller variance estimates for model parameters and also narrow confidence intervals for the cumulative incidence functions of competing events, it is expected to obtain more precise results. Unfortunately, the results have revealed that the disease-free survival of gastric cancer patients is low in Iran.

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Background and Aim: Iran National Polio Laboratory (NPL) is a member of the World Health Organization (WHO) Polio Laboratories Network. NPL receives stool specimens from acute flaccid paralysis (AFP) cases from all the provinces throughout Iran for poliovirus detection and identification. Furthermore, the NPL also detects non-polio enteroviruses (NPEVs) in these specimens.  Recently, NPEVs have come to be believed to be one of the most important causes of AFP following wild poliovirus.  This paper reports the prevalence of different types of NPEVs isolated from the specimens of AFP cases between 1995 and 2000.

Materials and Methods: Stool collection, virus detection and serotype identification were performed according to the WHO standard procedures.

Results: A total of 2180 stool specimens from AFP cases were received at the National Polio Laboratory. Coxsackie B viruse and echoviruses 6, 11, 7 and 13 had the highest frequency, identified in 23.7%, 14.4%, 12.7%, 11% and 10.2% of the NPEVs isolated from AFP cases, respectively. Four cases of echovirus 20 were identified, in 2 cases the patiets having died and in one the patient having been afflicted with residual paralysis. There have been no reports of death or residual paralysis (paralysis continuing after 60 days) due to echoviruse 20.

Conclusion:  Considering the upward trend of AFP cases in Iran, even after wild poliovirus eradication, studies are needed to determine the frequency and type identification of NPEVs and the relationship between NPEVs and residual paralysis in the post-eradication era (2000 onwards).

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  Background and Aim: In many diagnostic studies, including surveying the survival of patients with gastric cancer where each individual after surgery can experience more than one type of event, and the occurrence of one type of event hinders the occurrence of other types of events, the question of competing risk is raised. For checking the effect of each covariate on the occurrence of any event and estimating the hazard function, Cox and Fine and Gray models are used. In the event that the assumptions of two models do not hold, using them will be an incorrect course of action. One way to overcome this problem is to use models that have higher flexibility.

  Materials and Methods: In this study, the demographic, clinical and therapeutic characteristics of 330 patients with gastric cancer who referred from January 1996 to April 2000 to the Cancer Institute of Iran Imam Khomeini Hospital and underwent surgery, including their type, and the time of occurrence of the first event (locoreginal replace/death) for each patient from medical records were collected and evaluated. Using this information, the cumulative hazard function of relapse of disease was plotted by means of three models Cox, Fine and Gray and the flexible one, and was checked against the observed cumulative incidence function of recurrence of disease and, finally, their performance was evaluated.

  Results: Nearly, for each event, the proportionality assumption holds for all the variables . According to the graph of cumulative incidence function for the event of interest (recurrence), it can be seen that the Cox model, has overestimated the cumulative incidence function and the curves of two other models are very similar and also similar to the observed curve. However, the cumulative incidence function of the flexible model is smoother than the others.

  Conclusion: In the competing risk framework, Cox model is not very useful in practice while it seems that the flexible model is not only a good alternative to the Fine and Gray model but will also be superior to it when the assumption of proportionality does not hold.

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  Background and Aim: The objective of this study was to determine factors associated with time to relapse and, thus, retention time, of a cohort of opioid-dependents under methadone maintenance treatment, using survival models, in the Iranian National Center for Addiction Studies (INCAS).

  Materials and Methods: A total of 198 opioid-dependent clients participating in the Methadone Maintenance Treatment Program, implemented by INCAS between April 2007 and March 2011, were included in the study. A Cox proportional hazard (PH) model was applied to determine predictors of relapse time among the patients.

  Results: The data showed that 86 clients relapsed into drug use during the treatment program. The proportional hazard assumption was satisfied according to the goodness of fit test showing that Cox proportional hazard model was appropriate. Estimates of the PH model indicated that an increase of 1mg in the methadone dosage could lead to a decrease of 0.15 in hazard ratio and an increase in the length of treatment (p<0.001). Predictors for raising the probability of drug relapse included suffering from mental disorders (compared to mentally healthy: hazard ratio = 2.29, p<0.001), being a poly-substance user (compared to mono-substance users: hazard ratio = 4.80, p<0.001), and having retention experience in the past (compared to those with no previous therapy: hazard ratio = 1.90, p<0.001). Other variables entered in the model, including social and demographic variables, had no statistically significant effect on hazard ratio.

  Conclusions: Although higher methadone dosages are associated with a longer time to relapse, we recommend highly to pay special attention to providing more therapeutic and consultive services to mental health patients, poly-substance users, and individuals with a past therapy record.

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Background and Aim: Expanded program on immunization is one of the strategic universally accepted methods for control of childhood diseases including poliomyelitis. Oral Polio Vaccine (OPV) which consists of live attenuated poliovirus is considered as appropriate and most convenient tool for nation-wide vaccination. Polio virus is sensitive to heat, so OPV should be kept frozen and transferred to vaccination centers under cold chain conditions. Thermo-stability of vaccine during transportation is very important. Potency test is used to evaluate the quality and stability of vaccine. This is the first documentated study on evaluation of OPV potency kept out of cold chain conditions in Iran. Materials and Methods: To study the effects of time and temperature on potency of polio vaccine, vaccine vials were exposed to 24°C (room temperature) and 37°C (average temperature in tropical regions) for one to seven days. Vaccine potency evaluation was performed according to World Health Organization protocol. Results: It can be inferred from comparison of the results of this study with the international standards that OPV is stable at 37◦C for only one day, but if it is exposed to room temperature for 4-5 days, serotypes 1 and 2 remain unaltered but serotype 3 will lose its potency to a great extent. Conclusions: Although Polio viruses are relatively resistant to environmental conditions, their sensitivity to heat is the reason to transport the vaccine, which contains live attenuated virus, under cold chain conditions. This will prevent the titer of the vaccine virus to decrease. Vaccine stored at temperature below 4°C is preferred, otherwise the vaccine kept at room temperature (24°C) is useable for 4-5 days, and at 37◦C the vaccine is potent only for one day.

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Background and Aim: In many medical studies along with longitudinal data, which are repeatedly measured during a certain time period, survival data are also recorded. In these situations, using models such as, mixed effects models or GEE method for longitudinal data and Cox model for survival data, are not appropriate because some necessary assumptions are not met. Instead, the joint models have been introduced, to consider: 1- measurement error in time-dependent covariates 2-monotone and non-ignorable missing data which occurs after an event and 3- relation between longitudinal and survival outcomes, simultaneously. At this paper, joint model Puts longitudinal response (i.e. creatinine) as a time dependent variable, along with other covariates in survival sub model, to investigate dialysis patients survival. Materials and Methods: This research contained information about 417 patients affected to chronic renal failure, under treatment of continuous ambulatory peritoneal dialysis (CAPD) method. Patients were referred to three medical centers in Tehran (Shariati, Modares and Shafa) between 1997 to 2009.In this study longitudinal data and time dependent covariate were used Therefore, different variables for each person at certain time have been measured. In first some information was gathered from patient’s file, and then effective factors on survival of patients have been determined by using joint model. Results were compared with naive analysis (extended Cox model). For data analyzing, R software and significant level of 0.05 have been used. Results: with using joint model sex, age, diabetes, diastolic blood pressure, haemoglobin, urea, LdL, and creatinine covariates were significant. In extended Cox model, only age and Diastolic blood pressure covariates were considered as effective factors on hazard of death in patients. Conclusion: Joint model assess the effective factors on both endpoints simultaneously. Also it considers missing data that appeared due to an event, and covariates which were measured with error. Therefore in these cases, using joint models that led to better results and more knowledge about dieses, are necessary.

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  Background and Aim : Diagnostic tools for chronic fatigue syndrome, chronic fatigue syndrome questionnaire, created for research and clinical investigations in order to use it as a management tool for monitoring patients with this syndrome. The questionnaire is very comprehensive using a self-reporting system and all internal and external definitions according to the America's Center for Disease Control has been covered. It also assesses current and past activity levels and symptoms of fatigue and malaise after routine daily activities to ensure that these items are evaluated as well. The purpose of this study is to evaluate the reliability and validity of diagnostic questionnaire for Chronic Fatigue Syndrome (CFS).

  Materials and Methods : In the discussion of content validity and reliability of survey studies, chronic fatigue syndrome questionnaire, prepared by the Department of Psychology, DePaul University, and was elected a full copy of the correspondence received from the questionnaire ratings. The questionnaire that was translated content validity was assessed by the 20 members of the faculty. However, re-translated from Persian into English for reference, was prepared with modifications, the validity of its validity was confirmed by the authors. Then, 30 nurses were selected to determine the reliability of the questionnaire chronic fatigue syndrome who was working in a Hospital. Inventory management under center and full justification of the researcher and the participants in the study by researchers at the distribution has been completed. The survey was carried out again after 15 days.

  Results: The instrument showed good reliability and validity. In discussing the content validity of the Persian translation tool by 20 people associated professor of internal review, and its content validity was determined with respect to two of CVI and the results of CVR , and (CVR=0.7 and CVI=0.85) represents CREDIT the content is good . According to the results, the reliability of the questionnaire CFS, Cronbach's alpha to assess the results of the questionnaire showed very good reliability. Two step test reliability coefficients (ICC = Mixed & and Confidence Interval = 95%) also showed a significant relationship among questions as well. However, the internal correlation coefficient obtained for the 8 criteria CFS, showed high internal cohesion.

  Conclusion: This study suggests the CFS questionnaire as a reliable instrument for all levels in research and clinical applications. Using this tool can help with background checks and even in advanced levels to be effective, it has enough power and accuracy in the diagnosis of CFS sufferers.