Survival time and relative risk of death in patients with colorectal cancer in an Iranian population: A cohort study

Background and purpose: Colorectal cancer (CRC) is one of the most prevalent health problems in the world and Iran. This study aimed at determining the survival rate of patients with CRC and the factors influencing it in Iranian patients. Material and Methods: A prospective cohort study was carried out in patients attending 10 state and private hospitals in Tehran during 2006-2011. In this study 1127 patients (totally 2570 individuals-year) were followed up every six months and the follow-up duration was from the definite time of CRC diagnosis until death (or censoring). Only 2 of the patients were censored. Data was analyzed using stata software, bivariate and multivariate analyses, and also Cox regression. Results: The mean age of the patients was 53.5 ± 14 years old at the time of diagnosis. Most of the patients were older than 45 years of age (69.7). The age at diagnosis was significantly different between men and women (P<0.03). The patients were 61.2 male and the rest were female. The rates of mortality in male and female were 96.9 and 83 in 100,000. After the diagnosis has been made 75, 50, and 25 had a survival rate of less than 2.72 years, 5.84 years, and longer than 13 years, respectively. In Cox model some variables including ethnicity, marital status, cancer grade, family history of caner, and smoking were the main determinants of survival. Conclusion: The mean survival time was 5.8 years after diagnosis has been made which shows more improvements compared to previous studies. This study provides some information on CRC survival rate so that action plans could be designed to prevent and control this disease

Spatial and temporal trends of short-term health impacts of PM2.5in Iranian cities; A modelling approach (2013�2016)

Estimation of the spatial and temporal trends of health impacts attributable to air pollution is an effective measure for evaluating implemented interventions. The aim of this study was to estimate the short-term mortality attributable to exposure to PM2.5among individuals older than 30 years old in ten Iranian cities from March 2013 to March 2016 using the World Health Organization�s (WHO) AirQ+ software. Hourly concentrations of PM2.5were acquired from the Department of Environment and Tehran Air Quality Control Company. Only stations with 75 and 50 of valid data were qualified for Tehran and other cities, respectively. The annual average PM2.5concentrations in all ten of the cities were higher than the WHO guideline value of 10 µg m�3The total number of attributable short-term deaths during the three-year period in these 10 cities was 3284 (95 CI: 1207�5244). The average daily premature deaths were calculated to be 3. The highest number of premature deaths within the three-year period was estimated to be 548 in Tehran, largely reflecting its population of nearly 9 million. The western and southern cities of Iran experience severe dust storms and showed a high estimated rate of death attributed to air pollution. The health impacts in all cities decreased in the third year compared to the first year except for Ahvaz, Khoram Abad, and Ilam. Governmental interventions need to be enforced more effectively to reduce the high level of adverse health impacts in Iran. Special considerations should be given to the air quality of cities affected by dust storms. © Taiwan Association for Aerosol Research

A systematic review and meta-analysis of human biomonitoring studies on exposure to environmental pollutants in Iran

Population exposure to environmental contaminants can be precisely observed through human biomonitoring studies. The present study aimed to systematically review all the biomonitoring studies conducted in Iran on some selected carcinogen environmental pollutants. In this systematic review study, 11 carcinogen agents were selected including arsenic, cadmium, chromium, nickel, lindane, benzene, trichloroethylene (TCE), pentachlorophenol (PCP), radon-222, radium-224, � 226, � 228, and tobacco smoke. The Web of Science, PubMed, and Scopus databases were searched for peer-reviewed articles published in English. After several screening steps, data were extracted from the studies. Meta-analyses (a random-effect model using the DerSimonian-Laired method) were performed only for the biomarkers with more than three eligible articles, including cadmium in blood and breast milk, and arsenic in breast milk. Methodological quality of the studies was assessed using the Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies. Of the 610 articles found in the database search, 30 studies were eligible for qualitative review, and 13 were included in the meta-analysis (cadmium in blood (n = 3), cadmium in breast milk (n = 6), and arsenic in breast milk (n = 4)). The overall pooled average concentrations (95 CI) of cadmium in blood, cadmium in breast milk, and arsenic in breast milk were 0.11 (95 CI: 0.08, 0.14), 5.38 (95 CI: 3.60, 6.96), and 1.42 (95 CI: 1.02, 1.81) µg/L, respectively. These values were compared with the biomarker concentrations in other countries and health-based guideline values. This study showed that there is a need for comprehensive action plans to reduce the exposure of general population to these environmental contaminants. © 202

Spatial and temporal trends of short-term health impacts of PM2.5in Iranian cities; A modelling approach (2013�2016)

Estimation of the spatial and temporal trends of health impacts attributable to air pollution is an effective measure for evaluating implemented interventions. The aim of this study was to estimate the short-term mortality attributable to exposure to PM2.5among individuals older than 30 years old in ten Iranian cities from March 2013 to March 2016 using the World Health Organization�s (WHO) AirQ+ software. Hourly concentrations of PM2.5were acquired from the Department of Environment and Tehran Air Quality Control Company. Only stations with 75 and 50 of valid data were qualified for Tehran and other cities, respectively. The annual average PM2.5concentrations in all ten of the cities were higher than the WHO guideline value of 10 µg m�3The total number of attributable short-term deaths during the three-year period in these 10 cities was 3284 (95 CI: 1207�5244). The average daily premature deaths were calculated to be 3. The highest number of premature deaths within the three-year period was estimated to be 548 in Tehran, largely reflecting its population of nearly 9 million. The western and southern cities of Iran experience severe dust storms and showed a high estimated rate of death attributed to air pollution. The health impacts in all cities decreased in the third year compared to the first year except for Ahvaz, Khoram Abad, and Ilam. Governmental interventions need to be enforced more effectively to reduce the high level of adverse health impacts in Iran. Special considerations should be given to the air quality of cities affected by dust storms. © Taiwan Association for Aerosol Research

Burden of mortality attributed to PM2.5 exposure in cities of Iran; contribution of short-term pollution peaks

The objective of this study was to determine the population exposure to PM2.5, and to quantify the effect of eliminating short-term pollution peaks on the number of cause-specific deaths, the number of years of life lost (YLL), and economic losses attributed to exposure to PM2.5 in 25 Iranian cities with available air quality data. Number of deaths and YLL were estimated with AirQ + software tool using available concentration-response functions and life table approach. Furthermore, the value of lost life in each city were calculated using the Value of Statistical Life (VSL) method. Two scenarios were defined; Scenario A, considering actual observed concentrations to estimate the real health effects of PM2.5, and Scenario B, controlling for the effect of air pollution episodes. The results showed that the annual average concentrations of PM2.5 in cities were 1.5�6.1 times higher than the guideline value of WHO (10 μg/m³). The total number of all-cause deaths due to long-term exposure exceeding WHO air quality guideline level was 13321 (95 C.I.: 8837�17378) cases per year in all cities. The total numbers of chronic obstructive pulmonary disease (COPD), lung cancer, ischemic heart disease (IHD), and stroke deaths attributed to the exposure were 274, 315, 1536, and 963 cases, respectively. The total number of YLL over 10 years period in all 25 cities was 486,289 years and the loss of life expectancy ranged from 0.43 to 1.87 years. The sum of economic losses due to lost life exceeded 5.8 billion USD. Except for some cities, avoiding highly polluted days in Scenario B would result in only 5 reduction in overall health or economic effects. These results indicate an urgent need for new comprehensive plans to tackle air pollution in Iranian cities focused on reduction of long term average pollution levels since programs for avoiding highly polluted days lead to a limited health benefits only. © 202

Association of short-term exposure to air pollution with mortality in a middle eastern tourist city

This study investigated the association of short-term exposure to PM10, PM2.5, NO2, O3, and CO with daily all-cause, cardiovascular, ischemic heart disease (IHD), cerebrovascular, and respiratory deaths in Mashhad, a tourist megacity in Iran (2014�2018). A distributed-lag-day, nonlinear model (DLNM) and generalized additive model (GAM) based on the quasi-Poisson distribution were used to explore the exposure-lag-day-response associations. The average (± standard deviation) concentrations of PM10, PM2.5, NO2, O3, and CO were 67.1 (± 35.5), 29.6 (± 14.2), 57.3 (± 24.1), 55.9 (± 16.9), and 1907.6 (± 1362.7) μg/m3, respectively. NO2 was associated with IHD mortality in lag-days 0 to 0�7, and lag-day 1. The relative risks (RRs) for a 10 μg/m3 increase in NO2 ranged from 1.01 (95 CI 0.93, 1.11) at lag-day 0 to 1.04 (95 CI 0.94, 1.16) and 1.03 (95 CI 0.93, 1.14) for lag-day 0�1 (cumulative) and lag-day 1 (non-cumulative), respectively. For all-cause mortality, cumulative exposure to PM2.5 for lag-day 0�7 (1.07, 95 CI 1.00, 1.15) and non-cumulative exposure to NO2 at lag-day 6 (1.02, 95 CI 1.00, 1.03) were significant. Exposure to PM10 (per 10 μg/m3) was significantly associated with respiratory mortality at several lag-days. Adjusting for Ramadan did not significantly affect the results. PM10 had significant associations with respiratory mortality of people ' 65 years old, and men for several lag-days. For IHD, NO2 affected older people, and men and women over different lag-days. Results of multi-pollutant models were similar to the single-pollutant model outcomes. In conclusion, NO2 and PM10 had more significant relationships with adverse health outcomes than the other pollutants. © 2020, Springer Nature B.V

Estimation of the basic reproduction number (R0) of the COVID-19 epidemic in Iran

Background: Estimation of the basic reproduction number of an infectious disease is an important issue for controlling the infection. Here, we aimed to estimate the basic reproduction number (R0) of COVID-19 in Iran. Methods: To estimate R0 in Iran and Tehran, the capital, we used 3 different methods: exponential growth rate, maximum likelihood, and Bayesian time-dependent. Daily number of confirmed cases and serial intervals with a mean of 4.27 days and a standard deviation of 3.44 days with gamma distribution were used. Sensitivity analysis was performed to show the importance of generation time in estimating R0. Results: The epidemic was in its exponential growth 11 days after the beginning of the epidemic (Feb 19, 2020) with doubling time of 1.74 (CI: 1.58-1.93) days in Iran and 1.83 (CI: 1.39-2.71) in Tehran. Nationwide, the value of R0 from February 19 to 29 using exponential growth method, maximum likelihood, and Bayesian time-dependent methods was 4.70 (95 CI: 4.23�5.23), 3.90 (95 CI: 3.47�4.36), and 3.23 (95 CI: 2.94�3.51), respectively. In addition, in Tehran, R0 was 5.14 (95 CI: 4.15�6.37), 4.20 (95 CI: 3.38�5.14), and 3.94 (95 CI: 3.45�4.40) for exponential growth, maximum likelihood, and Bayesian time-dependent methods, respectively. Bayesian time dependent methods usually provide less biased estimates. The results of sensitivity analyses demonstrated that changes in the mean generation time affect estimates of R0. Conclusion: The estimate of R0 for the COVID-19 ranged from 3.94 to 5.14 in Tehran and from 3.23 to 4.70 in nationwide using different methods, which were significantly larger than 1, indicating the potential of COVID-19 to cause an outbreak. This work has been published under CC BY-NC-SA 1.0 license. Copyright © 2020. Iran University of Medical Sciences