Application of discrete event simulation model in analysis on cost-effectiveness of epidemiology screening / 中华流行病学杂志

Discrete event simulation (DES) model is based on individual data, by which discrete events over time are simulated to reflect disease progression. The effects of individual characteristics on disease progression could be considered in the DES model. Moreover, unlike state-transition models, DES model without setting of fixed cycle can contribute to more accurate estimation of event time, especially in the evaluation of the long-term effectiveness of screening strategies for complex diseases in which time dimension needs to be considered. This article introduces the general principles, construction steps, analytic methods and other relevant issues of the DES model. Based on a research case of estimating the cost-effectiveness of screening for abdominal aortic aneurysms in women aged 65 years and above in the United Kingdom, key points in applications of the DES model in analysis on effectiveness of complex disease screening are discussed in detail, including model construction and analysis and interpretation of the results. DES model can predict occurring time of discrete events accurately by establishing the distribution function of their occurring time and is increasingly used to evaluate the screening strategies for complex diseases in which time dimension needs to be considered. In the construction of DES model, it is necessary to pay close attention to the clear presentation of model structure and simulation process and follow the relevant reporting specification to conduct cost-effectiveness analysis to ensure the transparency and repeatability of the research.

Comparison of aspirin treatment strategies for primary prevention of cardiovascular diseases: A decision-analytic Markov modelling study / 北京大学学报(医学版)

OBJECTIVE@#To compare the expected population impact of benefit and risk of aspirin treatment strategies for the primary prevention of cardiovascular diseases recommended by different guidelines in the Chinese Electronic Health Records Research in Yinzhou (CHERRY) study.@*METHODS@#A decision-analytic Markov model was used to simulate and compare different strategies of aspirin treatment, including: Strategy ①: Aspirin treatment for Chinese adults aged 40-69 years with a high 10-year cardiovascular risk, recommended by the 2020 Chinese Guideline on the Primary Prevention of Cardiovascular Diseases; Strategy ②: Aspirin treatment for Chinese adults aged 40-59 years with a high 10-year cardiovascular risk, recommended by the 2022 United States Preventive Services Task Force Recommendation Statement on Aspirin Use to Prevent Cardiovascular Disease; Strategy ③: Aspirin treatment for Chinese adults aged 40-69 years with a high 10-year cardiovascular risk and blood pressure well-controlled (< 150/90 mmHg), recommended by the 2019 Guideline on the Assessment and Management of Cardio-vascular Risk in China. The high 10-year cardiovascular risk was defined as the 10-year predicted risk over 10% based on the 2019 World Health Organization non-laboratory model. The Markov model simulated different strategies for ten years (cycles) with parameters mainly from the CHERRY study or published literature. Quality-adjusted life year (QALY) and the number needed to treat (NNT) for each ischemic event (including myocardial infarction and ischemic stroke) were calculated to assess the effectiveness of the different strategies. The number needed to harm (NNH) for each bleeding event (including hemorrhagic stroke and gastrointestinal bleeding) was calculated to assess the safety. The NNT for each net benefit (i.e., the difference of the number of ischemic events could be prevented and the number of bleeding events would be added) was also calculated. One-way sensitivity analysis on the uncertainty of the incidence rate of cardiovascular diseases and probabilistic sensitivity analysis on the uncertainty of hazard ratios of interventions were conducted.@*RESULTS@#A total of 212 153 Chinese adults, were included in this study. The number of people who were recommended for aspirin treatment Strategies ①-③ was 34 235, 2 813, and 25 111, respectively. The Strategy ③ could gain the most QALY of 403 [95% uncertainty interval (UI): 222-511] years. Compared with Strategy ①, Strategy ③ had similar efficiency but better safety, with the extra NNT of 4 (95%UI: 3-4) and NNH of 39 (95%UI: 19-132). The NNT per net benefit was 131 (95%UI: 102-239) for Strategy ①, 256 (95%UI: 181-737) for Strategy ②, and 132 (95%UI: 104-232) for Strategy ③, making Strategy ③ the most favorable option with a better QALY and safety, along with similar efficiency in terms of net benefit. The results were consistent in the sensitivity analyses.@*CONCLUSION@#The aspirin treatment strategies recommended by the updated guidelines on the primary prevention of cardiovascular diseases showed a net benefit for high-risk Chinese adults from developed areas. However, to balance effectiveness and safety, aspirin is suggested to be used for primary prevention of cardiovascular diseases with consideration for blood pressure control, resulting in better intervention efficiency.

Effectiveness of different screening strategies for type 2 diabete on preventing cardiovascular diseases in a community-based Chinese population using a decision-analytic Markov model / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effectiveness of different screening strategies for type 2 diabetes to prevent cardiovascular disease in a community-based Chinese population from economically developed areas based on the Chinese electronic health records research in Yinzhou (CHERRY) study.@*METHODS@#A Markov model was used to simulate different systematic diabetes screening strategies, including: (1) screening among Chinese adults aged 40-70 years recommended by the 2020 Chinese Guideline for the prevention and Treatment of Type 2 Diabetes (Strategy 1); (2) screening among Chinese adults aged 35 to 70 years recommended by the 2022 American Diabetes Association Standard of Medical Care in Diabetes (Strategy 2); and (3) screening among Chinese adults aged 35-70 years with overweight or obesity recommended by the 2021 United States Preventive Services Task Force Recommendation Statement on Screening for Prediabetes and Type 2 Diabetes (Strategy 3). According to the guidelines, individuals who were screened positively (fasting plasma glucose ≥ 7.0 mmol/L) would be introduced to intensive glycemic targets management (glycated hemoglobin < 7.0%).The Markov model simulated different screening scenarios for ten years (cycles) with parameters mainly from the CHERRY study or published literature. Number of cardiovascular disease events or deaths could be prevented and number needed to screen (NNS) were calculated to compare the effectiveness of the different strategies. One-way sensitivity analysis on the sensitivity of screening methods and probabilistic sensitivity analysis on uncertainties of diabetes incidence, the sensitivity of screening methods, and intensive glycemic management effects were conducted.@*RESULTS@#Totally 289 245 Chinese adults aged 35-70 years without cardiovascular diseases or diagnosed diabetes at baseline were enrolled. In terms of the number of cardiovascular disease events could be prevented, Strategy 1 for systematic diabetes screening among the adults aged 35-70 years was 222 (95%UI: 180-264), Strategy 2 for systematic diabetes screening among the adults aged 40-70 years was 227 (95%UI: 185-271), and Strategy 3 for systematic diabetes screening among the adults aged 35-70 years with obesity or overweight (body mass index ≥ 24 kg/m2) was 131 (95%UI: 98-164), compared with opportunistic screening. NNS per cardiovascular disease event for the strategies 1, 2 and 3 were 1 184 (95%UI: 994-1 456), 1 274 (95%UI: 1 067-1 564) and 814 (95%UI: 649-1 091), respectively. Compared with Strategy 1, NNS per cardiovascular disease event for Strategy 2 increased by 90 (95%UI: -197-381) with similar effectiveness of cardiovascular prevention; however, NNS per cardiovascular disease event for Strategy 3 was reduced by 460 (95%UI: 185-724) in contrast to the Strategy 2, suggesting that the Strategy 3 was more efficient. The results were consistent in multiple sensitivity analyses.@*CONCLUSION@#Systematic screening for diabetes based on the latest guidelines in economically developed areas of China can reduce cardiovascular events and deaths. However, merely lowering the starting age of screening from 40 to 35 years seems ineffective for preventing cardiovascular disease, while screening strategy for Chinese adults aged 35-70 years with overweight or obesity is recommended to improve efficiency.

Effectiveness of statin treatment strategies for primary prevention of cardiovascular diseases in a community-based Chinese population: A decision-analytic Markov model / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effectiveness of statin treatment strategies based on risk assessment for the primary prevention of cardiovascular diseases by the Western guidelines in a community-based Chinese population from economically developed areas using data from the Chinese electronic health records research in Yinzhou (CHERRY) study.@*METHODS@#A Markov model was used to evaluate the effectiveness of the following statin treatment strategies, including: (1) usual care without cardiovascular risk assessment(Strategy 0); (2) using the World Health Organization (WHO) non-laboratory-based risk charts with statin treatment for high-risk group (risk ≥ 20%) (Strategy 1); (3) using the WHO laboratory-based risk charts with statin treatment for high-risk group (risk ≥ 20%) (Strategy 2); and (4) using the Prediction for Atherosclerotic cardiovascular disease Risk in China (China-PAR) model with statin treatment for high-risk group (risk ≥ 10%, Strategy 3). According to the guidelines, adults in the medium-risk group received lifestyle intervention, and adults in the high-risk group received life-style intervention and statin treatment under these strategies. The Markov model simulated different strategies for ten years (cycles) using parameters from the CHERRY study, published data, meta-analyses and systematic reviews for Chinese. The number of cardiovascular events or deaths, as well as the number need to treat (NNT) with statin per cardiovascular event or death prevented, were calculated to compare the effectiveness of different strategies. One-way sensitivity analysis on the uncertainty of incidence rate of cardiovascular diseases, and probabilistic sensitivity analysis on the uncertainty of hazard ratios of interventions were conducted.@*RESULTS@#Totally 225 811 Chinese adults aged 40-79 years without cardiovascular diseases at baseline were enrolled. In contrast to the usual care without risk assessment-based statin treatment strategy, Strategy 1 using the WHO non-laboratory-based risk charts could prevent 3 482 [95% uncertainty interval (UI): 2 110-4 661] cardiovascular events, Strategy 2 using the WHO laboratory-based risk charts could prevent 3 685 (95%UI: 2 255-4 912) events, and Strategy 3 using the China-PAR model could prevent 3 895 (95%UI: 2 396-5 181) events. NNTs with statin per cardiovascular event prevented were 22 (95%UI: 14-54), 21 (95%UI: 14-52), and 27 (95%UI: 17-67), respectively. Strategy 3 could prevent more cardiovascular events, while Strategies 1 and 2 required fewer numbers need to treat with statin per cardiovascular event prevented. The results were consistent in the sensitivity analyses.@*CONCLUSION@#The statin treatment strategies based on risk assessment for the primary prevention of cardiovascular diseases recommended by the Western guidelines could achieve substantive health benefits in adults from developed areas of China. Using the China-PAR model for cardiovascular risk assessment could prevent more cardiovascular diseases while using the WHO risk charts seems more efficient.

An overview of the removal of algal toxins by water treatment process / 军事医学

The environmental and health problems caused by the frequent occurrence of cyanobacteria blooming and its secondary metabolites,algal toxins, have become a hot spot in environmental science research.This article reviews the production and contamination status of algal toxins, and the removal effects of microcystins(MCs), anatoxin-a(ANTX) and other algal toxins by different water treatment processes, including coagulation and sedimentation, ozone oxidation, activated carbon adsorption,membrane treatment, chlorination and UV irradiation.Furthermore, the factors affecting the removal effect are analyzed,and the advantages and limitations of each water treatment process are summarized.Finally, some feasible proposals are presented regarding the future research of removing algal toxins.