| BackgroundTuberculosis (TB) and diabetes mellitus (DM) are major public health challenge in China. In2009, the national sampling survey results show that DM prevalence has been reached to9.7%, and will keep rising in future. According to WHO2013global TB control report, the burden of TB in China takes the second part in the world, and the number of Multi Drug Resistant TB (MDR-TB) patients comes to the first. In2012, the number of patients with TB is90,000in China. Both of the two diseases have been caused heavy economic burden to patients, families, and society. A series of studies from different countries have confirmed that people with DM are at high risk of TB. More seriously, patients with comorbidity of DM and TB lead to the difficulty of treatment, extended sputum culture turn, increased treatment failure, drug resistant rate and mortality rate.In China, the most effective in TB control strategy is case finding. Early finding of TB cases will lead to the early treatment and better outcome of TB, reducing the economic burden of TB, controlling the spread of TB, and moving forward the control gate of TB. Delivering TB case finding among people with risk of TB will diagnose more cases, and achieve better effect. Therefore, based on huge DM population in China and the connection between the two diseases, conducting TB case finding in patients with DM is significant meaningful and important for TB control.In China, TB cases finding in patients with DM include passive case finding and active case finding. Passive case finding is patient oriented, patients with suspected TB seek for service t in TB prevention and control institutions due to their symptoms. Active case finding is project or institutions oriented, it strengthen TB case detection in particular patients. In China, active case finding includes community-based active case finding and clinic-based active case finding. Community-based active case finding is conducted by health institutions through covering the community patients with DM to maximum TB case detection. Clinic-based active case finding is hold by health provider from clinic of endocrinology in the hospital for examination of DM in TB case finding. Active case finding is effective for early finding for TB cases. From the point of government policy-making, it is essential to focus on how to evaluate the economic effect of cases finding in patients with DM using appropriate quantitative methods. Due to the recent researches, study of TB case finding in patients with DM is limited, and lack of evidence on economics evaluation of TB case finding in patients with DM. Previous studies focus on economics evaluation of TB case finding tool.The domestic and foreign researches have shown that decision-tree model is intuitionistic, multivariate and quantized, which is used for optimization of TB controlling strategies and is easy to be understood and accepted assisted with relevant health economics indicators. Markov model can evaluate the effectiveness of life years (LY) and quality adjusted life years (QALYs) of the research objects under different controlling strategies through simulating the complex process of disease chronic evolution. As TB is a chronic infectious disease, decision tree-Markov model can combine the merits of two models and apply in the evaluation research of TB ultimate effectiveness. Although applying decision tree-Markov model for economic evaluation in TB controlling area is common in foreign researches, decision-tree model is applied more often in domestic researches while the combination of decision tree-Markov model is lack of application.This research carries out effectiveness evaluation and economic evaluation by building decision tree-Markov model for TB case finding strategies among patients with DM in China and optimizes the existing case finding strategies in order to provide evidence for health decision makers to formulate TB controlling strategies.ObjectivesGeneral objective:To build decision tree-Markov model for the existing main case finding strategies and carry out effectiveness evaluation and economic evaluation for existing case finding strategies quantitatively to provide evidence-based evidence for China’s TB controlling strategies. This is based on data of three parts:the comprehensive analysis of the characters of China’s existing main TB case finding strategies in patients with DM, the program survey data for community-based active case finding and clinic-based active case finding, the regular data and literature data analysis of passive case finding in China.Specific objectives:(1) To analyze the characters of China’s existing main TB case finding strategies in patients with DM and the survey results of program.(2) To provide important parameters through program survey data and literature data, and build decision tree-Markov model for TB case finding strategies in patients with DM in China.(3) To carry out effectiveness evaluation and economic evaluation for the existing main case finding strategies and optimize the case finding strategies using the decision tree-Markov model in order to provide scientific evidence for health decision making.Methods(1) Economic Evaluation Methods. The economic evaluation of this research is based on social perspective, which is most common and most rational. Cost analysis is based on social perspective and the total expected cost produced by different case finding strategies includes screening cost and infection cost. Screening cost is cost of active programs of different case finding strategies, and what we measured in this research is direct cost including direct health service cost and direct non-health service cost. Infection cost is social economic burden caused by TB infection. The result indicators selected in this research include effectiveness and utility. Effectiveness includes intermediate effectiveness and ultimate effectiveness. TB cases found and TB cases prevented are the intermediate effectiveness indicators. Ultimate effectiveness indicators include TB cases averted, TB morbidity reduced, Death averted, Mortality reduced and life year saved. Utility indicator is quality adjusted life years (QALYs). This research discounts the health results using the same rate as cost. This research builds decision-tree models of different case finding strategies for intermediate effectiveness and decision tree-Markov models for ultimate effectiveness. Then simulate the expected cost and expected results in a cohort of patients with DM after20years TB incubation period under different case finding strategies. After that, apply cost-effectiveness analysis and cost-utility analysis to carry out the economic evaluation. Finally, analyze the uncertainty of this research, which is called sensitivity analysis. It analyzes the influence of change of important parameters on cost-effectiveness ratio and cost-utility ratio of different case finding strategies.(2) Data source and methods. The passive TB case finding for patients with DM in China is the routine work of TB case finding. Community-based active case finding relies on the program of Operational Research in Intensified Case Finding for Active TB in a High-Risk Population with DM, which is funded by Office of WHO Western Pacific Region TB control program. The research group carried out the TB case finding research from May to July,2012in two sample areas of Shandong Province, China.4,085patients with DM were included and14TB cases were newly found. Clinic-based active case finding relies on the program of Perspective Research of TB case finding in patients with DM in China funded by World DM Foundation, which was carried out in5cities in China. The5cities were selected according to the economic developing level and geographical location. The field investigation was carried out in one hospital of every city, which detects TB cases in patients with DM who seek for service in endocrinology clinics. The field investigation was carried out from September2011to May2012and11,330outpatient patients with DM were included, among which48TB cases were newly found.The cost parameters in the decision-tree models and decision tree-Markov models built include screening cost and infection cost parameters. Screening cost parameters mainly came from field investigation of the program while some of them came from the literature analysis. Infection cost parameters mainly referred to the literature analysis data and experts consultation results. Screening procedure parameters include participation rate of patients with DM and TB case finding rate in patients with DM. Screening procedure parameters are the core parameters in the models. Screening procedure parameters in community-based and clinic-based active case finding strategies came from field investigation results while the parameters in passive case finding strategies came from the national level data published by WHO. Markov model simulates the complex process of disease chronic evolution, which is the interconverting process among different disease statuses of TB. TB infection parameters are the interconverting probabilities among different disease statuses of TB, which mainly come from WHO reports, TB morbidity predicting models in China, relevant literature data and experts consultation results.Main ResultsCost analysis:It includes the analysis of screening cost and infection cost of different case finding strategies.The total screening cost of community-based active case finding strategy is￥57,970,4,085patients with DM were screened. The screening cost of community-based active case finding strategy is￥14.19per case. The total screening cost of clinic-based active case finding strategy is￥129,704,11,330patients with DM were screened. The screening cost of clinic-based active case finding strategy is￥11.45per case. The infection cost of non-drug resistant TB is￥2,908.32, the infection cost of MDR-TB infection cost is￥5,561.67. A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model, the expected cost of community-based active case finding strategy is￥2,729,141.79; the expected cost of clinic-based active case finding strategy is￥2,397,796.63.(2) Effectiveness and utility analysis.Intermediate effectiveness analysis:1) TB cases found:According to the research findings of the project, there were14TB cases under the community-based active case finding strategy and48TB cases were found in the clinic-based active case finding strategy. To analysis the effect of different case finding in societal perspective, the participation rate was considered and was put into the decision tree model. A cohort of10,000patients with DM was simulated in the decision tree model. The results showed that26TB cases can be found under community-based active case finding strategy,13TB patients can be found under clinic-based active case finding strategy and7TB patients can be found under passive case finding strategy.2) TB cases prevented.19TB cases can be prevented under community-based active case finding strategy,6TB patients can be prevented under clinic-based active case finding strategy.Ultimate effectiveness analysis:1) TB cases averted. A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model,31TB cases can be averted under community-based active case finding strategy,10TB cases can be averted under clinic-based active case finding strategy.2) TB morbidity reduced. A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model, community-based active case finding strategy could reduce26.2/100,000TB morbidity, clinic-based active case finding strategy could reduce8.5/100,000TB morbidity.3) Deaths averted. A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model,83deaths can be averted under community-based active case finding strategy,30deaths can be averted under clinic-based active case finding strategy.4) Mortality reduced. A cohort of 10,000patients with DM was simulated for20years in the decision tree-Markov model, community-based active case finding strategy could reduce0.7‰TB mortality, clinic-based active case finding strategy could reduce0.2‰TB mortality.5) Life year saved. A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model,167life years can be saved under community-based active case finding strategy,65life years can be saved under clinic-based active case finding strategy.Utility analysis:Quality adjusted life years (QALYs). A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model,152QALYs can be gained additionally under community-based active case finding strategy,61QALYs can be gained additionally under clinic-based active case finding strategy.(3) Cost-effectiveness and cost-utility analysis:The cost of finding a TB case under community-based active case finding strategy was￥3,749.53, cost of finding a TB case under clinic-based active case finding strategy is■1,770.35, incremental analysis showed that￥5,728.52was needed to be paid when finding an additional TB case under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. The cost of preventing a TB case under community-based active case finding strategy was￥5,130.80, cost of preventing a TB case under clinic-based active case finding strategy is￥3,856.76, incremental analysis showed that￥5,728.52was needed to be paid when preventing an additional TB case under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group.A cohort of10,000patients with DM was simulated for20years in the decision tree-Markov model. The cost of averting a TB case under community-based active case finding strategy was￥88,036.83, cost of averting a TB case under clinic-based active case finding strategy is￥239,779.66, incremental analysis showed that￥15,783.34was needed to be paid when averting an additional TB case under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. The cost of reducing1/100,000TB morbidity under community-based active case finding strategy was￥104,165.72, cost of reducing1/100,000TB morbidity under clinic-based active case finding strategy is￥282,093.72, incremental analysis showed that￥18,720.07was needed to be paid when reducing additional1/100,000TB morbidity under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. The cost of averting a death case under community-based active case finding strategy was￥32,881.23, cost of averting a TB death under clinic-based active case finding strategy is￥79,926.55, incremental analysis showed that￥6,251.80was needed to be paid when averting an additional TB death under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. The cost of reducing1‰mortality under community-based active case finding strategy was￥3,898,773.99, cost of reducing1‰mortality under clinic-based active case finding strategy is￥11,988,983.15, incremental analysis showed that￥157,783.41was needed to be paid when reducing additional1‰mortality under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. The cost of saving one life year under community-based active case finding strategy was￥16,342.17, cost of saving one life year under clinic-based active case finding strategy is￥36,889.18, incremental analysis showed that￥3,248.48was needed to be paid when additionally saving one life year under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group.The cost of additionally gaining one QALY under community-based active case finding strategy was￥17,954.88, cost of additionally gaining one QALY under clinic-based active case finding strategy is￥38,060.26, incremental analysis showed that￥3,722.97was needed to be paid when having one additional QALY under community-based active case finding strategy when using clinic-based active case finding strategy as the reference group. Conclusions and Policy ImplicationsConclusions:(1) The research found that, as for the intermediate effectiveness and ultimate effectiveness, community-based active case finding strategy is better than clinic-based case finding strategy;(2) As for intermediate effectiveness, clinic-based active case finding strategy is more cost-effective; as for ultimate effectiveness and utility(QALYs), community-based active case finding strategy is more cost-effective;(3) As for all effectiveness indicators except for mortality reduced, the incremental analysis showed that community-based active case finding strategy is consistent with the principles of economics when using China’s per capita gross domestic product (￥38,459.47) in2012as a third party payment standard (ICER<per capita gross domestic product).Patients with DM is a high-risk population of developing TB, collaborative management and control of DM and TB would have far-reaching significance in China. And according to the conclusion of the research, there would be suitable strategies for strengthening the management of the two diseases. Combined with effectiveness analysis and cost-effectiveness analysis, community-based active case finding strategy may be the best way when considering the external effects of TB. The core of using existing tools to strengthen the management and control of DM and TB disease is to establish collaborative management mechanisms to find the two diseases early, specific strategies include:(1) Strengthening the improvement of the community health records and the community-level management of patients with DM, which will help to effectively control DM and TB;(2) At the same time, it is recommended that management of patients with TB bringing into basic public health services. The result of the economic evaluation suggests the community-based active case finding strategy may be the best way;(3) Strengthening community functions and duties of community physicians and general hospital specialist, taking measures such as carrying regular census in vulnerable populations to find TB cases early and constructing the mechanism of standard screening programs;(4) In the course of monitoring DM and TB, clinic-based active case finding strategy could be a supplement ways of routine monitoring programs to enhance early detection of TB. |
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